Class: ActiveRecord::Base

### Home Classes Methods

### In Files

- lib/active_record/base.rb
- lib/active_record/connection_adapters/abstract/connection_specification.rb
- lib/active_record/connection_adapters/mysql_adapter.rb
- lib/active_record/connection_adapters/postgresql_adapter.rb
- lib/active_record/connection_adapters/sqlite3_adapter.rb

### Parent

Object

### Methods

- ::===
- ::abstract_class?
- ::aggregate_mapping
- ::arel_engine
- ::arel_table
- ::attr_readonly
- ::attribute_method?
- ::base_class
- ::class_of_active_record_descendant
- ::colorize_logging
- ::colorize_logging=
- ::column_names
- ::columns
- ::columns_hash
- ::compute_type
- ::configurations
- ::connected?
- ::connection
- ::connection_handler
- ::connection_pool
- ::content_columns
- ::count_by_sql
- ::create
- ::default_scope
- ::default_timezone
- ::descends_from_active_record?
- ::establish_connection
- ::expand_hash_conditions_for_aggregates
- ::find_by_sql
- ::inheritance_column
- ::inheritance_column=
- ::inspect
- ::logger
- ::new
- ::pluralize_table_names
- ::primary_key_prefix_type
- ::quoted_table_name
- ::readonly_attributes
- ::remove_connection
- ::reset_column_information
- ::respond_to?
- ::retrieve_connection
- ::sanitize_conditions
- ::sanitize_sql
- ::sanitize_sql_array
- ::sanitize_sql_for_assignment
- ::sanitize_sql_for_conditions
- ::sanitize_sql_hash
- ::sanitize_sql_hash_for_assignment
- ::sanitize_sql_hash_for_conditions
- ::schema_format
- ::sequence_name=
- ::serialize
- ::serialized_attributes
- ::set_inheritance_column
- ::set_sequence_name
- ::set_table_name
- ::sti_name
- ::subclasses
- ::table_exists?
- ::table_name
- ::table_name=
- ::table_name_prefix
- ::table_name_suffix
- ::timestamped_migrations
- ::with_exclusive_scope
- ::with_scope
- #==
- #[]
- #[]=
- #attribute_for_inspect
- #attribute_names
- #attribute_present?
- #attributes
- #attributes=
- #cache_key
- #clone_attribute_value
- #clone_attributes
- #column_for_attribute
- #connection
- #dup
- #eql?
- #freeze
- #frozen?
- #has_attribute?
- #hash
- #init_with
- #initialize_copy
- #inspect
- #readonly!
- #readonly?
- #to_param

### Files

- README.rdoc

### Class/Module Index

Quicksearch

- ActiveRecord
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- ActiveRecord::WrappedDatabaseException
- <
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No matching classes.

# ActiveRecord::Base

# Active Record

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/activerecord/README_rdoc.html for more insight.

## Creation

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

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)
        where("user_name = '#{user_name}' AND password = '#{password}'").first
      end

      def self.authenticate_safely(user_name, password)
        where("user_name = ? AND password = ?", user_name, password).first
      end

      def self.authenticate_safely_simply(user_name, password)
        where(:user_name => user_name, :password => password).first
      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.where(
      "id = :id AND name = :name AND division = :division AND created_at > :accounting_date",
      { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' }
    ).first

Similarly, a simple hash without a statement will generate conditions based on equality with the SQL AND operator. For instance:

    Student.where(:first_name => "Harvey", :status => 1)
    Student.where(params[:student])

A range may be used in the hash to use the SQL BETWEEN operator:

    Student.where(:grade => 9..12)

An array may be used in the hash to use the SQL IN operator:

    Student.where(:grade => [9,11,12])

When joining tables, nested hashes or keys written in the form ‘table_name.column_name’ can be used to qualify the table name of a particular condition. For instance:

    Student.joins(:schools).where(:schools => { :type => 'public' })
    Student.joins(:schools).where('schools.type' => 'public' )

## Overwriting default accessors

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.

    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)`.

## Attribute query methods

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

## Accessing attributes before they have been typecasted

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

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_` and thus produces finders like `Person.find_by_user_name`, `Person.find_all_by_last_name`, and `Payment.find_by_transaction_id`. Instead of writing `Person.where(:user_name => user_name).first`, you just do `Person.find_by_user_name(user_name)`. And instead of writing `Person.where(:last_name => last_name).all`, 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”.

    Person.where(:user_name => user_name, :password => password).first
    Person.find_by_user_name_and_password #with dynamic finder

    Person.where(:user_name => user_name, :password => password, :gender => 'male').first
    Payment.find_by_user_name_and_password_and_gender

It’s even possible to call these dynamic finder methods on relations and named scopes.

    Payment.order("created_on").find_all_by_amount(50)
    Payment.pending.find_last_by_amount(100)

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.

    # 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.

    # 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.

    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.

Just like `find_by_*`, you can also use `scoped_by_*` to retrieve data. The good thing about using this feature is that the very first time result is returned using `method_missing` technique but after that the method is declared on the class. Henceforth `method_missing` will not be hit.

    User.scoped_by_user_name('David')

## Saving arrays, hashes, and other non-mappable objects in text columns

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.

    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.

    class User < ActiveRecord::Base
      serialize :preferences, Hash
    end

    user = User.create(:preferences => %w( one two three ))
    User.find(user.id).preferences    # raises SerializationTypeMismatch

## Single table inheritance

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.where(:name => '37signals').first` 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

## Connection to multiple databases in different models

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.

## Exceptions

- ActiveRecordError - Generic error class and superclass of all other errors raised by Active Record.

- AdapterNotSpecified - The configuration hash used in `establish_connection` didn't include an `:adapter` key.

- AdapterNotFound - The `:adapter` key used in `establish_connection` specified a non-existent adapter (or a bad spelling of an existing one).

- AssociationTypeMismatch - The object assigned to the association wasn't of the type specified in the association definition.

- SerializationTypeMismatch - The serialized object wasn't of the class specified as the second parameter.

- ConnectionNotEstablished+ - No connection has been established. Use `establish_connection` before querying.

- RecordNotFound - No record responded to the `find` method. Either the row with the given ID doesn't exist or the row didn't meet the additional restrictions. Some `find` calls do not raise this exception to signal nothing was found, please check its documentation for further details.

- StatementInvalid - The database server rejected the SQL statement. The precise error is added in the message.

- MultiparameterAssignmentErrors - Collection of errors that occurred during a mass assignment using the `attributes=` method. The `errors` property of this exception contains an array of AttributeAssignmentError objects that should be inspected to determine which attributes triggered the errors.

- AttributeAssignmentError - An error occurred while doing a mass assignment through the `attributes=` method. You can inspect the `attribute` property of the exception object to determine which attribute triggered the error.

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.

### Attributes

abstract_class[RW]

Set this to true if this is an abstract class (see `abstract_class?`).

### Public Class Methods

===(object) click to toggle source

Overwrite the default class equality method to provide support for association proxies.

    # File lib/active_record/base.rb, line 813
    def ===(object)
      object.is_a?(self)
    end

abstract_class?() click to toggle source

Returns whether this class is an abstract class or not.

    # File lib/active_record/base.rb, line 831
    def abstract_class?
      defined?(@abstract_class) && @abstract_class == true
    end

arel_engine() click to toggle source

    # File lib/active_record/base.rb, line 853
    def arel_engine
      @arel_engine ||= begin
        if self == ActiveRecord::Base
          Arel::Table.engine
        else
          connection_handler.connection_pools[name] ? self : superclass.arel_engine
        end
      end
    end

arel_table() click to toggle source

    # File lib/active_record/base.rb, line 849
    def arel_table
      @arel_table ||= Arel::Table.new(table_name, arel_engine)
    end

attr_readonly(*attributes) click to toggle source

Attributes listed as readonly will be used to create a new record but update operations will ignore these fields.

    # File lib/active_record/base.rb, line 521
    def attr_readonly(*attributes)
      write_inheritable_attribute(:attr_readonly, Set.new(attributes.map { |a| a.to_s }) + (readonly_attributes || []))
    end

attribute_method?(attribute) click to toggle source

    # File lib/active_record/base.rb, line 751
    def attribute_method?(attribute)
      super || (table_exists? && column_names.include?(attribute.to_s.sub(/=$/, '')))
    end

base_class() click to toggle source

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.

If B < A and C < B and if A is an abstract_class then both B.base_class and C.base_class would return B as the answer since A is an abstract_class.

    # File lib/active_record/base.rb, line 823
    def base_class
      class_of_active_record_descendant(self)
    end

colorize_logging(*args) click to toggle source

    # File lib/active_record/base.rb, line 432
    def colorize_logging(*args)
      ActiveSupport::Deprecation.warn "ActiveRecord::Base.colorize_logging and " <<
        "config.active_record.colorize_logging are deprecated. Please use " <<
        "Rails::LogSubscriber.colorize_logging or config.colorize_logging instead", caller
    end

Also aliased as: colorize_logging=
colorize_logging=(*args) click to toggle source
Alias for: colorize_logging
column_names() click to toggle source

Returns an array of column names as strings.

    # File lib/active_record/base.rb, line 691
    def column_names
      @column_names ||= columns.map { |column| column.name }
    end

columns() click to toggle source

Returns an array of column objects for the table associated with this class.

    # File lib/active_record/base.rb, line 677
    def columns
      unless defined?(@columns) && @columns
        @columns = connection.columns(table_name, "#{name} Columns")
        @columns.each { |column| column.primary = column.name == primary_key }
      end
      @columns
    end

columns_hash() click to toggle source

Returns a hash of column objects for the table associated with this class.

    # File lib/active_record/base.rb, line 686
    def columns_hash
      @columns_hash ||= Hash[columns.map { |column| [column.name, column] }]
    end

configurations click to toggle source

Contains the database configuration - as is typically stored in config/database.yml - as a Hash.

For example, the following database.yml…

    development:
      adapter: sqlite3
      database: db/development.sqlite3

    production:
      adapter: sqlite3
      database: db/production.sqlite3

…would result in ActiveRecord::Base.configurations to look like this:

    {
       'development' => {
          'adapter'  => 'sqlite3',
          'database' => 'db/development.sqlite3'
       },
       'production' => {
          'adapter'  => 'sqlite3',
          'database' => 'db/production.sqlite3'
       }
    }

    # File lib/active_record/base.rb, line 358
    cattr_accessor :configurations, :instance_writer => false

connected?() click to toggle source

Returns true if Active Record is connected.

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 101
    def connected?
      connection_handler.connected?(self)
    end

connection() click to toggle source

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 lib/active_record/connection_adapters/abstract/connection_specification.rb, line 88
    def connection
      retrieve_connection
    end

connection_handler click to toggle source

The connection handler

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 13
    class_attribute :connection_handler, :instance_writer => false

connection_pool() click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 92
    def connection_pool
      connection_handler.retrieve_connection_pool(self)
    end

content_columns() click to toggle source

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 lib/active_record/base.rb, line 697
    def content_columns
      @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
    end

count_by_sql(sql) click to toggle source

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.

#### Parameters

- `sql` - An SQL statement which should return a count query from the database, see the example below.

#### Examples

    Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"

    # File lib/active_record/base.rb, line 514
    def count_by_sql(sql)
      sql = sanitize_conditions(sql)
      connection.select_value(sql, "#{name} Count").to_i
    end

create(attributes = nil, &block) click to toggle source

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.

#### Examples

    # 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 lib/active_record/base.rb, line 492
    def create(attributes = nil, &block)
      if attributes.is_a?(Array)
        attributes.collect { |attr| create(attr, &block) }
      else
        object = new(attributes)
        yield(object) if block_given?
        object.save
        object
      end
    end

default_timezone click to toggle source

Determines whether to use Time.local (using :local) or Time.utc (using :utc) when pulling dates and times from the database. This is set to :local by default.

    # File lib/active_record/base.rb, line 403
    cattr_accessor :default_timezone, :instance_writer => false

descends_from_active_record?() click to toggle source

True if this isn’t a concrete subclass needing a STI type condition.

    # File lib/active_record/base.rb, line 776
    def descends_from_active_record?
      if superclass.abstract_class?
        superclass.descends_from_active_record?
      else
        superclass == Base || !columns_hash.include?(inheritance_column)
      end
    end

establish_connection(spec = nil) click to toggle source

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 lib/active_record/connection_adapters/abstract/connection_specification.rb, line 51
    def self.establish_connection(spec = nil)
      case spec
        when nil
          raise AdapterNotSpecified unless defined?(Rails.env)
          establish_connection(Rails.env)
        when ConnectionSpecification
          self.connection_handler.establish_connection(name, spec)
        when Symbol, String
          if configuration = configurations[spec.to_s]
            establish_connection(configuration)
          else
            raise AdapterNotSpecified, "#{spec} database is not configured"
          end
        else
          spec = spec.symbolize_keys
          unless spec.key?(:adapter) then raise AdapterNotSpecified, "database configuration does not specify adapter" end

          begin
            require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
          rescue LoadError => e
            raise "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{e})"
          end

          adapter_method = "#{spec[:adapter]}_connection"
          if !respond_to?(adapter_method)
            raise AdapterNotFound, "database configuration specifies nonexistent #{spec[:adapter]} adapter"
          end

          remove_connection
          establish_connection(ConnectionSpecification.new(spec, adapter_method))
      end
    end

find_by_sql(sql) click to toggle source

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.

#### Examples

    # 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 lib/active_record/base.rb, line 466
    def find_by_sql(sql)
      connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) }
    end

inheritance_column() click to toggle source

Defines the column name for use with single table inheritance. Use `set_inheritance_column` to set a different value.

    # File lib/active_record/base.rb, line 610
    def inheritance_column
      @inheritance_column ||= "type"
    end

inheritance_column=(value = nil, &block) click to toggle source
Alias for: set_inheritance_column
inspect() click to toggle source

Returns a string like ‘Post id:integer, title:string, body:text’

    # File lib/active_record/base.rb, line 790
    def inspect
      if self == Base
        super
      elsif abstract_class?
        "#{super}(abstract)"
      elsif table_exists?
        attr_list = columns.map { |c| "#{c.name}: #{c.type}" } * ', '
        "#{super}(#{attr_list})"
      else
        "#{super}(Table doesn't exist)"
      end
    end

logger click to toggle source

Accepts a logger conforming to the interface of Log4r or the default Ruby 1.8+ Logger class, which is then passed on to any new database connections made and which can be retrieved on both a class and instance level by calling `logger`.

    # File lib/active_record/base.rb, line 317
    cattr_accessor :logger, :instance_writer => false

new(attributes = nil) click to toggle source

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 lib/active_record/base.rb, line 1393
    def initialize(attributes = nil)
      @attributes = attributes_from_column_definition
      @attributes_cache = {}
      @new_record = true
      @readonly = false
      @destroyed = false
      @marked_for_destruction = false
      @previously_changed = {}
      @changed_attributes = {}

      ensure_proper_type

      populate_with_current_scope_attributes
      self.attributes = attributes unless attributes.nil?

      result = yield self if block_given?
      _run_initialize_callbacks
      result
    end

pluralize_table_names click to toggle source

Indicates whether table names should be the pluralized versions of the corresponding class names. If true, the default table name for a Product class will be `products`. If false, it would just be `product`. See table_name for the full rules on table/class naming. This is true, by default.

    # File lib/active_record/base.rb, line 396
    cattr_accessor :pluralize_table_names, :instance_writer => false

primary_key_prefix_type click to toggle source

Accessor for the prefix type that will be prepended to every primary key column name. The options are :table_name and :table_name_with_underscore. If the first is specified, the Product class will look for “productid” instead of “id” as the primary column. If the latter is specified, the Product class will look for “product_id” instead of “id”. Remember that this is a global setting for all Active Records.

    # File lib/active_record/base.rb, line 368
    cattr_accessor :primary_key_prefix_type, :instance_writer => false

quoted_table_name() click to toggle source

Returns a quoted version of the table name, used to construct SQL statements.

    # File lib/active_record/base.rb, line 595
    def quoted_table_name
      @quoted_table_name ||= connection.quote_table_name(table_name)
    end

readonly_attributes() click to toggle source

Returns an array of all the attributes that have been specified as readonly.

    # File lib/active_record/base.rb, line 526
    def readonly_attributes
      read_inheritable_attribute(:attr_readonly) || []
    end

remove_connection(klass = self) click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 105
    def remove_connection(klass = self)
      connection_handler.remove_connection(klass)
    end

reset_column_information() click to toggle source

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 lib/active_record/base.rb, line 741
    def reset_column_information
      undefine_attribute_methods
      @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @inheritance_column = nil
      @arel_engine = @relation = @arel_table = nil
    end

respond_to?(method_id, include_private = false) click to toggle source

    # File lib/active_record/base.rb, line 835
    def respond_to?(method_id, include_private = false)
      if match = DynamicFinderMatch.match(method_id)
        return true if all_attributes_exists?(match.attribute_names)
      elsif match = DynamicScopeMatch.match(method_id)
        return true if all_attributes_exists?(match.attribute_names)
      end

      super
    end

retrieve_connection() click to toggle source

    # File lib/active_record/connection_adapters/abstract/connection_specification.rb, line 96
    def retrieve_connection
      connection_handler.retrieve_connection(self)
    end

schema_format click to toggle source

Specifies the format to use when dumping the database schema with Rails’ Rakefile. If :sql, the schema is dumped as (potentially database- specific) SQL statements. If :ruby, the schema is dumped as an ActiveRecord::Schema file which can be loaded into any database that supports migrations. Use :ruby if you want to have different database adapters for, e.g., your development and test environments.

    # File lib/active_record/base.rb, line 414
    cattr_accessor :schema_format , :instance_writer => false

sequence_name=(value = nil, &block) click to toggle source
Alias for: set_sequence_name
serialize(attr_name, class_name = Object) click to toggle source

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.

#### Parameters

- `attr_name` - The field name that should be serialized.

- `class_name` - Optional, class name that the object type should be equal to.

#### Example

    # Serialize a preferences attribute
    class User
      serialize :preferences
    end

    # File lib/active_record/base.rb, line 545
    def serialize(attr_name, class_name = Object)
      serialized_attributes[attr_name.to_s] = class_name
    end

serialized_attributes() click to toggle source

Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.

    # File lib/active_record/base.rb, line 551
    def serialized_attributes
      read_inheritable_attribute(:attr_serialized) or write_inheritable_attribute(:attr_serialized, {})
    end

set_inheritance_column(value = nil, &block) click to toggle source

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 lib/active_record/base.rb, line 647
    def set_inheritance_column(value = nil, &block)
      define_attr_method :inheritance_column, value, &block
    end

Also aliased as: inheritance_column=
set_sequence_name(value = nil, &block) click to toggle source

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 lib/active_record/base.rb, line 666
    def set_sequence_name(value = nil, &block)
      define_attr_method :sequence_name, value, &block
    end

Also aliased as: sequence_name=
set_table_name(value = nil, &block) click to toggle source

Sets the table name. If the value is nil or false then the value returned by the given block is used.

    class Project < ActiveRecord::Base
      set_table_name "project"
    end

    # File lib/active_record/base.rb, line 632
    def set_table_name(value = nil, &block)
      @quoted_table_name = nil
      define_attr_method :table_name, value, &block
    end

Also aliased as: table_name=
sti_name() click to toggle source

    # File lib/active_record/base.rb, line 845
    def sti_name
      store_full_sti_class ? name : name.demodulize
    end

subclasses() click to toggle source

    # File lib/active_record/base.rb, line 324
    def subclasses
      descendants
    end

table_exists?() click to toggle source

Indicates whether the table associated with this class exists

    # File lib/active_record/base.rb, line 672
    def table_exists?
      connection.table_exists?(table_name)
    end

table_name() click to toggle source

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.

#### Examples

    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 lib/active_record/base.rb, line 590
    def table_name
      reset_table_name
    end

table_name=(value = nil, &block) click to toggle source
Alias for: set_table_name
table_name_prefix click to toggle source

Accessor for the name of the prefix string to prepend to every table name. So if set to “basecamp_”, all table names will be named like “basecamp_projects”, “basecamp_people”, etc. This is a convenient way of creating a namespace for tables in a shared database. By default, the prefix is the empty string.

If you are organising your models within modules you can add a prefix to the models within a namespace by defining a singleton method in the parent module called table_name_prefix which returns your chosen prefix.

    # File lib/active_record/base.rb, line 381
    class_attribute :table_name_prefix, :instance_writer => false

table_name_suffix click to toggle source

Works like `table_name_prefix`, but appends instead of prepends (set to “_basecamp” gives “projects_basecamp”, “people_basecamp”). By default, the suffix is the empty string.

    # File lib/active_record/base.rb, line 388
    class_attribute :table_name_suffix, :instance_writer => false

timestamped_migrations click to toggle source

Specify whether or not to use timestamps for migration versions

    # File lib/active_record/base.rb, line 420
    cattr_accessor :timestamped_migrations , :instance_writer => false

### Protected Class Methods

aggregate_mapping(reflection) click to toggle source

    # File lib/active_record/base.rb, line 1242
    def aggregate_mapping(reflection)
      mapping = reflection.options[:mapping] || [reflection.name, reflection.name]
      mapping.first.is_a?(Array) ? mapping : [mapping]
    end

class_of_active_record_descendant(klass) click to toggle source

Returns the class descending directly from ActiveRecord::Base or an abstract class, if any, in the inheritance hierarchy.

    # File lib/active_record/base.rb, line 1205
    def class_of_active_record_descendant(klass)
      if klass.superclass == Base || klass.superclass.abstract_class?
        klass
      elsif klass.superclass.nil?
        raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord"
      else
        class_of_active_record_descendant(klass.superclass)
      end
    end

compute_type(type_name) click to toggle source

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 lib/active_record/base.rb, line 1177
    def compute_type(type_name)
      if type_name.match(/^::/)
        # If the type is prefixed with a scope operator then we assume that
        # the type_name is an absolute reference.
        ActiveSupport::Dependencies.constantize(type_name)
      else
        # Build a list of candidates to search for
        candidates = []
        name.scan(/::|$/) { candidates.unshift "#{$`}::#{type_name}" }
        candidates << type_name

        candidates.each do |candidate|
          begin
            constant = ActiveSupport::Dependencies.constantize(candidate)
            return constant if candidate == constant.to_s
          rescue NameError => e
            # We don't want to swallow NoMethodError < NameError errors
            raise e unless e.instance_of?(NameError)
          rescue ArgumentError
          end
        end

        raise NameError, "uninitialized constant #{candidates.first}"
      end
    end

default_scope(options = {}) click to toggle source

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

`default_scope` is also applied while creating/building a record. It is not applied while updating a record.

    class Article < ActiveRecord::Base
      default_scope where(:published => true)
    end

    Article.new.published    # => true
    Article.create.published # => true

    # File lib/active_record/base.rb, line 1162
    def default_scope(options = {})
      reset_scoped_methods
      self.default_scoping << construct_finder_arel(options, default_scoping.pop)
    end

expand_hash_conditions_for_aggregates(attrs) click to toggle source

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 lib/active_record/base.rb, line 1258
    def expand_hash_conditions_for_aggregates(attrs)
      expanded_attrs = {}
      attrs.each do |attr, value|
        unless (aggregation = reflect_on_aggregation(attr.to_sym)).nil?
          mapping = aggregate_mapping(aggregation)
          mapping.each do |field_attr, aggregate_attr|
            if mapping.size == 1 && !value.respond_to?(aggregate_attr)
              expanded_attrs[field_attr] = value
            else
              expanded_attrs[field_attr] = value.send(aggregate_attr)
            end
          end
        else
          expanded_attrs[attr] = value
        end
      end
      expanded_attrs
    end

sanitize_conditions(condition, table_name = self.table_name) click to toggle source
Alias for: sanitize_sql
sanitize_sql(condition, table_name = self.table_name) click to toggle source
Also aliased as: sanitize_conditions
Alias for: sanitize_sql_for_conditions
sanitize_sql_array(ary) click to toggle source

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 lib/active_record/base.rb, line 1312
    def sanitize_sql_array(ary)
      statement, *values = ary
      if values.first.is_a?(Hash) and statement =~ /:\w+/
        replace_named_bind_variables(statement, values.first)
      elsif statement.include?('?')
        replace_bind_variables(statement, values)
      elsif statement.blank?
        statement
      else
        statement % values.collect { |value| connection.quote_string(value.to_s) }
      end
    end

sanitize_sql_for_assignment(assignments) click to toggle source

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 lib/active_record/base.rb, line 1234
    def sanitize_sql_for_assignment(assignments)
      case assignments
        when Array; sanitize_sql_array(assignments)
        when Hash;  sanitize_sql_hash_for_assignment(assignments)
        else        assignments
      end
    end

sanitize_sql_for_conditions(condition, table_name = self.table_name) click to toggle source

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 lib/active_record/base.rb, line 1220
    def sanitize_sql_for_conditions(condition, table_name = self.table_name)
      return nil if condition.blank?

      case condition
        when Array; sanitize_sql_array(condition)
        when Hash;  sanitize_sql_hash_for_conditions(condition, table_name)
        else        condition
      end
    end

Also aliased as: sanitize_sql
sanitize_sql_hash(attrs, default_table_name = self.table_name) click to toggle source
Alias for: sanitize_sql_hash_for_conditions
sanitize_sql_hash_for_assignment(attrs) click to toggle source

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 lib/active_record/base.rb, line 1303
    def sanitize_sql_hash_for_assignment(attrs)
      attrs.map do |attr, value|
        "#{connection.quote_column_name(attr)} = #{quote_bound_value(value)}"
      end.join(', ')
    end

sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name) click to toggle source

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 lib/active_record/base.rb, line 1291
    def sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name)
      attrs = expand_hash_conditions_for_aggregates(attrs)

      table = Arel::Table.new(self.table_name, :engine => arel_engine, :as => default_table_name)
      builder = PredicateBuilder.new(arel_engine)
      builder.build_from_hash(attrs, table).map{ |b| b.to_sql }.join(' AND ')
    end

Also aliased as: sanitize_sql_hash
with_exclusive_scope(method_scoping = {}, &block) click to toggle source

Works like with_scope, but discards any nested properties.

    # File lib/active_record/base.rb, line 1128
    def with_exclusive_scope(method_scoping = {}, &block)
      if method_scoping.values.any? { |e| e.is_a?(ActiveRecord::Relation) }
        raise ArgumentError, New finder API can not be used with_exclusive_scope. You can either call unscoped to get an anonymous scope not bound to the default_scope:  User.unscoped.where(:active => true)Or call unscoped with a block:  User.unscoped do    User.where(:active => true).all  end
      end
      with_scope(method_scoping, :overwrite, &block)
    end

with_scope(method_scoping = {}, action = :merge, &block) click to toggle source

with_scope lets you apply options to inner block incrementally. It takes a hash and the keys must be `:find` or `:create`. `:find` parameter is `Relation` while `:create` parameters are an attributes hash.

    class Article < ActiveRecord::Base
      def self.create_with_scope
        with_scope(:find => where(: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 `where`, `includes`, and `joins` operations in `Relation`, which are merged.

`joins` operations 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 => where(:blog_id => 1).limit(1), :create => { :blog_id => 1 }) do
          with_scope(:find => limit(10)) do
            all # => SELECT * from articles WHERE blog_id = 1 LIMIT 10
          end
          with_scope(:find => where(:author_id => 3)) do
            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 => where(:blog_id => 1).limit(1)) do
          with_exclusive_scope(:find => limit(10)) do
            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 lib/active_record/base.rb, line 1087
    def with_scope(method_scoping = {}, action = :merge, &block)
      method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping)

      if method_scoping.is_a?(Hash)
        # Dup first and second level of hash (method and params).
        method_scoping = method_scoping.dup
        method_scoping.each do |method, params|
          method_scoping[method] = params.dup unless params == true
        end

        method_scoping.assert_valid_keys([ :find, :create ])
        relation = construct_finder_arel(method_scoping[:find] || {})

        if current_scoped_methods && current_scoped_methods.create_with_value && method_scoping[:create]
          scope_for_create = if action == :merge
            current_scoped_methods.create_with_value.merge(method_scoping[:create])
          else
            method_scoping[:create]
          end

          relation = relation.create_with(scope_for_create)
        else
          scope_for_create = method_scoping[:create]
          scope_for_create ||= current_scoped_methods.create_with_value if current_scoped_methods
          relation = relation.create_with(scope_for_create) if scope_for_create
        end

        method_scoping = relation
      end

      method_scoping = current_scoped_methods.merge(method_scoping) if current_scoped_methods && action ==  :merge

      self.scoped_methods << method_scoping
      begin
        yield
      ensure
        self.scoped_methods.pop
      end
    end

### Public Instance Methods

==(comparison_object) click to toggle source

Returns true if `comparison_object` is the same exact object, or `comparison_object` is of the same type and `self` has an ID and it is equal to `comparison_object.id`.

Note that new records are different from any other record by definition, unless the other record is the receiver itself. Besides, if you fetch existing records with `select` and leave the ID out, you’re on your own, this predicate will return false.

Note also that destroying a record preserves its ID in the model instance, so deleted models are still comparable.

    # File lib/active_record/base.rb, line 1618
    def ==(comparison_object)
      comparison_object.equal?(self) ||
        (comparison_object.instance_of?(self.class) &&
          comparison_object.id == id && !comparison_object.new_record?)
    end

[](attr_name) click to toggle source

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 lib/active_record/base.rb, line 1517
    def [](attr_name)
      read_attribute(attr_name)
    end

[]=(attr_name, value) click to toggle source

Updates the attribute identified by `attr_name` with the specified `value`. (Alias for the protected write_attribute method).

    # File lib/active_record/base.rb, line 1523
    def []=(attr_name, value)
      write_attribute(attr_name, value)
    end

attribute_for_inspect(attr_name) click to toggle source

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 lib/active_record/base.rb, line 1585
    def attribute_for_inspect(attr_name)
      value = read_attribute(attr_name)

      if value.is_a?(String) && value.length > 50
        "#{value[0..50]}...".inspect
      elsif value.is_a?(Date) || value.is_a?(Time)
        %("#{value.to_s(:db)}")
      else
        value.inspect
      end
    end

attribute_names() click to toggle source

Returns an array of names for the attributes available on this object sorted alphabetically.

    # File lib/active_record/base.rb, line 1510
    def attribute_names
      @attributes.keys.sort
    end

attribute_present?(attribute) click to toggle source

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 lib/active_record/base.rb, line 1599
    def attribute_present?(attribute)
      value = read_attribute(attribute)
      !value.blank?
    end

attributes() click to toggle source

Returns a hash of all the attributes with their names as keys and the values of the attributes as values.

    # File lib/active_record/base.rb, line 1566
    def attributes
      attrs = {}
      attribute_names.each { |name| attrs[name] = read_attribute(name) }
      attrs
    end

attributes=(new_attributes, guard_protected_attributes = true) click to toggle source

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 lib/active_record/base.rb, line 1547
    def attributes=(new_attributes, guard_protected_attributes = true)
      return unless new_attributes.is_a?(Hash)
      attributes = new_attributes.stringify_keys

      multi_parameter_attributes = []
      attributes = sanitize_for_mass_assignment(attributes) if guard_protected_attributes

      attributes.each do |k, v|
        if k.include?("(")
          multi_parameter_attributes << [ k, v ]
        else
          respond_to?(:"#{k}=") ? send(:"#{k}=", v) : raise(UnknownAttributeError, "unknown attribute: #{k}")
        end
      end

      assign_multiparameter_attributes(multi_parameter_attributes)
    end

cache_key() click to toggle source

Returns a cache key that can be used to identify this record.

#### Examples

    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 lib/active_record/base.rb, line 1489
    def cache_key
      case
      when new_record?
        "#{self.class.model_name.cache_key}/new"
      when timestamp = self[:updated_at]
        "#{self.class.model_name.cache_key}/#{id}-#{timestamp.to_s(:number)}"
      else
        "#{self.class.model_name.cache_key}/#{id}"
      end
    end

column_for_attribute(name) click to toggle source

Returns the column object for the named attribute.

    # File lib/active_record/base.rb, line 1605
    def column_for_attribute(name)
      self.class.columns_hash[name.to_s]
    end

connection() click to toggle source

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 lib/active_record/connection_adapters/abstract/connection_specification.rb, line 19
    def connection
      self.class.connection
    end

dup() click to toggle source

Returns duplicated record with unfreezed attributes.

    # File lib/active_record/base.rb, line 1646
    def dup
      obj = super
      obj.instance_variable_set('@attributes', @attributes.dup)
      obj
    end

eql?(comparison_object) click to toggle source

Delegates to ==

    # File lib/active_record/base.rb, line 1625
    def eql?(comparison_object)
      self == (comparison_object)
    end

freeze() click to toggle source

Freeze the attributes hash such that associations are still accessible, even on destroyed records.

    # File lib/active_record/base.rb, line 1636
    def freeze
      @attributes.freeze; self
    end

frozen?() click to toggle source

Returns `true` if the attributes hash has been frozen.

    # File lib/active_record/base.rb, line 1641
    def frozen?
      @attributes.frozen?
    end

has_attribute?(attr_name) click to toggle source

Returns true if the given attribute is in the attributes hash

    # File lib/active_record/base.rb, line 1505
    def has_attribute?(attr_name)
      @attributes.has_key?(attr_name.to_s)
    end

hash() click to toggle source

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 lib/active_record/base.rb, line 1631
    def hash
      id.hash
    end

init_with(coder) click to toggle source

Initialize an empty model object from `coder`. `coder` must contain the attributes necessary for initializing an empty model object. For example:

    class Post < ActiveRecord::Base
    end

    post = Post.allocate
    post.init_with('attributes' => { 'title' => 'hello world' })
    post.title # => 'hello world'

    # File lib/active_record/base.rb, line 1447
    def init_with(coder)
      @attributes = coder['attributes']
      @attributes_cache, @previously_changed, @changed_attributes = {}, {}, {}
      @new_record = @readonly = @destroyed = @marked_for_destruction = false
      _run_find_callbacks
      _run_initialize_callbacks
    end

initialize_copy(other) click to toggle source

Cloned objects have no id assigned and are treated as new records. Note that this is a “shallow” clone as 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 lib/active_record/base.rb, line 1416
    def initialize_copy(other)
      _run_after_initialize_callbacks if respond_to?(:_run_after_initialize_callbacks)
      cloned_attributes = other.clone_attributes(:read_attribute_before_type_cast)
      cloned_attributes.delete(self.class.primary_key)

      @attributes = cloned_attributes

      @changed_attributes = {}
      attributes_from_column_definition.each do |attr, orig_value|
        @changed_attributes[attr] = orig_value if field_changed?(attr, orig_value, @attributes[attr])
      end

      clear_aggregation_cache
      clear_association_cache
      @attributes_cache = {}
      @new_record = true
      ensure_proper_type

      populate_with_current_scope_attributes
    end

inspect() click to toggle source

Returns the contents of the record as a nicely formatted string.

    # File lib/active_record/base.rb, line 1664
    def inspect
      attributes_as_nice_string = self.class.column_names.collect { |name|
        if has_attribute?(name) || new_record?
          "#{name}: #{attribute_for_inspect(name)}"
        end
      }.compact.join(", ")
      "#<#{self.class} #{attributes_as_nice_string}>"
    end

readonly!() click to toggle source

Marks this record as read only.

    # File lib/active_record/base.rb, line 1659
    def readonly!
      @readonly = true
    end

readonly?() click to toggle source

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 lib/active_record/base.rb, line 1654
    def readonly?
      @readonly
    end

to_param() click to toggle source

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 `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 lib/active_record/base.rb, line 1477
    def to_param
      # We can't use alias_method here, because method 'id' optimizes itself on the fly.
      id && id.to_s # Be sure to stringify the id for routes
    end

### Protected Instance Methods

clone_attribute_value(reader_method, attribute_name) click to toggle source

    # File lib/active_record/base.rb, line 1681
    def clone_attribute_value(reader_method, attribute_name)
      value = send(reader_method, attribute_name)
      value.duplicable? ? value.clone : value
    rescue TypeError, NoMethodError
      value
    end

clone_attributes(reader_method = :read_attribute, attributes = {}) click to toggle source

    # File lib/active_record/base.rb, line 1674
    def clone_attributes(reader_method = :read_attribute, attributes = {})
      attribute_names.each do |name|
        attributes[name] = clone_attribute_value(reader_method, name)
      end
      attributes
    end

[Validate]

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