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 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, 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 a 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, [ "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 })
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.
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_ 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").
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. 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")
Use the find_or_initialize_by_ finder if you want to return a new record without saving it first. Example:
# No 'Winter' tag exists winter = Tag.find_or_initialize_by_name("Winter") winter.new_record? # true
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 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.
VALID_FIND_OPTIONS | = | [ :conditions, :include, :joins, :limit, :offset, :order, :select, :readonly, :group, :from, :lock ] |
connection= | -> | connection_without_query_cache= |
set_table_name | -> | table_name= |
set_primary_key | -> | primary_key= |
set_inheritance_column | -> | inheritance_column= |
set_sequence_name | -> | sequence_name= |
sanitize_sql | -> | sanitize_conditions |
respond_to? | -> | respond_to_without_attributes? |
For checking respond_to? without searching the attributes (which is faster). |
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 958 958: def ===(object) 959: object.is_a?(self) 960: 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 984 984: def abstract_class? 985: abstract_class == true 986: end
If this macro is used, only those attributes 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 566 566: def attr_accessible(*attributes) 567: write_inheritable_array("attr_accessible", attributes - (accessible_attributes || [])) 568: 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 from being 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 553 553: def attr_protected(*attributes) 554: write_inheritable_array("attr_protected", attributes - (protected_attributes || [])) 555: 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 975 975: def base_class 976: class_of_active_record_descendant(self) 977: 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 matches 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 853 853: def benchmark(title, log_level = Logger::DEBUG, use_silence = true) 854: if logger && logger.level == log_level 855: result = nil 856: seconds = Benchmark.realtime { result = use_silence ? silence { yield } : yield } 857: logger.add(log_level, "#{title} (#{'%.5f' % seconds})") 858: result 859: else 860: yield 861: end 862: end
Clears the cache which maps classes to connections.
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 84 84: def clear_active_connections! 85: clear_cache!(@@active_connections) do |name, conn| 86: conn.disconnect! 87: end 88: end
Clears the cache which maps classes
# File vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb, line 91 91: def clear_reloadable_connections! 92: @@active_connections.each do |name, conn| 93: if conn.requires_reloading? 94: conn.disconnect! 95: @@active_connections.delete(name) 96: end 97: end 98: end
Returns an array of column names as strings.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 775 775: def column_names 776: @column_names ||= columns.map { |column| column.name } 777: end
Returns an array of column objects for the table associated with this class.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 761 761: def columns 762: unless @columns 763: @columns = connection.columns(table_name, "#{name} Columns") 764: @columns.each {|column| column.primary = column.name == primary_key} 765: end 766: @columns 767: 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/connection_specification.rb, line 239 239: def self.connected? 240: active_connections[active_connection_name] ? true : false 241: 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 73 73: def connection 74: if @active_connection_name && (conn = active_connections[@active_connection_name]) 75: conn 76: else 77: # retrieve_connection sets the cache key. 78: conn = retrieve_connection 79: active_connections[@active_connection_name] = conn 80: end 81: end
# File vendor/rails/activerecord/lib/active_record/query_cache.rb, line 50 50: def connection=(spec) 51: if spec.is_a?(ConnectionSpecification) and spec.config[:query_cache] 52: spec = QueryCache.new(self.send(spec.adapter_method, spec.config)) 53: end 54: self.connection_without_query_cache = spec 55: 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 781 781: def content_columns 782: @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column } 783: end
Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part.
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 518 518: def count_by_sql(sql) 519: sql = sanitize_conditions(sql) 520: connection.select_value(sql, "#{name} Count").to_i 521: end
Creates an object, instantly saves it as a record (if the validation permits it), and returns it. If the save fails under validations, the unsaved object is still returned.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 445 445: def create(attributes = nil) 446: if attributes.is_a?(Array) 447: attributes.collect { |attr| create(attr) } 448: else 449: object = new(attributes) 450: scope(:create).each { |att,value| object.send("#{att}=", value) } if scoped?(:create) 451: object.save 452: object 453: end 454: end
Works like increment_counter, but decrements instead.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 533 533: def decrement_counter(counter_name, id) 534: update_all "#{connection.quote_column_name(counter_name)} = #{connection.quote_column_name(counter_name)} - 1", "#{connection.quote_column_name(primary_key)} = #{quote_value(id)}" 535: 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 481 481: def delete(id) 482: delete_all([ "#{connection.quote_column_name(primary_key)} IN (?)", id ]) 483: end
Deletes all the records that match the condition without instantiating the objects first (and hence not calling the destroy method). Example:
Post.delete_all "person_id = 5 AND (category = 'Something' OR category = 'Else')"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 510 510: def delete_all(conditions = nil) 511: sql = "DELETE FROM #{table_name} " 512: add_conditions!(sql, conditions, scope(:find)) 513: connection.delete(sql, "#{name} Delete all") 514: 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 487 487: def destroy(id) 488: id.is_a?(Array) ? id.each { |id| destroy(id) } : find(id).destroy 489: end
Destroys the objects for all the records that match 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 503 503: def destroy_all(conditions = nil) 504: find(:all, :conditions => conditions).each { |object| object.destroy } 505: 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 191 191: def self.establish_connection(spec = nil) 192: case spec 193: when nil 194: raise AdapterNotSpecified unless defined? RAILS_ENV 195: establish_connection(RAILS_ENV) 196: when ConnectionSpecification 197: clear_active_connection_name 198: @active_connection_name = name 199: @@defined_connections[name] = spec 200: when Symbol, String 201: if configuration = configurations[spec.to_s] 202: establish_connection(configuration) 203: else 204: raise AdapterNotSpecified, "#{spec} database is not configured" 205: end 206: else 207: spec = spec.symbolize_keys 208: unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end 209: adapter_method = "#{spec[:adapter]}_connection" 210: unless respond_to?(adapter_method) then raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter" end 211: remove_connection 212: establish_connection(ConnectionSpecification.new(spec, adapter_method)) 213: end 214: end
Returns true if the given id represents the primary key of a record in the database, false otherwise. You can also pass a set of SQL conditions. Example:
Person.exists?(5) Person.exists?('5') Person.exists?(:name => "David") Person.exists?(['name LIKE ?', "%#{query}%"])
# File vendor/rails/activerecord/lib/active_record/base.rb, line 437 437: def exists?(id_or_conditions) 438: !find(:first, :conditions => expand_id_conditions(id_or_conditions)).nil? 439: rescue ActiveRecord::ActiveRecordError 440: false 441: end
Find operates with three different retrieval approaches:
All approaches accept an option hash as their last parameter. The options are:
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 ]) 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 411 411: def find(*args) 412: options = extract_options_from_args!(args) 413: validate_find_options(options) 414: set_readonly_option!(options) 415: 416: case args.first 417: when :first then find_initial(options) 418: when :all then find_every(options) 419: else find_from_ids(args, options) 420: end 421: 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 426 426: def find_by_sql(sql) 427: connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) } 428: 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 don‘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 528 528: def increment_counter(counter_name, id) 529: update_all "#{connection.quote_column_name(counter_name)} = #{connection.quote_column_name(counter_name)} + 1", "#{connection.quote_column_name(primary_key)} = #{quote_value(id)}" 530: 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 656 656: def inheritance_column 657: @inheritance_column ||= "type".freeze 658: 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 1504 1504: def initialize(attributes = nil) 1505: @attributes = attributes_from_column_definition 1506: @new_record = true 1507: ensure_proper_type 1508: self.attributes = attributes unless attributes.nil? 1509: yield self if block_given? 1510: 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 638 638: def primary_key 639: reset_primary_key 640: 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/connection_specification.rb, line 247 247: def self.remove_connection(klass=self) 248: spec = @@defined_connections[klass.name] 249: konn = active_connections[klass.name] 250: @@defined_connections.delete_if { |key, value| value == spec } 251: active_connections.delete_if { |key, value| value == konn } 252: konn.disconnect! if konn 253: spec.config if spec 254: end
# File vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb, line 46 46: def self.require_mysql 47: # Include the MySQL driver if one hasn't already been loaded 48: unless defined? Mysql 49: begin 50: require_library_or_gem 'mysql' 51: rescue LoadError => cannot_require_mysql 52: # Use the bundled Ruby/MySQL driver if no driver is already in place 53: begin 54: require 'active_record/vendor/mysql' 55: rescue LoadError 56: raise cannot_require_mysql 57: end 58: end 59: end 60: 61: # Define Mysql::Result.all_hashes 62: MysqlCompat.define_all_hashes_method! 63: end
Resets all the cached information about columns, which will cause them to be reloaded on the next request.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 805 805: def reset_column_information 806: read_methods.each { |name| undef_method(name) } 807: @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @read_methods = @inheritance_column = nil 808: 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 nil. Otherwise, SerializationTypeMismatch will be raised.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 579 579: def serialize(attr_name, class_name = Object) 580: serialized_attributes[attr_name.to_s] = class_name 581: 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 584 584: def serialized_attributes 585: read_inheritable_attribute("attr_serialized") or write_inheritable_attribute("attr_serialized", {}) 586: 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 710 710: def set_inheritance_column(value = nil, &block) 711: define_attr_method :inheritance_column, value, &block 712: 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 694 694: def set_primary_key(value = nil, &block) 695: define_attr_method :primary_key, value, &block 696: 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.
Example:
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 731 731: def set_sequence_name(value = nil, &block) 732: define_attr_method :sequence_name, value, &block 733: 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 680 680: def set_table_name(value = nil, &block) 681: define_attr_method :table_name, value, &block 682: end
Silences the logger for the duration of the block.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 865 865: def silence 866: old_logger_level, logger.level = logger.level, Logger::ERROR if logger 867: yield 868: ensure 869: logger.level = old_logger_level if logger 870: end
Indicates whether the table associated with this class exists
# File vendor/rails/activerecord/lib/active_record/base.rb, line 745 745: def table_exists? 746: if connection.respond_to?(:tables) 747: connection.tables.include? table_name 748: else 749: # if the connection adapter hasn't implemented tables, there are two crude tests that can be 750: # used - see if getting column info raises an error, or if the number of columns returned is zero 751: begin 752: reset_column_information 753: columns.size > 0 754: rescue ActiveRecord::StatementInvalid 755: false 756: end 757: end 758: 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).
Nested classes are given table names prefixed by the singular form of the parent‘s table name. Example:
file class table_name invoice.rb Invoice invoices invoice/lineitem.rb Invoice::Lineitem invoice_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 611 611: def table_name 612: reset_table_name 613: 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 fails under validations, the unsaved object is still returned.
The arguments may also be given as arrays in which case the update method is called for each pair of id and attributes and an array of objects is returned.
Example of updating one record:
Person.update(15, {:user_name => 'Samuel', :group => 'expert'})
Example of 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 468 468: def update(id, attributes) 469: if id.is_a?(Array) 470: idx = -1 471: id.collect { |id| idx += 1; update(id, attributes[idx]) } 472: else 473: object = find(id) 474: object.update_attributes(attributes) 475: object 476: end 477: end
Updates all records with the SET-part of an SQL update statement in updates and returns an integer with the number of rows updated. 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 494 494: def update_all(updates, conditions = nil) 495: sql = "UPDATE #{table_name} SET #{sanitize_sql(updates)} " 496: add_conditions!(sql, conditions, scope(:find)) 497: connection.update(sql, "#{name} Update") 498: end
Works like with_scope, but discards any nested properties.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 953 953: def with_exclusive_scope(method_scoping = {}, &block) 954: with_scope(method_scoping, :overwrite, &block) 955: 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.
Article.with_scope(:find => { :conditions => "blog_id = 1" }, :create => { :blog_id => 1 }) do Article.find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1 a = Article.create(1) a.blog_id # => 1 end
In nested scopings, all previous parameters are overwritten by inner rule except :conditions in :find, that are merged as hash.
Article.with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }, :create => { :blog_id => 1 }) do Article.with_scope(:find => { :limit => 10}) Article.find(:all) # => SELECT * from articles WHERE blog_id = 1 LIMIT 10 end Article.with_scope(:find => { :conditions => "author_id = 3" }) Article.find(:all) # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1 end end
You can ignore any previous scopings by using with_exclusive_scope method.
Article.with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }) do Article.with_exclusive_scope(:find => { :limit => 10 }) Article.find(:all) # => SELECT * from articles LIMIT 10 end end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 901 901: def with_scope(method_scoping = {}, action = :merge, &block) 902: method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping) 903: 904: # Dup first and second level of hash (method and params). 905: method_scoping = method_scoping.inject({}) do |hash, (method, params)| 906: hash[method] = (params == true) ? params : params.dup 907: hash 908: end 909: 910: method_scoping.assert_valid_keys([ :find, :create ]) 911: 912: if f = method_scoping[:find] 913: f.assert_valid_keys([ :conditions, :joins, :select, :include, :from, :offset, :limit, :order, :readonly, :lock ]) 914: f[:readonly] = true if !f[:joins].blank? && !f.has_key?(:readonly) 915: end 916: 917: # Merge scopings 918: if action == :merge && current_scoped_methods 919: method_scoping = current_scoped_methods.inject(method_scoping) do |hash, (method, params)| 920: case hash[method] 921: when Hash 922: if method == :find 923: (hash[method].keys + params.keys).uniq.each do |key| 924: merge = hash[method][key] && params[key] # merge if both scopes have the same key 925: if key == :conditions && merge 926: hash[method][key] = [params[key], hash[method][key]].collect{ |sql| "( %s )" % sanitize_sql(sql) }.join(" AND ") 927: elsif key == :include && merge 928: hash[method][key] = merge_includes(hash[method][key], params[key]).uniq 929: else 930: hash[method][key] = hash[method][key] || params[key] 931: end 932: end 933: else 934: hash[method] = params.merge(hash[method]) 935: end 936: else 937: hash[method] = params 938: end 939: hash 940: end 941: end 942: 943: self.scoped_methods << method_scoping 944: 945: begin 946: yield 947: ensure 948: self.scoped_methods.pop 949: end 950: end
Returns the class descending directly from ActiveRecord in the inheritance hierarchy.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1368 1368: def class_of_active_record_descendant(klass) 1369: if klass.superclass == Base || klass.superclass.abstract_class? 1370: klass 1371: elsif klass.superclass.nil? 1372: raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord" 1373: else 1374: class_of_active_record_descendant(klass.superclass) 1375: end 1376: end
Returns the class type of the record using the current module as a prefix. So descendents of MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1358 1358: def compute_type(type_name) 1359: modularized_name = type_name_with_module(type_name) 1360: begin 1361: class_eval(modularized_name, __FILE__, __LINE__) 1362: rescue NameError 1363: class_eval(type_name, __FILE__, __LINE__) 1364: end 1365: end
Accepts an array, hash, or string of sql conditions and sanitizes them into a valid SQL fragment.
["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 1388 1388: def sanitize_sql(condition) 1389: case condition 1390: when Array; sanitize_sql_array(condition) 1391: when Hash; sanitize_sql_hash(condition) 1392: else condition 1393: end 1394: 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 1414 1414: def sanitize_sql_array(ary) 1415: statement, *values = ary 1416: if values.first.is_a?(Hash) and statement =~ /:\w+/ 1417: replace_named_bind_variables(statement, values.first) 1418: elsif statement.include?('?') 1419: replace_bind_variables(statement, values) 1420: else 1421: statement % values.collect { |value| connection.quote_string(value.to_s) } 1422: end 1423: end
Sanitizes a hash of attribute/value pairs into SQL conditions.
{ :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"
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1403 1403: def sanitize_sql_hash(attrs) 1404: conditions = attrs.map do |attr, value| 1405: "#{table_name}.#{connection.quote_column_name(attr)} #{attribute_condition(value)}" 1406: end.join(' AND ') 1407: 1408: replace_bind_variables(conditions, expand_range_bind_variables(attrs.values)) 1409: 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 1732 1732: def ==(comparison_object) 1733: comparison_object.equal?(self) || 1734: (comparison_object.instance_of?(self.class) && 1735: comparison_object.id == id && 1736: !comparison_object.new_record?) 1737: 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 1654 1654: def [](attr_name) 1655: read_attribute(attr_name) 1656: 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 1660 1660: def []=(attr_name, value) 1661: write_attribute(attr_name, value) 1662: 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 1722 1722: def attribute_names 1723: @attributes.keys.sort 1724: 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 1711 1711: def attribute_present?(attribute) 1712: value = read_attribute(attribute) 1713: !value.blank? or value == 0 1714: 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 1684 1684: def attributes(options = nil) 1685: attributes = clone_attributes :read_attribute 1686: 1687: if options.nil? 1688: attributes 1689: else 1690: if except = options[:except] 1691: except = Array(except).collect { |attribute| attribute.to_s } 1692: except.each { |attribute_name| attributes.delete(attribute_name) } 1693: attributes 1694: elsif only = options[:only] 1695: only = Array(only).collect { |attribute| attribute.to_s } 1696: attributes.delete_if { |key, value| !only.include?(key) } 1697: attributes 1698: else 1699: raise ArgumentError, "Options does not specify :except or :only (#{options.keys.inspect})" 1700: end 1701: end 1702: 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 1669 1669: def attributes=(new_attributes) 1670: return if new_attributes.nil? 1671: attributes = new_attributes.dup 1672: attributes.stringify_keys! 1673: 1674: multi_parameter_attributes = [] 1675: remove_attributes_protected_from_mass_assignment(attributes).each do |k, v| 1676: k.include?("(") ? multi_parameter_attributes << [ k, v ] : send(k + "=", v) 1677: end 1678: 1679: assign_multiparameter_attributes(multi_parameter_attributes) 1680: end
Returns a hash of cloned attributes before typecasting and deserialization.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1705 1705: def attributes_before_type_cast 1706: clone_attributes :read_attribute_before_type_cast 1707: 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 1576 1576: def clone 1577: attrs = self.attributes_before_type_cast 1578: attrs.delete(self.class.primary_key) 1579: self.class.new do |record| 1580: record.send :instance_variable_set, '@attributes', attrs 1581: end 1582: end
Returns the column object for the named attribute.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1727 1727: def column_for_attribute(name) 1728: self.class.columns_hash[name.to_s] 1729: 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 160 160: def connection 161: self.class.connection 162: 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 1618 1618: def decrement(attribute) 1619: self[attribute] ||= 0 1620: self[attribute] -= 1 1621: self 1622: end
Decrements the attribute and saves the record.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1625 1625: def decrement!(attribute) 1626: decrement(attribute).update_attribute(attribute, self[attribute]) 1627: 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 1559 1559: def destroy 1560: unless new_record? 1561: connection.delete "DELETE FROM \#{self.class.table_name}\nWHERE \#{connection.quote_column_name(self.class.primary_key)} = \#{quoted_id}\n", "#{self.class.name} Destroy" 1562: end 1563: 1564: freeze 1565: end
Delegates to ==
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1740 1740: def eql?(comparison_object) 1741: self == (comparison_object) 1742: 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 1772 1772: def freeze 1773: @attributes.freeze; self 1774: end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1776 1776: def frozen? 1777: @attributes.frozen? 1778: end
Returns true if the given attribute is in the attributes hash
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1717 1717: def has_attribute?(attr_name) 1718: @attributes.has_key?(attr_name.to_s) 1719: 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 1746 1746: def hash 1747: id.hash 1748: 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 1514 1514: def id 1515: attr_name = self.class.primary_key 1516: column = column_for_attribute(attr_name) 1517: define_read_method(:id, attr_name, column) if self.class.generate_read_methods 1518: read_attribute(attr_name) 1519: end
Sets the primary ID.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1536 1536: def id=(value) 1537: write_attribute(self.class.primary_key, value) 1538: 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 1606 1606: def increment(attribute) 1607: self[attribute] ||= 0 1608: self[attribute] += 1 1609: self 1610: end
Increments the attribute and saves the record.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1613 1613: def increment!(attribute) 1614: increment(attribute).update_attribute(attribute, self[attribute]) 1615: 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 1541 1541: def new_record? 1542: @new_record 1543: end
Records loaded through joins with piggy-back attributes will be marked as read only as they cannot be saved and return true to this query.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1781 1781: def readonly? 1782: @readonly == true 1783: 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 1644 1644: def reload(options = nil) 1645: clear_aggregation_cache 1646: clear_association_cache 1647: @attributes.update(self.class.find(self.id, options).instance_variable_get('@attributes')) 1648: self 1649: 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 1755 1755: def respond_to?(method, include_priv = false) 1756: if @attributes.nil? 1757: return super 1758: elsif attr_name = self.class.column_methods_hash[method.to_sym] 1759: return true if @attributes.include?(attr_name) || attr_name == self.class.primary_key 1760: return false if self.class.read_methods.include?(attr_name) 1761: elsif @attributes.include?(method_name = method.to_s) 1762: return true 1763: elsif md = self.class.match_attribute_method?(method.to_s) 1764: return true if @attributes.include?(md.pre_match) 1765: end 1766: # super must be called at the end of the method, because the inherited respond_to? 1767: # would return true for generated readers, even if the attribute wasn't present 1768: super 1769: end
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1547 1547: def save 1548: create_or_update 1549: end
Enables Active Record objects to be used as URL parameters in Action Pack automatically.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1522 1522: def to_param 1523: # We can't use alias_method here, because method 'id' optimizes itself on the fly. 1524: (id = self.id) ? id.to_s : nil # Be sure to stringify the id for routes 1525: 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 1630 1630: def toggle(attribute) 1631: self[attribute] = !send("#{attribute}?") 1632: self 1633: end
Toggles the attribute and saves the record.
# File vendor/rails/activerecord/lib/active_record/base.rb, line 1636 1636: def toggle!(attribute) 1637: toggle(attribute).update_attribute(attribute, self[attribute]) 1638: 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 1587 1587: def update_attribute(name, value) 1588: send(name.to_s + '=', value) 1589: save 1590: 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 1594 1594: def update_attributes(attributes) 1595: self.attributes = attributes 1596: save 1597: 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 1600 1600: def update_attributes!(attributes) 1601: self.attributes = attributes 1602: save! 1603: end