Active Record objects doesn’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 accepts 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 a 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 or an array 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 doesn’t involve tainted data. Examples:
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 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 a HTTP request. The authenticate_safely method, on the other hand, 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, [ "id = :id AND name = :name AND division = :division AND created_at > :accounting_date", { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' } ])
All column values are automatically available through basic accessors on the Active Record object, but some times you want to specialize this behavior. This can be done by either by overwriting the default accessors (using the same name as the attribute) 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 * 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, vaule) and read_attribute(:attribute) as a shorter form.
Some times you want to be able to read the raw attribute data without having the column-determined type cast 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 type cast the string to 0, which isn’t what you want.
Dynamic attribute-based finders are a cleaner way of getting objects by simple queries without turning to SQL. They work by appending the name of an attribute to find_by_ or find_all_by_, so you get finders like Person.find_by_user_name, Person.find_all_by_last_name, Payment.find_by_transaction_id. So instead of writing Person.find(:first, ["user_name = ?", user_name]), you just do Person.find_by_user_name(user_name). And instead of writing Person.find(:all, ["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, ["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").
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-mappeable 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 an class option as the second parameter that’ll raise an exception if a serialized object is retrieved as a descendent 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 called "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 a ActiveRecord::Base, but resides in a different database you can just say Course.establish_connection and Course *and all 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.
set_table_name | -> | table_name= |
set_primary_key | -> | primary_key= |
set_inheritance_column | -> | inheritance_column= |
sanitize_sql | -> | sanitize_conditions |
respond_to? | -> | respond_to_without_attributes? |
For checking respond_to? without searching the attributes (which is faster). |
Overwrite the default class equality method to provide support for association proxies.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 714 714: def ===(object) 715: object.is_a?(self) 716: end
If this macro is used, only those attributed named in it will be accessible for mass-assignment, such as new(attributes) and attributes=(attributes). This is the more conservative choice for mass-assignment protection. If you’d rather start from an all-open default and restrict attributes as needed, have a look at attr_protected.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 512 512: def attr_accessible(*attributes) 513: write_inheritable_array("attr_accessible", attributes) 514: end
Attributes named in this macro are protected from mass-assignment, such as new(attributes) and attributes=(attributes). Their assignment will simply be ignored. Instead, you can use the direct writer methods to do assignment. This is meant to protect sensitive attributes to be overwritten by URL/form hackers. Example:
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"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 499 499: def attr_protected(*attributes) 500: write_inheritable_array("attr_protected", attributes) 501: end
Log and benchmark multiple statements in a single block. Usage (hides all the SQL calls for the individual actions and calculates total runtime for them all):
Project.benchmark("Creating project") do project = Project.create("name" => "stuff") project.create_manager("name" => "David") project.milestones << Milestone.find(:all) end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 698 698: def benchmark(title) 699: result = nil 700: seconds = Benchmark.realtime { result = silence { yield } } 701: logger.info "#{title} (#{sprintf("%f", seconds)})" if logger 702: return result 703: end
Returns a hash of all the methods added to query each of the columns in the table with the name of the method as the key and true as the value. This makes it possible to do O(1) lookups in respond_to? to check if a given method for attribute is available.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 651 651: def column_methods_hash 652: @dynamic_methods_hash ||= column_names.inject(Hash.new(false)) do |methods, attr| 653: methods[attr.to_sym] = true 654: methods["#{attr}=".to_sym] = true 655: methods["#{attr}?".to_sym] = true 656: methods["#{attr}_before_type_cast".to_sym] = true 657: methods 658: end 659: end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 638 638: def column_names 639: @column_names ||= columns.map { |column| column.name } 640: end
Returns an array of column objects for the table associated with this class.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 629 629: def columns 630: @columns ||= connection.columns(table_name, "#{name} Columns") 631: end
Returns an array of column objects for the table associated with this class.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 634 634: def columns_hash 635: @columns_hash ||= columns.inject({}) { |hash, column| hash[column.name] = column; hash } 636: end
Returns true if a connection that’s accessible to this class have already been opened.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 117 117: def self.connected? 118: klass = self 119: until klass == ActiveRecord::Base.superclass 120: if active_connections[klass] 121: return true 122: else 123: klass = klass.superclass 124: end 125: end 126: return false 127: 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/base.rb, line 238 238: def self.connection 239: retrieve_connection 240: end
Set the connection for the class.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 141 141: def self.connection=(spec) 142: raise ConnectionNotEstablished unless spec 143: conn = self.send(spec.adapter_method, spec.config) 144: active_connections[self] = conn 145: end
Set the connection for the class with caching on
# File vendor/rails/activerecord/lib/active_record/query_cache.rb, line 47 47: def self.connection=(spec) 48: raise ConnectionNotEstablished unless spec 49: 50: conn = spec.config[:query_cache] ? 51: QueryCache.new(self.send(spec.adapter_method, spec.config)) : 52: self.send(spec.adapter_method, spec.config) 53: 54: active_connections[self] = conn 55: end
Returns an array of columns objects where the primary id, all columns ending in "_id" or "_count", and columns used for single table inheritance has been removed.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 644 644: def content_columns 645: @content_columns ||= columns.reject { |c| c.name == primary_key || c.name =~ /(_id|_count)$/ || c.name == inheritance_column } 646: end
Returns the number of records that meets the conditions. Zero is returned if no records match. Example:
Product.count "sales > 1"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 450 450: def count(conditions = nil, joins = nil) 451: sql = "SELECT COUNT(*) FROM #{table_name} " 452: sql << " #{joins} " if joins 453: add_conditions!(sql, conditions) 454: count_by_sql(sql) 455: end
Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part.
Product.count "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 459 459: def count_by_sql(sql) 460: sql = sanitize_conditions(sql) 461: rows = connection.select_one(sql, "#{name} Count") 462: 463: if !rows.nil? and count = rows.values.first 464: count.to_i 465: else 466: 0 467: end 468: end
Creates an object, instantly saves it as a record (if the validation permits it), and returns it. If the save fail under validations, the unsaved object is still returned.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 388 388: def create(attributes = nil) 389: if attributes.is_a?(Array) 390: attributes.collect { |attr| create(attr) } 391: else 392: object = new(attributes) 393: object.save 394: object 395: end 396: end
Works like increment_counter, but decrements instead.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 480 480: def decrement_counter(counter_name, id) 481: update_all "#{counter_name} = #{counter_name} - 1", "#{primary_key} = #{quote(id)}" 482: end
Deletes the record with the given id without instantiating an object first. If an array of ids is provided, all of them are deleted.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 413 413: def delete(id) 414: delete_all([ "#{primary_key} IN (?)", id ]) 415: end
Deletes all the records that matches the condition without instantiating the objects first (and hence not calling the destroy method). Example:
Post.destroy_all "person_id = 5 AND (category = 'Something' OR category = 'Else')"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 442 442: def delete_all(conditions = nil) 443: sql = "DELETE FROM #{table_name} " 444: add_conditions!(sql, conditions) 445: connection.delete(sql, "#{name} Delete all") 446: end
Destroys the record with the given id by instantiating the object and calling destroy (all the callbacks are the triggered). If an array of ids is provided, all of them are destroyed.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 419 419: def destroy(id) 420: id.is_a?(Array) ? id.each { |id| destroy(id) } : find(id).destroy 421: end
Destroys the objects for all the records that matches the condition by instantiating each object and calling the destroy method. Example:
Person.destroy_all "last_login < '2004-04-04'"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 435 435: def destroy_all(conditions = nil) 436: find(:all, :conditions => conditions).each { |object| object.destroy } 437: 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", :dbfile => "path/to/dbfile" )
Also accepts keys as strings (for parsing from yaml for example):
ActiveRecord::Base.establish_connection( "adapter" => "sqlite", "dbfile" => "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_adapter.rb, line 66 66: def self.establish_connection(spec = nil) 67: case spec 68: when nil 69: raise AdapterNotSpecified unless defined? RAILS_ENV 70: establish_connection(RAILS_ENV) 71: when ConnectionSpecification 72: @@defined_connections[self] = spec 73: when Symbol, String 74: if configuration = configurations[spec.to_s] 75: establish_connection(configuration) 76: else 77: raise AdapterNotSpecified, "#{spec} database is not configured" 78: end 79: else 80: spec = spec.symbolize_keys 81: unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end 82: adapter_method = "#{spec[:adapter]}_connection" 83: unless respond_to?(adapter_method) then raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter" end 84: remove_connection 85: establish_connection(ConnectionSpecification.new(spec, adapter_method)) 86: end 87: end
Returns true if the given id represents the primary key of a record in the database, false otherwise. Example:
Person.exists?(5)
# File vendor/rails/activerecord/lib/active_record/base.rb, line 382 382: def exists?(id) 383: !find(:first, :conditions => ["#{primary_key} = ?", id]).nil? rescue false 384: end
Find operates with three different retreval approaches:
All approaches accepts an option hash as their last parameter. The options are:
Examples for 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 objects the object with ID = 1 Person.find(1, :conditions => "administrator = 1", :order => "created_on DESC")
Examples for 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, :order => "created_on DESC", :offset => 5)
Examples for 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, :offset => 10, :limit => 10) Person.find(:all, :include => [ :account, :friends ])
# File vendor/rails/activerecord/lib/active_record/base.rb, line 336 336: def find(*args) 337: options = extract_options_from_args!(args) 338: 339: case args.first 340: when :first 341: find(:all, options.merge(options[:include] ? { } : { :limit => 1 })).first 342: when :all 343: options[:include] ? find_with_associations(options) : find_by_sql(construct_finder_sql(options)) 344: else 345: return args.first if args.first.kind_of?(Array) && args.first.empty? 346: expects_array = args.first.kind_of?(Array) 347: conditions = " AND #{sanitize_sql(options[:conditions])}" if options[:conditions] 348: 349: ids = args.flatten.compact.uniq 350: case ids.size 351: when 0 352: raise RecordNotFound, "Couldn't find #{name} without an ID#{conditions}" 353: when 1 354: if result = find(:first, options.merge({ :conditions => "#{table_name}.#{primary_key} = #{sanitize(ids.first)}#{conditions}" })) 355: return expects_array ? [ result ] : result 356: else 357: raise RecordNotFound, "Couldn't find #{name} with ID=#{ids.first}#{conditions}" 358: end 359: else 360: # Find multiple ids 361: ids_list = ids.map { |id| sanitize(id) }.join(',') 362: result = find(:all, options.merge({ :conditions => "#{table_name}.#{primary_key} IN (#{ids_list})#{conditions}"})) 363: if result.size == ids.size 364: return result 365: else 366: raise RecordNotFound, "Couldn't find all #{name.pluralize} with IDs (#{ids_list})#{conditions}" 367: end 368: end 369: end 370: end
Works like find(:all), but requires a complete SQL string. Examples:
Post.find_by_sql "SELECT p.*, c.author FROM posts p, comments c WHERE p.id = c.post_id" Post.find_by_sql ["SELECT * FROM posts WHERE author = ? AND created > ?", author_id, start_date]
# File vendor/rails/activerecord/lib/active_record/base.rb, line 375 375: def find_by_sql(sql) 376: connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) } 377: end
Increments the specified counter by one. So DiscussionBoard.increment_counter("post_count", discussion_board_id) would increment the "post_count" counter on the board responding to discussion_board_id. This is used for caching aggregate values, so that they doesn’t need to be computed every time. Especially important for looping over a collection where each element require a number of aggregate values. Like the DiscussionBoard that needs to list both the number of posts and comments.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 475 475: def increment_counter(counter_name, id) 476: update_all "#{counter_name} = #{counter_name} + 1", "#{primary_key} = #{quote(id)}" 477: end
Defines the column name for use with single table inheritance — can be overridden in subclasses.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 570 570: def inheritance_column 571: "type" 572: 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 935 935: def initialize(attributes = nil) 936: @attributes = attributes_from_column_definition 937: @new_record = true 938: ensure_proper_type 939: self.attributes = attributes unless attributes.nil? 940: yield self if block_given? 941: 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 558 558: def primary_key 559: case primary_key_prefix_type 560: when :table_name 561: Inflector.foreign_key(class_name_of_active_record_descendant(self), false) 562: when :table_name_with_underscore 563: Inflector.foreign_key(class_name_of_active_record_descendant(self)) 564: else 565: "id" 566: end 567: end
Remove the connection for this class. This will close the active connection and the defined connection (if they exist). The result can be used as argument for establish_connection, for easy re-establishing of the connection.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb, line 133 133: def self.remove_connection(klass=self) 134: conn = @@defined_connections[klass] 135: @@defined_connections.delete(klass) 136: active_connections[klass] = nil 137: conn.config if conn 138: end
Resets all the cached information about columns, which will cause they to be reloaded on the next request.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 662 662: def reset_column_information 663: @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = nil 664: end
Specifies that the attribute by the name of attr_name should be serialized before saving to the database and unserialized after loading from the database. 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.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 524 524: def serialize(attr_name, class_name = Object) 525: serialized_attributes[attr_name.to_s] = class_name 526: 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 529 529: def serialized_attributes 530: read_inheritable_attribute("attr_serialized") or write_inheritable_attribute("attr_serialized", {}) 531: 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.
Example:
class Project < ActiveRecord::Base set_inheritance_column do original_inheritance_column + "_id" end end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 613 613: def set_inheritance_column( value=nil, &block ) 614: define_attr_method :inheritance_column, value, &block 615: 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.
Example:
class Project < ActiveRecord::Base set_primary_key "sysid" end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 597 597: def set_primary_key( value=nil, &block ) 598: define_attr_method :primary_key, value, &block 599: 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.
Example:
class Project < ActiveRecord::Base set_table_name "project" end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 582 582: def set_table_name( value=nil, &block ) 583: Inflector.add_table_class_relationships( name => value ) if Inflector.tableize( name ) != value 584: define_attr_method :table_name, value, &block 585: end
Silences the logger for the duration of the block.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 706 706: def silence 707: old_logger_level, logger.level = logger.level, Logger::ERROR if logger 708: yield 709: ensure 710: logger.level = old_logger_level if logger 711: end
Guesses the table name (in forced lower-case) based on the name of the class in the inheritance hierarchy descending directly from ActiveRecord. So if the hierarchy looks like: Reply < Message < ActiveRecord, then Message is used to guess the table name from 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 (report a bug if your inflection isn’t covered).
Additionally, the class-level table_name_prefix is prepended to the table_name and the table_name_suffix is appended. So if you have "myapp_" as a prefix, the table name guess for an Account class becomes "myapp_accounts".
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 547 547: def table_name 548: class_name = class_name_of_active_record_descendant(self) 549: if Inflector.class_table_relationship?(class_name) 550: Inflector.tableize(class_name) 551: else 552: "#{table_name_prefix}#{undecorated_table_name(class_name)}#{table_name_suffix}" 553: end 554: end
Finds the record from the passed id, instantly saves it with the passed attributes (if the validation permits it), and returns it. If the save fail under validations, the unsaved object is still returned.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 400 400: def update(id, attributes) 401: if id.is_a?(Array) 402: idx = -1 403: id.collect { |id| idx += 1; update(id, attributes[idx]) } 404: else 405: object = find(id) 406: object.update_attributes(attributes) 407: object 408: end 409: end
Updates all records with the SET-part of an SQL update statement in updates and returns an integer with the number of rows updates. A subset of the records can be selected by specifying conditions. Example:
Billing.update_all "category = 'authorized', approved = 1", "author = 'David'"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 426 426: def update_all(updates, conditions = nil) 427: sql = "UPDATE #{table_name} SET #{sanitize_sql(updates)} " 428: add_conditions!(sql, conditions) 429: connection.update(sql, "#{name} Update") 430: 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 1113 1113: def ==(comparison_object) 1114: comparison_object.equal?(self) or (comparison_object.instance_of?(self.class) and comparison_object.id == id) 1115: end
Returns the value of attribute identified by attr_name after it has been type cast (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 1059 1059: def [](attr_name) 1060: read_attribute(attr_name.to_s) 1061: 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 1065 1065: def []=(attr_name, value) 1066: write_attribute(attr_name.to_s, value) 1067: 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 1103 1103: def attribute_names 1104: @attributes.keys.sort 1105: 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 responds to empty?, most notably Strings).
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1097 1097: def attribute_present?(attribute) 1098: value = read_attribute(attribute) 1099: !value.blank? or value == 0 1100: end
Returns a hash of all the attributes with their names as keys and clones of their objects as values.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1086 1086: def attributes 1087: clone_attributes :read_attribute 1088: 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). 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 in with the attr_accessible macro. Then all the attributes not included in that won’t be allowed to be mass-assigned.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1074 1074: def attributes=(attributes) 1075: return if attributes.nil? 1076: attributes.stringify_keys! 1077: 1078: multi_parameter_attributes = [] 1079: remove_attributes_protected_from_mass_assignment(attributes).each do |k, v| 1080: k.include?("(") ? multi_parameter_attributes << [ k, v ] : send(k + "=", v) 1081: end 1082: assign_multiparameter_attributes(multi_parameter_attributes) 1083: end
Returns a hash of cloned attributes before typecasting and deserialization.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1091 1091: def attributes_before_type_cast 1092: clone_attributes :read_attribute_before_type_cast 1093: end
Returns a clone of the record that hasn’t been assigned an id yet and is treated as a new record.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 991 991: def clone 992: attrs = self.attributes_before_type_cast 993: attrs.delete(self.class.primary_key) 994: self.class.new do |record| 995: record.send :instance_variable_set, '@attributes', attrs 996: end 997: end
Returns the column object for the named attribute.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1108 1108: def column_for_attribute(name) 1109: self.class.columns_hash[name.to_s] 1110: 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/base.rb, line 245 245: def connection 246: self.class.connection 247: end
Initializes the attribute to zero if nil and subtracts one. Only makes sense for number-based attributes. Returns self.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1027 1027: def decrement(attribute) 1028: self[attribute] ||= 0 1029: self[attribute] -= 1 1030: self 1031: end
Decrements the attribute and saves the record.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1034 1034: def decrement!(attribute) 1035: decrement(attribute).update_attribute(attribute, self[attribute]) 1036: 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 978 978: def destroy 979: unless new_record? 980: connection.delete "DELETE FROM \#{self.class.table_name}\nWHERE \#{self.class.primary_key} = \#{quoted_id}\n", "#{self.class.name} Destroy" 981: end 982: 983: freeze 984: end
Delegates to ==
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1118 1118: def eql?(comparison_object) 1119: self == (comparison_object) 1120: end
Just freeze the attributes hash, such that associations are still accessible even on destroyed records.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1138 1138: def freeze 1139: @attributes.freeze 1140: end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1142 1142: def frozen? 1143: @attributes.frozen? 1144: 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 1124 1124: def hash 1125: id.hash 1126: end
Every Active Record class must use "id" as their primary ID. This getter overwrites the native id method, which isn’t being used in this context.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 945 945: def id 946: read_attribute(self.class.primary_key) 947: end
Sets the primary ID.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 961 961: def id=(value) 962: write_attribute(self.class.primary_key, value) 963: end
Initializes the attribute to zero if nil and adds one. Only makes sense for number-based attributes. Returns self.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1015 1015: def increment(attribute) 1016: self[attribute] ||= 0 1017: self[attribute] += 1 1018: self 1019: end
Increments the attribute and saves the record.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1022 1022: def increment!(attribute) 1023: increment(attribute).update_attribute(attribute, self[attribute]) 1024: end
Returns true if this object hasn’t been saved yet — that is, a record for the object doesn’t exist yet.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 966 966: def new_record? 967: @new_record 968: end
Reloads the attributes of this object from the database.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1050 1050: def reload 1051: clear_association_cache 1052: @attributes.update(self.class.find(self.id).instance_variable_get('@attributes')) 1053: self 1054: end
A Person object with a name attribute can ask person.respond_to?("name"), person.respond_to?("name="), and person.respond_to?("name?") which will all return true.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1133 1133: def respond_to?(method, include_priv = false) 1134: self.class.column_methods_hash[method.to_sym] || respond_to_without_attributes?(method, include_priv) 1135: end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 972 972: def save 973: create_or_update 974: end
Turns an attribute that’s currently true into false and vice versa. Returns self.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1039 1039: def toggle(attribute) 1040: self[attribute] = quote(!send("#{attribute}?", column_for_attribute(attribute))) 1041: self 1042: end
Toggles the attribute and saves the record.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1045 1045: def toggle!(attribute) 1046: toggle(attribute).update_attribute(attribute, self[attribute]) 1047: end
Updates a single attribute and saves the record. This is especially useful for boolean flags on existing records. Note: This method is overwritten by the Validation module that’ll make sure that updates made with this method doesn’t get subjected to validation checks. Hence, attributes can be updated even if the full object isn’t valid.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1002 1002: def update_attribute(name, value) 1003: self[name] = value 1004: save 1005: end
Updates all the attributes in from the passed 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 1009 1009: def update_attributes(attributes) 1010: self.attributes = attributes 1011: save 1012: end