Active Record objects don‘t specify their attributes directly, but rather infer them from the table definition with which they‘re linked. Adding, removing, and changing attributes and their type is done directly in the database. Any change is instantly reflected in the Active Record objects. The mapping that binds a given Active Record class to a certain database table will happen automatically in most common cases, but can be overwritten for the uncommon ones.
See the mapping rules in table_name and the full example in files/README.html for more insight.
Active Records accept constructor parameters either in a hash or as a block. The hash method is especially useful when you‘re receiving the data from somewhere else, like an HTTP request. It works like this:
user = User.new(:name => "David", :occupation => "Code Artist") user.name # => "David"
You can also use block initialization:
user = User.new do |u| u.name = "David" u.occupation = "Code Artist" end
And of course you can just create a bare object and specify the attributes after the fact:
user = User.new user.name = "David" user.occupation = "Code Artist"
Conditions can either be specified as a string, array, or hash representing the WHERE-part of an SQL statement. The array form is to be used when the condition input is tainted and requires sanitization. The string form can be used for statements that don‘t involve tainted data. The hash form works much like the array form, except only equality and range is possible. Examples:
class User < ActiveRecord::Base def self.authenticate_unsafely(user_name, password) find(:first, :conditions => "user_name = '#{user_name}' AND password = '#{password}'") end def self.authenticate_safely(user_name, password) find(:first, :conditions => [ "user_name = ? AND password = ?", user_name, password ]) end def self.authenticate_safely_simply(user_name, password) find(:first, :conditions => { :user_name => user_name, :password => password }) end end
The authenticate_unsafely method inserts the parameters directly into the query and is thus susceptible to SQL-injection attacks if the user_name and password parameters come directly from an HTTP request. The authenticate_safely and authenticate_safely_simply both will sanitize the user_name and password before inserting them in the query, which will ensure that an attacker can‘t escape the query and fake the login (or worse).
When using multiple parameters in the conditions, it can easily become hard to read exactly what the fourth or fifth question mark is supposed to represent. In those cases, you can resort to named bind variables instead. That‘s done by replacing the question marks with symbols and supplying a hash with values for the matching symbol keys:
Company.find(:first, :conditions => [ "id = :id AND name = :name AND division = :division AND created_at > :accounting_date", { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' } ])
Similarly, a simple hash without a statement will generate conditions based on equality with the SQL AND operator. For instance:
Student.find(:all, :conditions => { :first_name => "Harvey", :status => 1 }) Student.find(:all, :conditions => params[:student])
A range may be used in the hash to use the SQL BETWEEN operator:
Student.find(:all, :conditions => { :grade => 9..12 })
An array may be used in the hash to use the SQL IN operator:
Student.find(:all, :conditions => { :grade => [9,11,12] })
All column values are automatically available through basic accessors on the Active Record object, but sometimes you want to specialize this behavior. This can be done by overwriting the default accessors (using the same name as the attribute) and calling read_attribute(attr_name) and write_attribute(attr_name, value) to actually change things. Example:
class Song < ActiveRecord::Base # Uses an integer of seconds to hold the length of the song def length=(minutes) write_attribute(:length, minutes.to_i * 60) end def length read_attribute(:length) / 60 end end
You can alternatively use self[:attribute]=(value) and self[:attribute] instead of write_attribute(:attribute, value) and read_attribute(:attribute) as a shorter form.
In addition to the basic accessors, query methods are also automatically available on the Active Record object. Query methods allow you to test whether an attribute value is present.
For example, an Active Record User with the name attribute has a name? method that you can call to determine whether the user has a name:
user = User.new(:name => "David") user.name? # => true anonymous = User.new(:name => "") anonymous.name? # => false
Sometimes you want to be able to read the raw attribute data without having the column-determined typecast run its course first. That can be done by using the <attribute>_before_type_cast accessors that all attributes have. For example, if your Account model has a balance attribute, you can call account.balance_before_type_cast or account.id_before_type_cast.
This is especially useful in validation situations where the user might supply a string for an integer field and you want to display the original string back in an error message. Accessing the attribute normally would typecast the string to 0, which isn‘t what you want.
Dynamic attribute-based finders are a cleaner way of getting (and/or creating) objects by simple queries without turning to SQL. They work by appending the name of an attribute to find_by_, find_last_by_, or find_all_by_, so you get finders like Person.find_by_user_name, Person.find_all_by_last_name, and Payment.find_by_transaction_id. So instead of writing Person.find(:first, :conditions => ["user_name = ?", user_name]), you just do Person.find_by_user_name(user_name). And instead of writing Person.find(:all, :conditions => ["last_name = ?", last_name]), you just do Person.find_all_by_last_name(last_name).
It‘s also possible to use multiple attributes in the same find by separating them with "and", so you get finders like Person.find_by_user_name_and_password or even Payment.find_by_purchaser_and_state_and_country. So instead of writing Person.find(:first, :conditions => ["user_name = ? AND password = ?", user_name, password]), you just do Person.find_by_user_name_and_password(user_name, password).
It‘s even possible to use all the additional parameters to find. For example, the full interface for Payment.find_all_by_amount is actually Payment.find_all_by_amount(amount, options). And the full interface to Person.find_by_user_name is actually Person.find_by_user_name(user_name, options). So you could call Payment.find_all_by_amount(50, :order => "created_on"). Also you may call Payment.find_last_by_amount(amount, options) returning the last record matching that amount and options.
The same dynamic finder style can be used to create the object if it doesn‘t already exist. This dynamic finder is called with find_or_create_by_ and will return the object if it already exists and otherwise creates it, then returns it. Protected attributes won‘t be set unless they are given in a block. For example:
# No 'Summer' tag exists Tag.find_or_create_by_name("Summer") # equal to Tag.create(:name => "Summer") # Now the 'Summer' tag does exist Tag.find_or_create_by_name("Summer") # equal to Tag.find_by_name("Summer") # Now 'Bob' exist and is an 'admin' User.find_or_create_by_name('Bob', :age => 40) { |u| u.admin = true }
Use the find_or_initialize_by_ finder if you want to return a new record without saving it first. Protected attributes won‘t be set unless they are given in a block. For example:
# No 'Winter' tag exists winter = Tag.find_or_initialize_by_name("Winter") winter.new_record? # true
To find by a subset of the attributes to be used for instantiating a new object, pass a hash instead of a list of parameters. For example:
Tag.find_or_create_by_name(:name => "rails", :creator => current_user)
That will either find an existing tag named "rails", or create a new one while setting the user that created it.
Active Record can serialize any object in text columns using YAML. To do so, you must specify this with a call to the class method serialize. This makes it possible to store arrays, hashes, and other non-mappable objects without doing any additional work. Example:
class User < ActiveRecord::Base serialize :preferences end user = User.create(:preferences => { "background" => "black", "display" => large }) User.find(user.id).preferences # => { "background" => "black", "display" => large }
You can also specify a class option as the second parameter that‘ll raise an exception if a serialized object is retrieved as a descendant of a class not in the hierarchy. Example:
class User < ActiveRecord::Base serialize :preferences, Hash end user = User.create(:preferences => %w( one two three )) User.find(user.id).preferences # raises SerializationTypeMismatch
Active Record allows inheritance by storing the name of the class in a column that by default is named "type" (can be changed by overwriting Base.inheritance_column). This means that an inheritance looking like this:
class Company < ActiveRecord::Base; end class Firm < Company; end class Client < Company; end class PriorityClient < Client; end
When you do Firm.create(:name => "37signals"), this record will be saved in the companies table with type = "Firm". You can then fetch this row again using Company.find(:first, "name = ‘37signals’") and it will return a Firm object.
If you don‘t have a type column defined in your table, single-table inheritance won‘t be triggered. In that case, it‘ll work just like normal subclasses with no special magic for differentiating between them or reloading the right type with find.
Note, all the attributes for all the cases are kept in the same table. Read more: www.martinfowler.com/eaaCatalog/singleTableInheritance.html
Connections are usually created through ActiveRecord::Base.establish_connection and retrieved by ActiveRecord::Base.connection. All classes inheriting from ActiveRecord::Base will use this connection. But you can also set a class-specific connection. For example, if Course is an ActiveRecord::Base, but resides in a different database, you can just say Course.establish_connection and Course and all of its subclasses will use this connection instead.
This feature is implemented by keeping a connection pool in ActiveRecord::Base that is a Hash indexed by the class. If a connection is requested, the retrieve_connection method will go up the class-hierarchy until a connection is found in the connection pool.
Note: The attributes listed are class-level attributes (accessible from both the class and instance level). So it‘s possible to assign a logger to the class through Base.logger= which will then be used by all instances in the current object space.
VALID_FIND_OPTIONS | = | [ :conditions, :include, :joins, :limit, :offset, :order, :select, :readonly, :group, :having, :from, :lock ] |
set_table_name | -> | table_name= |
set_primary_key | -> | primary_key= |
set_inheritance_column | -> | inheritance_column= |
set_sequence_name | -> | sequence_name= |
sanitize_sql_for_conditions | -> | sanitize_sql |
sanitize_sql_hash_for_conditions | -> | sanitize_sql_hash |
sanitize_sql | -> | sanitize_conditions |
abstract_class | [RW] | Set this to true if this is an abstract class (see abstract_class?). |
Overwrite the default class equality method to provide support for association proxies.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1454 1454: def ===(object) 1455: object.is_a?(self) 1456: end
Returns whether this class is a base AR class. If A is a base class and B descends from A, then B.base_class will return B.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1470 1470: def abstract_class? 1471: defined?(@abstract_class) && @abstract_class == true 1472: end
Deprecated and no longer has any effect.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 92 92: def allow_concurrency 93: ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency has been deprecated and no longer has any effect. Please remove all references to allow_concurrency.") 94: end
Deprecated and no longer has any effect.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 97 97: def allow_concurrency=(flag) 98: ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency= has been deprecated and no longer has any effect. Please remove all references to allow_concurrency=.") 99: end
Specifies a white list of model attributes that can be set via mass-assignment, such as new(attributes), update_attributes(attributes), or attributes=(attributes)
This is the opposite of the attr_protected macro: Mass-assignment will only set attributes in this list, to assign to the rest of attributes you can use direct writer methods. This is meant to protect sensitive attributes from being overwritten by malicious users tampering with URLs or forms. If you‘d rather start from an all-open default and restrict attributes as needed, have a look at attr_protected.
class Customer < ActiveRecord::Base attr_accessible :name, :nickname end customer = Customer.new(:name => "David", :nickname => "Dave", :credit_rating => "Excellent") customer.credit_rating # => nil customer.attributes = { :name => "Jolly fellow", :credit_rating => "Superb" } customer.credit_rating # => nil customer.credit_rating = "Average" customer.credit_rating # => "Average"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1057 1057: def attr_accessible(*attributes) 1058: write_inheritable_attribute(:attr_accessible, Set.new(attributes.map(&:to_s)) + (accessible_attributes || [])) 1059: end
Attributes named in this macro are protected from mass-assignment, such as new(attributes), update_attributes(attributes), or attributes=(attributes).
Mass-assignment to these attributes will simply be ignored, to assign to them you can use direct writer methods. This is meant to protect sensitive attributes from being overwritten by malicious users tampering with URLs or forms.
class Customer < ActiveRecord::Base attr_protected :credit_rating end customer = Customer.new("name" => David, "credit_rating" => "Excellent") customer.credit_rating # => nil customer.attributes = { "description" => "Jolly fellow", "credit_rating" => "Superb" } customer.credit_rating # => nil customer.credit_rating = "Average" customer.credit_rating # => "Average"
To start from an all-closed default and enable attributes as needed, have a look at attr_accessible.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1024 1024: def attr_protected(*attributes) 1025: write_inheritable_attribute(:attr_protected, Set.new(attributes.map(&:to_s)) + (protected_attributes || [])) 1026: end
Attributes listed as readonly can be set for a new record, but will be ignored in database updates afterwards.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1067 1067: def attr_readonly(*attributes) 1068: write_inheritable_attribute(:attr_readonly, Set.new(attributes.map(&:to_s)) + (readonly_attributes || [])) 1069: end
Returns the base AR subclass that this class descends from. If A extends AR::Base, A.base_class will return A. If B descends from A through some arbitrarily deep hierarchy, B.base_class will return A.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1461 1461: def base_class 1462: class_of_active_record_descendant(self) 1463: end
Log and benchmark multiple statements in a single block. Example:
Project.benchmark("Creating project") do project = Project.create("name" => "stuff") project.create_manager("name" => "David") project.milestones << Milestone.find(:all) end
The benchmark is only recorded if the current level of the logger is less than or equal to the log_level, which makes it easy to include benchmarking statements in production software that will remain inexpensive because the benchmark will only be conducted if the log level is low enough.
The logging of the multiple statements is turned off unless use_silence is set to false.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1434 1434: def benchmark(title, log_level = Logger::DEBUG, use_silence = true) 1435: if logger && logger.level <= log_level 1436: result = nil 1437: ms = Benchmark.ms { result = use_silence ? silence { yield } : yield } 1438: logger.add(log_level, '%s (%.1fms)' % [title, ms]) 1439: result 1440: else 1441: yield 1442: end 1443: end
Returns an array of column names as strings.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1283 1283: def column_names 1284: @column_names ||= columns.map { |column| column.name } 1285: end
Returns an array of column objects for the table associated with this class.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1269 1269: def columns 1270: unless defined?(@columns) && @columns 1271: @columns = connection.columns(table_name, "#{name} Columns") 1272: @columns.each { |column| column.primary = column.name == primary_key } 1273: end 1274: @columns 1275: end
Returns true if ActiveRecord is connected.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 127 127: def connected? 128: connection_handler.connected?(self) 129: end
Returns the connection currently associated with the class. This can also be used to "borrow" the connection to do database work unrelated to any of the specific Active Records.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 114 114: def connection 115: retrieve_connection 116: end
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 118 118: def connection_pool 119: connection_handler.retrieve_connection_pool(self) 120: end
Returns an array of column objects where the primary id, all columns ending in "_id" or "_count", and columns used for single table inheritance have been removed.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1289 1289: def content_columns 1290: @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column } 1291: end
Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part. The use of this method should be restricted to complicated SQL queries that can‘t be executed using the ActiveRecord::Calculations class methods. Look into those before using this.
Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 914 914: def count_by_sql(sql) 915: sql = sanitize_conditions(sql) 916: connection.select_value(sql, "#{name} Count").to_i 917: end
Creates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.
The attributes parameter can be either be a Hash or an Array of Hashes. These Hashes describe the attributes on the objects that are to be created.
# Create a single new object User.create(:first_name => 'Jamie') # Create an Array of new objects User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) # Create a single object and pass it into a block to set other attributes. User.create(:first_name => 'Jamie') do |u| u.is_admin = false end # Creating an Array of new objects using a block, where the block is executed for each object: User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) do |u| u.is_admin = false end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 717 717: def create(attributes = nil, &block) 718: if attributes.is_a?(Array) 719: attributes.collect { |attr| create(attr, &block) } 720: else 721: object = new(attributes) 722: yield(object) if block_given? 723: object.save 724: object 725: end 726: end
Decrement a number field by one, usually representing a count.
This works the same as increment_counter but reduces the column value by 1 instead of increasing it.
# Decrement the post_count column for the record with an id of 5 DiscussionBoard.decrement_counter(:post_count, 5)
# File vendor/rails/activerecord/lib/active_record/base.rb, line 996 996: def decrement_counter(counter_name, id) 997: update_counters(id, counter_name => -1) 998: end
Deletes the row with a primary key matching the id argument, using a SQL DELETE statement, and returns the number of rows deleted. Active Record objects are not instantiated, so the object‘s callbacks are not executed, including any :dependent association options or Observer methods.
You can delete multiple rows at once by passing an Array of ids.
Note: Although it is often much faster than the alternative, destroy, skipping callbacks might bypass business logic in your application that ensures referential integrity or performs other essential jobs.
# Delete a single row Todo.delete(1) # Delete multiple rows Todo.delete([2,3,4])
# File vendor/rails/activerecord/lib/active_record/base.rb, line 775 775: def delete(id) 776: delete_all([ "#{connection.quote_column_name(primary_key)} IN (?)", id ]) 777: end
Deletes the records matching conditions without instantiating the records first, and hence not calling the destroy method nor invoking callbacks. This is a single SQL DELETE statement that goes straight to the database, much more efficient than destroy_all. Be careful with relations though, in particular :dependent rules defined on associations are not honored. Returns the number of rows affected.
Post.delete_all("person_id = 5 AND (category = 'Something' OR category = 'Else')") Post.delete_all(["person_id = ? AND (category = ? OR category = ?)", 5, 'Something', 'Else'])
Both calls delete the affected posts all at once with a single DELETE statement. If you need to destroy dependent associations or call your before_* or after_destroy callbacks, use the destroy_all method instead.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 897 897: def delete_all(conditions = nil) 898: sql = "DELETE FROM #{quoted_table_name} " 899: add_conditions!(sql, conditions, scope(:find)) 900: connection.delete(sql, "#{name} Delete all") 901: end
True if this isn‘t a concrete subclass needing a STI type condition.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1385 1385: def descends_from_active_record? 1386: if superclass.abstract_class? 1387: superclass.descends_from_active_record? 1388: else 1389: superclass == Base || !columns_hash.include?(inheritance_column) 1390: end 1391: end
Destroy an object (or multiple objects) that has the given id, the object is instantiated first, therefore all callbacks and filters are fired off before the object is deleted. This method is less efficient than ActiveRecord#delete but allows cleanup methods and other actions to be run.
This essentially finds the object (or multiple objects) with the given id, creates a new object from the attributes, and then calls destroy on it.
# Destroy a single object Todo.destroy(1) # Destroy multiple objects todos = [1,2,3] Todo.destroy(todos)
# File vendor/rails/activerecord/lib/active_record/base.rb, line 798 798: def destroy(id) 799: if id.is_a?(Array) 800: id.map { |one_id| destroy(one_id) } 801: else 802: find(id).destroy 803: end 804: end
Destroys the records matching conditions by instantiating each record and calling its destroy method. Each object‘s callbacks are executed (including :dependent association options and before_destroy/after_destroy Observer methods). Returns the collection of objects that were destroyed; each will be frozen, to reflect that no changes should be made (since they can‘t be persisted).
Note: Instantiation, callback execution, and deletion of each record can be time consuming when you‘re removing many records at once. It generates at least one SQL DELETE query per record (or possibly more, to enforce your callbacks). If you want to delete many rows quickly, without concern for their associations or callbacks, use delete_all instead.
Person.destroy_all("last_login < '2004-04-04'") Person.destroy_all(:status => "inactive")
# File vendor/rails/activerecord/lib/active_record/base.rb, line 876 876: def destroy_all(conditions = nil) 877: find(:all, :conditions => conditions).each { |object| object.destroy } 878: end
Establishes the connection to the database. Accepts a hash as input where the :adapter key must be specified with the name of a database adapter (in lower-case) example for regular databases (MySQL, Postgresql, etc):
ActiveRecord::Base.establish_connection( :adapter => "mysql", :host => "localhost", :username => "myuser", :password => "mypass", :database => "somedatabase" )
Example for SQLite database:
ActiveRecord::Base.establish_connection( :adapter => "sqlite", :database => "path/to/dbfile" )
Also accepts keys as strings (for parsing from YAML for example):
ActiveRecord::Base.establish_connection( "adapter" => "sqlite", "database" => "path/to/dbfile" )
The exceptions AdapterNotSpecified, AdapterNotFound and ArgumentError may be returned on an error.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 51 51: def self.establish_connection(spec = nil) 52: case spec 53: when nil 54: raise AdapterNotSpecified unless defined? RAILS_ENV 55: establish_connection(RAILS_ENV) 56: when ConnectionSpecification 57: @@connection_handler.establish_connection(name, spec) 58: when Symbol, String 59: if configuration = configurations[spec.to_s] 60: establish_connection(configuration) 61: else 62: raise AdapterNotSpecified, "#{spec} database is not configured" 63: end 64: else 65: spec = spec.symbolize_keys 66: unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end 67: 68: begin 69: require 'rubygems' 70: gem "activerecord-#{spec[:adapter]}-adapter" 71: require "active_record/connection_adapters/#{spec[:adapter]}_adapter" 72: rescue LoadError 73: begin 74: require "active_record/connection_adapters/#{spec[:adapter]}_adapter" 75: rescue LoadError 76: raise "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{$!})" 77: end 78: end 79: 80: adapter_method = "#{spec[:adapter]}_connection" 81: if !respond_to?(adapter_method) 82: raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter" 83: end 84: 85: remove_connection 86: establish_connection(ConnectionSpecification.new(spec, adapter_method)) 87: end 88: end
Returns true if a record exists in the table that matches the id or conditions given, or false otherwise. The argument can take five forms:
For more information about specifying conditions as a Hash or Array, see the Conditions section in the introduction to ActiveRecord::Base.
Note: You can‘t pass in a condition as a string (like name = ‘Jamie‘), since it would be sanitized and then queried against the primary key column, like id = ‘name = \’Jamie\’‘.
Person.exists?(5) Person.exists?('5') Person.exists?(:name => "David") Person.exists?(['name LIKE ?', "%#{query}%"]) Person.exists?
# File vendor/rails/activerecord/lib/active_record/base.rb, line 689 689: def exists?(id_or_conditions = {}) 690: find_initial( 691: :select => "#{quoted_table_name}.#{primary_key}", 692: :conditions => expand_id_conditions(id_or_conditions)) ? true : false 693: end
Find operates with four different retrieval approaches:
All approaches accept an options hash as their last parameter.
# find by id Person.find(1) # returns the object for ID = 1 Person.find(1, 2, 6) # returns an array for objects with IDs in (1, 2, 6) Person.find([7, 17]) # returns an array for objects with IDs in (7, 17) Person.find([1]) # returns an array for the object with ID = 1 Person.find(1, :conditions => "administrator = 1", :order => "created_on DESC")
Note that returned records may not be in the same order as the ids you provide since database rows are unordered. Give an explicit :order to ensure the results are sorted.
# find first Person.find(:first) # returns the first object fetched by SELECT * FROM people Person.find(:first, :conditions => [ "user_name = ?", user_name]) Person.find(:first, :conditions => [ "user_name = :u", { :u => user_name }]) Person.find(:first, :order => "created_on DESC", :offset => 5) # find last Person.find(:last) # returns the last object fetched by SELECT * FROM people Person.find(:last, :conditions => [ "user_name = ?", user_name]) Person.find(:last, :order => "created_on DESC", :offset => 5) # find all Person.find(:all) # returns an array of objects for all the rows fetched by SELECT * FROM people Person.find(:all, :conditions => [ "category IN (?)", categories], :limit => 50) Person.find(:all, :conditions => { :friends => ["Bob", "Steve", "Fred"] } Person.find(:all, :offset => 10, :limit => 10) Person.find(:all, :include => [ :account, :friends ]) Person.find(:all, :group => "category")
Example for find with a lock: Imagine two concurrent transactions: each will read person.visits == 2, add 1 to it, and save, resulting in two saves of person.visits = 3. By locking the row, the second transaction has to wait until the first is finished; we get the expected person.visits == 4.
Person.transaction do person = Person.find(1, :lock => true) person.visits += 1 person.save! end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 607 607: def find(*args) 608: options = args.extract_options! 609: validate_find_options(options) 610: set_readonly_option!(options) 611: 612: case args.first 613: when :first then find_initial(options) 614: when :last then find_last(options) 615: when :all then find_every(options) 616: else find_from_ids(args, options) 617: end 618: end
Executes a custom SQL query against your database and returns all the results. The results will be returned as an array with columns requested encapsulated as attributes of the model you call this method from. If you call Product.find_by_sql then the results will be returned in a Product object with the attributes you specified in the SQL query.
If you call a complicated SQL query which spans multiple tables the columns specified by the SELECT will be attributes of the model, whether or not they are columns of the corresponding table.
The sql parameter is a full SQL query as a string. It will be called as is, there will be no database agnostic conversions performed. This should be a last resort because using, for example, MySQL specific terms will lock you to using that particular database engine or require you to change your call if you switch engines.
# A simple SQL query spanning multiple tables Post.find_by_sql "SELECT p.title, c.author FROM posts p, comments c WHERE p.id = c.post_id" > [#<Post:0x36bff9c @attributes={"title"=>"Ruby Meetup", "first_name"=>"Quentin"}>, ...] # You can use the same string replacement techniques as you can with ActiveRecord#find Post.find_by_sql ["SELECT title FROM posts WHERE author = ? AND created > ?", author_id, start_date] > [#<Post:0x36bff9c @attributes={"first_name"=>"The Cheap Man Buys Twice"}>, ...]
# File vendor/rails/activerecord/lib/active_record/base.rb, line 660 660: def find_by_sql(sql) 661: connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) } 662: end
Transforms attribute key names into a more humane format, such as "First name" instead of "first_name". Example:
Person.human_attribute_name("first_name") # => "First name"
This used to be depricated in favor of humanize, but is now preferred, because it automatically uses the I18n module now. Specify options with additional translating options.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1361 1361: def human_attribute_name(attribute_key_name, options = {}) 1362: defaults = self_and_descendants_from_active_record.map do |klass| 1363: "#{klass.name.underscore}.#{attribute_key_name}""#{klass.name.underscore}.#{attribute_key_name}" 1364: end 1365: defaults << options[:default] if options[:default] 1366: defaults.flatten! 1367: defaults << attribute_key_name.to_s.humanize 1368: options[:count] ||= 1 1369: I18n.translate(defaults.shift, options.merge(:default => defaults, :scope => [:activerecord, :attributes])) 1370: end
Transform the modelname into a more humane format, using I18n. Defaults to the basic humanize method. Default scope of the translation is activerecord.models Specify options with additional translating options.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1376 1376: def human_name(options = {}) 1377: defaults = self_and_descendants_from_active_record.map do |klass| 1378: "#{klass.name.underscore}""#{klass.name.underscore}" 1379: end 1380: defaults << self.name.humanize 1381: I18n.translate(defaults.shift, {:scope => [:activerecord, :models], :count => 1, :default => defaults}.merge(options)) 1382: end
Increment a number field by one, usually representing a count.
This is used for caching aggregate values, so that they don‘t need to be computed every time. For example, a DiscussionBoard may cache post_count and comment_count otherwise every time the board is shown it would have to run an SQL query to find how many posts and comments there are.
# Increment the post_count column for the record with an id of 5 DiscussionBoard.increment_counter(:post_count, 5)
# File vendor/rails/activerecord/lib/active_record/base.rb, line 979 979: def increment_counter(counter_name, id) 980: update_counters(id, counter_name => 1) 981: end
Defines the column name for use with single table inheritance — can be set in subclasses like so: self.inheritance_column = "type_id"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1183 1183: def inheritance_column 1184: @inheritance_column ||= "type".freeze 1185: end
Returns a string like ‘Post id:integer, title:string, body:text‘
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1399 1399: def inspect 1400: if self == Base 1401: super 1402: elsif abstract_class? 1403: "#{super}(abstract)" 1404: elsif table_exists? 1405: attr_list = columns.map { |c| "#{c.name}: #{c.type}" } * ', ' 1406: "#{super}(#{attr_list})" 1407: else 1408: "#{super}(Table doesn't exist)" 1409: end 1410: end
Merges conditions so that the result is a valid condition
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1489 1489: def merge_conditions(*conditions) 1490: segments = [] 1491: 1492: conditions.each do |condition| 1493: unless condition.blank? 1494: sql = sanitize_sql(condition) 1495: segments << sql unless sql.blank? 1496: end 1497: end 1498: 1499: "(#{segments.join(') AND (')})" unless segments.empty? 1500: end
New objects can be instantiated as either empty (pass no construction parameter) or pre-set with attributes but not yet saved (pass a hash with key names matching the associated table column names). In both instances, valid attribute keys are determined by the column names of the associated table — hence you can‘t have attributes that aren‘t part of the table columns.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2433 2433: def initialize(attributes = nil) 2434: @attributes = attributes_from_column_definition 2435: @attributes_cache = {} 2436: @new_record = true 2437: ensure_proper_type 2438: self.attributes = attributes unless attributes.nil? 2439: self.class.send(:scope, :create).each { |att,value| self.send("#{att}=", value) } if self.class.send(:scoped?, :create) 2440: result = yield self if block_given? 2441: callback(:after_initialize) if respond_to_without_attributes?(:after_initialize) 2442: result 2443: end
Defines the primary key field — can be overridden in subclasses. Overwriting will negate any effect of the primary_key_prefix_type setting, though.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1160 1160: def primary_key 1161: reset_primary_key 1162: end
Returns an array of all the attributes that have been specified as readonly.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1072 1072: def readonly_attributes 1073: read_inheritable_attribute(:attr_readonly) 1074: end
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 131 131: def remove_connection(klass = self) 132: connection_handler.remove_connection(klass) 133: end
Resets all the cached information about columns, which will cause them to be reloaded on the next request.
The most common usage pattern for this method is probably in a migration, when just after creating a table you want to populate it with some default values, eg:
class CreateJobLevels < ActiveRecord::Migration def self.up create_table :job_levels do |t| t.integer :id t.string :name t.timestamps end JobLevel.reset_column_information %w{assistant executive manager director}.each do |type| JobLevel.create(:name => type) end end def self.down drop_table :job_levels end end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1333 1333: def reset_column_information 1334: generated_methods.each { |name| undef_method(name) } 1335: @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @generated_methods = @inheritance_column = nil 1336: end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1474 1474: def respond_to?(method_id, include_private = false) 1475: if match = DynamicFinderMatch.match(method_id) 1476: return true if all_attributes_exists?(match.attribute_names) 1477: elsif match = DynamicScopeMatch.match(method_id) 1478: return true if all_attributes_exists?(match.attribute_names) 1479: end 1480: 1481: super 1482: end
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 122 122: def retrieve_connection 123: connection_handler.retrieve_connection(self) 124: end
If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object, then specify the name of that attribute using this method and it will be handled automatically. The serialization is done through YAML. If class_name is specified, the serialized object must be of that class on retrieval or SerializationTypeMismatch will be raised.
# Serialize a preferences attribute class User serialize :preferences end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1091 1091: def serialize(attr_name, class_name = Object) 1092: serialized_attributes[attr_name.to_s] = class_name 1093: end
Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1096 1096: def serialized_attributes 1097: read_inheritable_attribute(:attr_serialized) or write_inheritable_attribute(:attr_serialized, {}) 1098: end
Sets the name of the inheritance column to use to the given value, or (if the value # is nil or false) to the value returned by the given block.
class Project < ActiveRecord::Base set_inheritance_column do original_inheritance_column + "_id" end end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1231 1231: def set_inheritance_column(value = nil, &block) 1232: define_attr_method :inheritance_column, value, &block 1233: end
Sets the name of the primary key column to use to the given value, or (if the value is nil or false) to the value returned by the given block.
class Project < ActiveRecord::Base set_primary_key "sysid" end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1217 1217: def set_primary_key(value = nil, &block) 1218: define_attr_method :primary_key, value, &block 1219: end
Sets the name of the sequence to use when generating ids to the given value, or (if the value is nil or false) to the value returned by the given block. This is required for Oracle and is useful for any database which relies on sequences for primary key generation.
If a sequence name is not explicitly set when using Oracle or Firebird, it will default to the commonly used pattern of: #{table_name}_seq
If a sequence name is not explicitly set when using PostgreSQL, it will discover the sequence corresponding to your primary key for you.
class Project < ActiveRecord::Base set_sequence_name "projectseq" # default would have been "project_seq" end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1250 1250: def set_sequence_name(value = nil, &block) 1251: define_attr_method :sequence_name, value, &block 1252: end
Sets the table name to use to the given value, or (if the value is nil or false) to the value returned by the given block.
class Project < ActiveRecord::Base set_table_name "project" end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1205 1205: def set_table_name(value = nil, &block) 1206: define_attr_method :table_name, value, &block 1207: end
Silences the logger for the duration of the block.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1446 1446: def silence 1447: old_logger_level, logger.level = logger.level, Logger::ERROR if logger 1448: yield 1449: ensure 1450: logger.level = old_logger_level if logger 1451: end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1484 1484: def sti_name 1485: store_full_sti_class ? name : name.demodulize 1486: end
Indicates whether the table associated with this class exists
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1264 1264: def table_exists? 1265: connection.table_exists?(table_name) 1266: end
Guesses the table name (in forced lower-case) based on the name of the class in the inheritance hierarchy descending directly from ActiveRecord::Base. So if the hierarchy looks like: Reply < Message < ActiveRecord::Base, then Message is used to guess the table name even when called on Reply. The rules used to do the guess are handled by the Inflector class in Active Support, which knows almost all common English inflections. You can add new inflections in config/initializers/inflections.rb.
Nested classes are given table names prefixed by the singular form of the parent‘s table name. Enclosing modules are not considered.
class Invoice < ActiveRecord::Base; end; file class table_name invoice.rb Invoice invoices class Invoice < ActiveRecord::Base; class Lineitem < ActiveRecord::Base; end; end; file class table_name invoice.rb Invoice::Lineitem invoice_lineitems module Invoice; class Lineitem < ActiveRecord::Base; end; end; file class table_name invoice/lineitem.rb Invoice::Lineitem lineitems
Additionally, the class-level table_name_prefix is prepended and the table_name_suffix is appended. So if you have "myapp_" as a prefix, the table name guess for an Invoice class becomes "myapp_invoices". Invoice::Lineitem becomes "myapp_invoice_lineitems".
You can also overwrite this class method to allow for unguessable links, such as a Mouse class with a link to a "mice" table. Example:
class Mouse < ActiveRecord::Base set_table_name "mice" end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1133 1133: def table_name 1134: reset_table_name 1135: end
Updates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.
# Updating one record: Person.update(15, :user_name => 'Samuel', :group => 'expert') # Updating multiple records: people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } } Person.update(people.keys, people.values)
# File vendor/rails/activerecord/lib/active_record/base.rb, line 744 744: def update(id, attributes) 745: if id.is_a?(Array) 746: idx = -1 747: id.collect { |one_id| idx += 1; update(one_id, attributes[idx]) } 748: else 749: object = find(id) 750: object.update_attributes(attributes) 751: object 752: end 753: end
Updates all records with details given if they match a set of conditions supplied, limits and order can also be supplied. This method constructs a single SQL UPDATE statement and sends it straight to the database. It does not instantiate the involved models and it does not trigger Active Record callbacks.
# Update all billing objects with the 3 different attributes given Billing.update_all( "category = 'authorized', approved = 1, author = 'David'" ) # Update records that match our conditions Billing.update_all( "author = 'David'", "title LIKE '%Rails%'" ) # Update records that match our conditions but limit it to 5 ordered by date Billing.update_all( "author = 'David'", "title LIKE '%Rails%'", :order => 'created_at', :limit => 5 )
# File vendor/rails/activerecord/lib/active_record/base.rb, line 827 827: def update_all(updates, conditions = nil, options = {}) 828: sql = "UPDATE #{quoted_table_name} SET #{sanitize_sql_for_assignment(updates)} " 829: 830: scope = scope(:find) 831: 832: select_sql = "" 833: add_conditions!(select_sql, conditions, scope) 834: 835: if options.has_key?(:limit) || (scope && scope[:limit]) 836: # Only take order from scope if limit is also provided by scope, this 837: # is useful for updating a has_many association with a limit. 838: add_order!(select_sql, options[:order], scope) 839: 840: add_limit!(select_sql, options, scope) 841: sql.concat(connection.limited_update_conditions(select_sql, quoted_table_name, connection.quote_column_name(primary_key))) 842: else 843: add_order!(select_sql, options[:order], nil) 844: sql.concat(select_sql) 845: end 846: 847: connection.update(sql, "#{name} Update") 848: end
A generic "counter updater" implementation, intended primarily to be used by increment_counter and decrement_counter, but which may also be useful on its own. It simply does a direct SQL update for the record with the given ID, altering the given hash of counters by the amount given by the corresponding value:
# For the Post with id of 5, decrement the comment_count by 1, and # increment the action_count by 1 Post.update_counters 5, :comment_count => -1, :action_count => 1 # Executes the following SQL: # UPDATE posts # SET comment_count = comment_count - 1, # action_count = action_count + 1 # WHERE id = 5 # For the Posts with id of 10 and 15, increment the comment_count by 1 Post.update_counters [10, 15], :comment_count => 1 # Executes the following SQL: # UPDATE posts # SET comment_count = comment_count + 1, # WHERE id IN (10, 15)
# File vendor/rails/activerecord/lib/active_record/base.rb, line 948 948: def update_counters(id, counters) 949: updates = counters.inject([]) { |list, (counter_name, increment)| 950: sign = increment < 0 ? "-" : "+" 951: list << "#{connection.quote_column_name(counter_name)} = COALESCE(#{connection.quote_column_name(counter_name)}, 0) #{sign} #{increment.abs}" 952: }.join(", ") 953: 954: if id.is_a?(Array) 955: ids_list = id.map {|i| quote_value(i)}.join(', ') 956: condition = "IN (#{ids_list})" 957: else 958: condition = "= #{quote_value(id)}" 959: end 960: 961: update_all(updates, "#{connection.quote_column_name(primary_key)} #{condition}") 962: end
Deprecated and no longer has any effect.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 102 102: def verification_timeout 103: ActiveSupport::Deprecation.warn("ActiveRecord::Base.verification_timeout has been deprecated and no longer has any effect. Please remove all references to verification_timeout.") 104: end
Deprecated and no longer has any effect.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 107 107: def verification_timeout=(flag) 108: ActiveSupport::Deprecation.warn("ActiveRecord::Base.verification_timeout= has been deprecated and no longer has any effect. Please remove all references to verification_timeout=.") 109: end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2248 2248: def aggregate_mapping(reflection) 2249: mapping = reflection.options[:mapping] || [reflection.name, reflection.name] 2250: mapping.first.is_a?(Array) ? mapping : [mapping] 2251: end
Returns the class descending directly from ActiveRecord::Base or an abstract class, if any, in the inheritance hierarchy.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2206 2206: def class_of_active_record_descendant(klass) 2207: if klass.superclass == Base || klass.superclass.abstract_class? 2208: klass 2209: elsif klass.superclass.nil? 2210: raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord" 2211: else 2212: class_of_active_record_descendant(klass.superclass) 2213: end 2214: end
Returns the class type of the record using the current module as a prefix. So descendants of MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2193 2193: def compute_type(type_name) 2194: modularized_name = type_name_with_module(type_name) 2195: silence_warnings do 2196: begin 2197: class_eval(modularized_name, __FILE__, __LINE__) 2198: rescue NameError 2199: class_eval(type_name, __FILE__, __LINE__) 2200: end 2201: end 2202: end
Sets the default options for the model. The format of the options argument is the same as in find.
class Person < ActiveRecord::Base default_scope :order => 'last_name, first_name' end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2165 2165: def default_scope(options = {}) 2166: self.default_scoping << { :find => options, :create => options[:conditions].is_a?(Hash) ? options[:conditions] : {} } 2167: end
Accepts a hash of SQL conditions and replaces those attributes that correspond to a composed_of relationship with their expanded aggregate attribute values. Given:
class Person < ActiveRecord::Base composed_of :address, :class_name => "Address", :mapping => [%w(address_street street), %w(address_city city)] end
Then:
{ :address => Address.new("813 abc st.", "chicago") } # => { :address_street => "813 abc st.", :address_city => "chicago" }
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2264 2264: def expand_hash_conditions_for_aggregates(attrs) 2265: expanded_attrs = {} 2266: attrs.each do |attr, value| 2267: unless (aggregation = reflect_on_aggregation(attr.to_sym)).nil? 2268: mapping = aggregate_mapping(aggregation) 2269: mapping.each do |field_attr, aggregate_attr| 2270: if mapping.size == 1 && !value.respond_to?(aggregate_attr) 2271: expanded_attrs[field_attr] = value 2272: else 2273: expanded_attrs[field_attr] = value.send(aggregate_attr) 2274: end 2275: end 2276: else 2277: expanded_attrs[attr] = value 2278: end 2279: end 2280: expanded_attrs 2281: end
Accepts an array of conditions. The array has each value sanitized and interpolated into the SQL statement.
["name='%s' and group_id='%s'", "foo'bar", 4] returns "name='foo''bar' and group_id='4'"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2336 2336: def sanitize_sql_array(ary) 2337: statement, *values = ary 2338: if values.first.is_a?(Hash) and statement =~ /:\w+/ 2339: replace_named_bind_variables(statement, values.first) 2340: elsif statement.include?('?') 2341: replace_bind_variables(statement, values) 2342: else 2343: statement % values.collect { |value| connection.quote_string(value.to_s) } 2344: end 2345: end
Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a SET clause.
{ :name => nil, :group_id => 4 } returns "name = NULL , group_id='4'"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2240 2240: def sanitize_sql_for_assignment(assignments) 2241: case assignments 2242: when Array; sanitize_sql_array(assignments) 2243: when Hash; sanitize_sql_hash_for_assignment(assignments) 2244: else assignments 2245: end 2246: end
Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a WHERE clause.
["name='%s' and group_id='%s'", "foo'bar", 4] returns "name='foo''bar' and group_id='4'" { :name => "foo'bar", :group_id => 4 } returns "name='foo''bar' and group_id='4'" "name='foo''bar' and group_id='4'" returns "name='foo''bar' and group_id='4'"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2226 2226: def sanitize_sql_for_conditions(condition, table_name = quoted_table_name) 2227: return nil if condition.blank? 2228: 2229: case condition 2230: when Array; sanitize_sql_array(condition) 2231: when Hash; sanitize_sql_hash_for_conditions(condition, table_name) 2232: else condition 2233: end 2234: end
Sanitizes a hash of attribute/value pairs into SQL conditions for a SET clause.
{ :status => nil, :group_id => 1 } # => "status = NULL , group_id = 1"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2327 2327: def sanitize_sql_hash_for_assignment(attrs) 2328: attrs.map do |attr, value| 2329: "#{connection.quote_column_name(attr)} = #{quote_bound_value(value)}" 2330: end.join(', ') 2331: end
Sanitizes a hash of attribute/value pairs into SQL conditions for a WHERE clause.
{ :name => "foo'bar", :group_id => 4 } # => "name='foo''bar' and group_id= 4" { :status => nil, :group_id => [1,2,3] } # => "status IS NULL and group_id IN (1,2,3)" { :age => 13..18 } # => "age BETWEEN 13 AND 18" { 'other_records.id' => 7 } # => "`other_records`.`id` = 7" { :other_records => { :id => 7 } } # => "`other_records`.`id` = 7"
And for value objects on a composed_of relationship:
{ :address => Address.new("123 abc st.", "chicago") } # => "address_street='123 abc st.' and address_city='chicago'"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2297 2297: def sanitize_sql_hash_for_conditions(attrs, default_table_name = quoted_table_name) 2298: attrs = expand_hash_conditions_for_aggregates(attrs) 2299: 2300: conditions = attrs.map do |attr, value| 2301: table_name = default_table_name 2302: 2303: unless value.is_a?(Hash) 2304: attr = attr.to_s 2305: 2306: # Extract table name from qualified attribute names. 2307: if attr.include?('.') 2308: attr_table_name, attr = attr.split('.', 2) 2309: attr_table_name = connection.quote_table_name(attr_table_name) 2310: else 2311: attr_table_name = table_name 2312: end 2313: 2314: attribute_condition("#{attr_table_name}.#{connection.quote_column_name(attr)}", value) 2315: else 2316: sanitize_sql_hash_for_conditions(value, connection.quote_table_name(attr.to_s)) 2317: end 2318: end.join(' AND ') 2319: 2320: replace_bind_variables(conditions, expand_range_bind_variables(attrs.values)) 2321: end
Works like with_scope, but discards any nested properties.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2150 2150: def with_exclusive_scope(method_scoping = {}, &block) 2151: with_scope(method_scoping, :overwrite, &block) 2152: end
Scope parameters to method calls within the block. Takes a hash of method_name => parameters hash. method_name may be :find or :create. :find parameters may include the :conditions, :joins, :include, :offset, :limit, and :readonly options. :create parameters are an attributes hash.
class Article < ActiveRecord::Base def self.create_with_scope with_scope(:find => { :conditions => "blog_id = 1" }, :create => { :blog_id => 1 }) do find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1 a = create(1) a.blog_id # => 1 end end end
In nested scopings, all previous parameters are overwritten by the innermost rule, with the exception of :conditions, :include, and :joins options in :find, which are merged.
:joins options are uniqued so multiple scopes can join in the same table without table aliasing problems. If you need to join multiple tables, but still want one of the tables to be uniqued, use the array of strings format for your joins.
class Article < ActiveRecord::Base def self.find_with_scope with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }, :create => { :blog_id => 1 }) do with_scope(:find => { :limit => 10 }) find(:all) # => SELECT * from articles WHERE blog_id = 1 LIMIT 10 end with_scope(:find => { :conditions => "author_id = 3" }) find(:all) # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1 end end end end
You can ignore any previous scopings by using the with_exclusive_scope method.
class Article < ActiveRecord::Base def self.find_with_exclusive_scope with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }) do with_exclusive_scope(:find => { :limit => 10 }) find(:all) # => SELECT * from articles LIMIT 10 end end end end
Note: the +:find+ scope also has effect on update and deletion methods, like update_all and delete_all.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2089 2089: def with_scope(method_scoping = {}, action = :merge, &block) 2090: method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping) 2091: 2092: # Dup first and second level of hash (method and params). 2093: method_scoping = method_scoping.inject({}) do |hash, (method, params)| 2094: hash[method] = (params == true) ? params : params.dup 2095: hash 2096: end 2097: 2098: method_scoping.assert_valid_keys([ :find, :create ]) 2099: 2100: if f = method_scoping[:find] 2101: f.assert_valid_keys(VALID_FIND_OPTIONS) 2102: set_readonly_option! f 2103: end 2104: 2105: # Merge scopings 2106: if [:merge, :reverse_merge].include?(action) && current_scoped_methods 2107: method_scoping = current_scoped_methods.inject(method_scoping) do |hash, (method, params)| 2108: case hash[method] 2109: when Hash 2110: if method == :find 2111: (hash[method].keys + params.keys).uniq.each do |key| 2112: merge = hash[method][key] && params[key] # merge if both scopes have the same key 2113: if key == :conditions && merge 2114: if params[key].is_a?(Hash) && hash[method][key].is_a?(Hash) 2115: hash[method][key] = merge_conditions(hash[method][key].deep_merge(params[key])) 2116: else 2117: hash[method][key] = merge_conditions(params[key], hash[method][key]) 2118: end 2119: elsif key == :include && merge 2120: hash[method][key] = merge_includes(hash[method][key], params[key]).uniq 2121: elsif key == :joins && merge 2122: hash[method][key] = merge_joins(params[key], hash[method][key]) 2123: else 2124: hash[method][key] = hash[method][key] || params[key] 2125: end 2126: end 2127: else 2128: if action == :reverse_merge 2129: hash[method] = hash[method].merge(params) 2130: else 2131: hash[method] = params.merge(hash[method]) 2132: end 2133: end 2134: else 2135: hash[method] = params 2136: end 2137: hash 2138: end 2139: end 2140: 2141: self.scoped_methods << method_scoping 2142: begin 2143: yield 2144: ensure 2145: self.scoped_methods.pop 2146: end 2147: end
Returns true if the comparison_object is the same object, or is of the same type and has the same id.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2817 2817: def ==(comparison_object) 2818: comparison_object.equal?(self) || 2819: (comparison_object.instance_of?(self.class) && 2820: comparison_object.id == id && 2821: !comparison_object.new_record?) 2822: end
Returns the value of the attribute identified by attr_name after it has been typecast (for example, "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)). (Alias for the protected read_attribute method).
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2704 2704: def [](attr_name) 2705: read_attribute(attr_name) 2706: end
Updates the attribute identified by attr_name with the specified value. (Alias for the protected write_attribute method).
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2710 2710: def []=(attr_name, value) 2711: write_attribute(attr_name, value) 2712: end
Returns an inspect-like string for the value of the attribute attr_name. String attributes are elided after 50 characters, and Date and Time attributes are returned in the :db format. Other attributes return the value of inspect without modification.
person = Person.create!(:name => "David Heinemeier Hansson " * 3) person.attribute_for_inspect(:name) # => '"David Heinemeier Hansson David Heinemeier Hansson D..."' person.attribute_for_inspect(:created_at) # => '"2009-01-12 04:48:57"'
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2782 2782: def attribute_for_inspect(attr_name) 2783: value = read_attribute(attr_name) 2784: 2785: if value.is_a?(String) && value.length > 50 2786: "#{value[0..50]}...".inspect 2787: elsif value.is_a?(Date) || value.is_a?(Time) 2788: %("#{value.to_s(:db)}") 2789: else 2790: value.inspect 2791: end 2792: end
Returns an array of names for the attributes available on this object sorted alphabetically.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2807 2807: def attribute_names 2808: @attributes.keys.sort 2809: end
Returns true if the specified attribute has been set by the user or by a database load and is neither nil nor empty? (the latter only applies to objects that respond to empty?, most notably Strings).
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2796 2796: def attribute_present?(attribute) 2797: value = read_attribute(attribute) 2798: !value.blank? 2799: end
Returns a hash of all the attributes with their names as keys and the values of the attributes as values.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2754 2754: def attributes 2755: self.attribute_names.inject({}) do |attrs, name| 2756: attrs[name] = read_attribute(name) 2757: attrs 2758: end 2759: end
Allows you to set all the attributes at once by passing in a hash with keys matching the attribute names (which again matches the column names).
If guard_protected_attributes is true (the default), then sensitive attributes can be protected from this form of mass-assignment by using the attr_protected macro. Or you can alternatively specify which attributes can be accessed with the attr_accessible macro. Then all the attributes not included in that won‘t be allowed to be mass-assigned.
class User < ActiveRecord::Base attr_protected :is_admin end user = User.new user.attributes = { :username => 'Phusion', :is_admin => true } user.username # => "Phusion" user.is_admin? # => false user.send(:attributes=, { :username => 'Phusion', :is_admin => true }, false) user.is_admin? # => true
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2734 2734: def attributes=(new_attributes, guard_protected_attributes = true) 2735: return if new_attributes.nil? 2736: attributes = new_attributes.dup 2737: attributes.stringify_keys! 2738: 2739: multi_parameter_attributes = [] 2740: attributes = remove_attributes_protected_from_mass_assignment(attributes) if guard_protected_attributes 2741: 2742: attributes.each do |k, v| 2743: if k.include?("(") 2744: multi_parameter_attributes << [ k, v ] 2745: else 2746: respond_to?("#{k}=""#{k}=") ? send("#{k}=""#{k}=", v) : raise(UnknownAttributeError, "unknown attribute: #{k}") 2747: end 2748: end 2749: 2750: assign_multiparameter_attributes(multi_parameter_attributes) 2751: end
Returns a hash of attributes before typecasting and deserialization.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2762 2762: def attributes_before_type_cast 2763: self.attribute_names.inject({}) do |attrs, name| 2764: attrs[name] = read_attribute_before_type_cast(name) 2765: attrs 2766: end 2767: end
Returns an instance of the specified klass with the attributes of the current record. This is mostly useful in relation to single-table inheritance structures where you want a subclass to appear as the superclass. This can be used along with record identification in Action Pack to allow, say, Client < Company to do something like render :partial => @client.becomes(Company) to render that instance using the companies/company partial instead of clients/client.
Note: The new instance will share a link to the same attributes as the original class. So any change to the attributes in either instance will affect the other.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2609 2609: def becomes(klass) 2610: returning klass.new do |became| 2611: became.instance_variable_set("@attributes", @attributes) 2612: became.instance_variable_set("@attributes_cache", @attributes_cache) 2613: became.instance_variable_set("@new_record", new_record?) 2614: end 2615: end
Returns a cache key that can be used to identify this record.
Product.new.cache_key # => "products/new" Product.find(5).cache_key # => "products/5" (updated_at not available) Person.find(5).cache_key # => "people/5-20071224150000" (updated_at available)
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2491 2491: def cache_key 2492: case 2493: when new_record? 2494: "#{self.class.model_name.cache_key}/new" 2495: when timestamp = self[:updated_at] 2496: "#{self.class.model_name.cache_key}/#{id}-#{timestamp.to_s(:number)}" 2497: else 2498: "#{self.class.model_name.cache_key}/#{id}" 2499: end 2500: end
Returns a clone of the record that hasn‘t been assigned an id yet and is treated as a new record. Note that this is a "shallow" clone: it copies the object‘s attributes only, not its associations. The extent of a "deep" clone is application-specific and is therefore left to the application to implement according to its need.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2594 2594: def clone 2595: attrs = clone_attributes(:read_attribute_before_type_cast) 2596: attrs.delete(self.class.primary_key) 2597: record = self.class.new 2598: record.send :instance_variable_set, '@attributes', attrs 2599: record 2600: end
Returns the column object for the named attribute.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2812 2812: def column_for_attribute(name) 2813: self.class.columns_hash[name.to_s] 2814: end
Returns the connection currently associated with the class. This can also be used to "borrow" the connection to do database work that isn‘t easily done without going straight to SQL.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 19 19: def connection 20: self.class.connection 21: end
Initializes attribute to zero if nil and subtracts the value passed as by (default is 1). The decrement is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2658 2658: def decrement(attribute, by = 1) 2659: self[attribute] ||= 0 2660: self[attribute] -= by 2661: self 2662: end
Wrapper around decrement that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2668 2668: def decrement!(attribute, by = 1) 2669: decrement(attribute, by).update_attribute(attribute, self[attribute]) 2670: end
Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can‘t be persisted). Returns the frozen instance.
The row is simply removed with a SQL DELETE statement on the record‘s primary key, and no callbacks are executed.
To enforce the object‘s before_destroy and after_destroy callbacks, Observer methods, or any :dependent association options, use destroy.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2568 2568: def delete 2569: self.class.delete(id) unless new_record? 2570: @destroyed = true 2571: freeze 2572: end
Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can‘t be persisted).
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2576 2576: def destroy 2577: unless new_record? 2578: connection.delete( 2579: "DELETE FROM #{self.class.quoted_table_name} " + 2580: "WHERE #{connection.quote_column_name(self.class.primary_key)} = #{quoted_id}", 2581: "#{self.class.name} Destroy" 2582: ) 2583: end 2584: 2585: @destroyed = true 2586: freeze 2587: end
Returns true if the record has been destroyed.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2846 2846: def destroyed? 2847: @destroyed 2848: end
Delegates to ==
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2825 2825: def eql?(comparison_object) 2826: self == (comparison_object) 2827: end
Freeze the attributes hash such that associations are still accessible, even on destroyed records.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2836 2836: def freeze 2837: @attributes.freeze; self 2838: end
Returns true if the attributes hash has been frozen.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2841 2841: def frozen? 2842: @attributes.frozen? 2843: end
Returns true if the given attribute is in the attributes hash
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2802 2802: def has_attribute?(attr_name) 2803: @attributes.has_key?(attr_name.to_s) 2804: end
Delegates to id in order to allow two records of the same type and id to work with something like:
[ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2831 2831: def hash 2832: id.hash 2833: end
A model instance‘s primary key is always available as model.id whether you name it the default ‘id’ or set it to something else.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2447 2447: def id 2448: attr_name = self.class.primary_key 2449: column = column_for_attribute(attr_name) 2450: 2451: self.class.send(:define_read_method, :id, attr_name, column) 2452: # now that the method exists, call it 2453: self.send attr_name.to_sym 2454: 2455: end
Sets the primary ID.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2511 2511: def id=(value) 2512: write_attribute(self.class.primary_key, value) 2513: end
Initializes attribute to zero if nil and adds the value passed as by (default is 1). The increment is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2641 2641: def increment(attribute, by = 1) 2642: self[attribute] ||= 0 2643: self[attribute] += by 2644: self 2645: end
Wrapper around increment that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2651 2651: def increment!(attribute, by = 1) 2652: increment(attribute, by).update_attribute(attribute, self[attribute]) 2653: end
Returns the contents of the record as a nicely formatted string.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2862 2862: def inspect 2863: attributes_as_nice_string = self.class.column_names.collect { |name| 2864: if has_attribute?(name) || new_record? 2865: "#{name}: #{attribute_for_inspect(name)}" 2866: end 2867: }.compact.join(", ") 2868: "#<#{self.class} #{attributes_as_nice_string}>" 2869: end
Returns true if this object hasn‘t been saved yet — that is, a record for the object doesn‘t exist yet; otherwise, returns false.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2516 2516: def new_record? 2517: @new_record || false 2518: end
Marks this record as read only.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2857 2857: def readonly! 2858: @readonly = true 2859: end
Returns true if the record is read only. Records loaded through joins with piggy-back attributes will be marked as read only since they cannot be saved.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2852 2852: def readonly? 2853: defined?(@readonly) && @readonly == true 2854: end
Reloads the attributes of this object from the database. The optional options argument is passed to find when reloading so you may do e.g. record.reload(:lock => true) to reload the same record with an exclusive row lock.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2693 2693: def reload(options = nil) 2694: clear_aggregation_cache 2695: clear_association_cache 2696: @attributes.update(self.class.find(self.id, options).instance_variable_get('@attributes')) 2697: @attributes_cache = {} 2698: self 2699: end
Saves the model.
If the model is new a record gets created in the database, otherwise the existing record gets updated.
If perform_validation is true validations run. If any of them fail the action is cancelled and save returns false. If the flag is false validations are bypassed altogether. See ActiveRecord::Validations for more information.
There‘s a series of callbacks associated with save. If any of the before_* callbacks return false the action is cancelled and save returns false. See ActiveRecord::Callbacks for further details.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2537 2537: def save 2538: create_or_update 2539: end
Saves the model.
If the model is new a record gets created in the database, otherwise the existing record gets updated.
With save! validations always run. If any of them fail ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations for more information.
There‘s a series of callbacks associated with save!. If any of the before_* callbacks return false the action is cancelled and save! raises ActiveRecord::RecordNotSaved. See ActiveRecord::Callbacks for further details.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2554 2554: def save! 2555: create_or_update || raise(RecordNotSaved) 2556: end
Returns a String, which Action Pack uses for constructing an URL to this object. The default implementation returns this record‘s id as a String, or nil if this record‘s unsaved.
For example, suppose that you have a User model, and that you have a map.resources :users route. Normally, user_path will construct a path with the user object‘s ‘id’ in it:
user = User.find_by_name('Phusion') user_path(user) # => "/users/1"
You can override to_param in your model to make user_path construct a path using the user‘s name instead of the user‘s id:
class User < ActiveRecord::Base def to_param # overridden name end end user = User.find_by_name('Phusion') user_path(user) # => "/users/Phusion"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2479 2479: def to_param 2480: # We can't use alias_method here, because method 'id' optimizes itself on the fly. 2481: (id = self.id) ? id.to_s : nil # Be sure to stringify the id for routes 2482: end
Assigns to attribute the boolean opposite of attribute?. So if the predicate returns true the attribute will become false. This method toggles directly the underlying value without calling any setter. Returns self.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2676 2676: def toggle(attribute) 2677: self[attribute] = !send("#{attribute}?") 2678: self 2679: end
Wrapper around toggle that saves the record. This method differs from its non-bang version in that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2685 2685: def toggle!(attribute) 2686: toggle(attribute).update_attribute(attribute, self[attribute]) 2687: end
Updates a single attribute and saves the record without going through the normal validation procedure. This is especially useful for boolean flags on existing records. The regular update_attribute method in Base is replaced with this when the validations module is mixed in, which it is by default.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2620 2620: def update_attribute(name, value) 2621: send(name.to_s + '=', value) 2622: save(false) 2623: end
Updates all the attributes from the passed-in Hash and saves the record. If the object is invalid, the saving will fail and false will be returned.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2627 2627: def update_attributes(attributes) 2628: self.attributes = attributes 2629: save 2630: end
Updates an object just like Base.update_attributes but calls save! instead of save so an exception is raised if the record is invalid.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 2633 2633: def update_attributes!(attributes) 2634: self.attributes = attributes 2635: save! 2636: end