Class: ActiveRecord::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/active_record/base.rb,
lib/active_record/connection_adapters/mysql_adapter.rb,
lib/active_record/connection_adapters/sqlite3_adapter.rb,
lib/active_record/connection_adapters/postgresql_adapter.rb,
lib/active_record/connection_adapters/abstract/connection_specification.rb

Overview

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.

Direct Known Subclasses

SessionStore::Session

Defined Under Namespace

Classes: ConnectionSpecification

Constant Summary collapse

@@configurations = 
{}
@@primary_key_prefix_type = 
nil
@@pluralize_table_names = 
true
@@default_timezone = 
:local
@@schema_format = 
:ruby
@@timestamped_migrations = 
true

Class Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(attributes = nil) ⇒ Base

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.



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# File 'lib/active_record/base.rb', line 1399

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

Class Attribute Details

.abstract_class ⇒ Object

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



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# File 'lib/active_record/base.rb', line 834

def abstract_class
  @abstract_class
end

Class Method Details

.===(object) ⇒ Object

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



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# File 'lib/active_record/base.rb', line 819

def ===(object)
  object.is_a?(self)
end

.abstract_class? ⇒ Boolean

Returns whether this class is an abstract class or not.

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 837

def abstract_class?
  defined?(@abstract_class) && @abstract_class == true
end

.arel_engine ⇒ Object 



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# File 'lib/active_record/base.rb', line 859

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 ⇒ Object 



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# File 'lib/active_record/base.rb', line 855

def arel_table
  @arel_table ||= Arel::Table.new(table_name, arel_engine)
end

.attr_readonly(*attributes) ⇒ Object

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



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# File 'lib/active_record/base.rb', line 527

def attr_readonly(*attributes)
  write_inheritable_attribute(:attr_readonly, Set.new(attributes.map { |a| a.to_s }) + (readonly_attributes || []))
end

.attribute_method?(attribute) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 757

def attribute_method?(attribute)
  super || (table_exists? && column_names.include?(attribute.to_s.sub(/=$/, '')))
end

.base_class ⇒ Object

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.



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# File 'lib/active_record/base.rb', line 829

def base_class
  class_of_active_record_descendant(self)
end

.before_remove_const ⇒ Object

:nodoc:



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# File 'lib/active_record/base.rb', line 899

def before_remove_const #:nodoc:
  reset_scoped_methods
end

.colorize_logging(*args) ⇒ Object Also known as: colorize_logging= 



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# File 'lib/active_record/base.rb', line 437

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

.column_methods_hash ⇒ Object

Returns a hash of all the methods added to query each of the columns in the table with the name of the method as the key and true as the value. This makes it possible to do O(1) lookups in respond_to? to check if a given method for attribute is available.



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# File 'lib/active_record/base.rb', line 710

def column_methods_hash #:nodoc:
  @dynamic_methods_hash ||= column_names.inject(Hash.new(false)) do |methods, attr|
    attr_name = attr.to_s
    methods[attr.to_sym]       = attr_name
    methods["#{attr}=".to_sym] = attr_name
    methods["#{attr}?".to_sym] = attr_name
    methods["#{attr}_before_type_cast".to_sym] = attr_name
    methods
  end
end

.column_names ⇒ Object

Returns an array of column names as strings.



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# File 'lib/active_record/base.rb', line 697

def column_names
  @column_names ||= columns.map { |column| column.name }
end

.columns ⇒ Object

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



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# File 'lib/active_record/base.rb', line 683

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 ⇒ Object

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



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# File 'lib/active_record/base.rb', line 692

def columns_hash
  @columns_hash ||= Hash[columns.map { |column| [column.name, column] }]
end

.connected? ⇒ Boolean

Returns true if Active Record is connected.

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/abstract/connection_specification.rb', line 101

def connected?
  connection_handler.connected?(self)
end

.connection ⇒ Object

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.



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# File 'lib/active_record/connection_adapters/abstract/connection_specification.rb', line 88

def connection
  retrieve_connection
end

.connection_pool ⇒ Object 



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# File 'lib/active_record/connection_adapters/abstract/connection_specification.rb', line 92

def connection_pool
  connection_handler.retrieve_connection_pool(self)
end

.content_columns ⇒ Object

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.



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# File 'lib/active_record/base.rb', line 703

def content_columns
  @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
end

.count_by_sql(sql) ⇒ Object

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"



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# File 'lib/active_record/base.rb', line 520

def count_by_sql(sql)
  sql = sanitize_conditions(sql)
  connection.select_value(sql, "#{name} Count").to_i
end

.create(attributes = nil, &block) ⇒ Object

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



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# File 'lib/active_record/base.rb', line 498

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

.descends_from_active_record? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 782

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) ⇒ Object

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.



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# 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) ⇒ Object

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"}>, ...]



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# File 'lib/active_record/base.rb', line 472

def find_by_sql(sql)
  connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) }
end

.finder_needs_type_condition? ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 790

def finder_needs_type_condition? #:nodoc:
  # This is like this because benchmarking justifies the strange :false stuff
  :true == (@finder_needs_type_condition ||= descends_from_active_record? ? :false : :true)
end

.full_table_name_prefix ⇒ Object

:nodoc:



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# File 'lib/active_record/base.rb', line 610

def full_table_name_prefix #:nodoc:
  (parents.detect{ |p| p.respond_to?(:table_name_prefix) } || self).table_name_prefix
end

.i18n_scope ⇒ Object

Set the i18n scope to overwrite ActiveModel.



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# File 'lib/active_record/base.rb', line 777

def i18n_scope #:nodoc:
  :activerecord
end

.inheritance_column ⇒ Object

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



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# File 'lib/active_record/base.rb', line 616

def inheritance_column
  @inheritance_column ||= "type"
end

.inspect ⇒ Object

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



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# File 'lib/active_record/base.rb', line 796

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

.lookup_ancestors ⇒ Object

Set the lookup ancestors for ActiveModel.



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# File 'lib/active_record/base.rb', line 762

def lookup_ancestors #:nodoc:
  klass = self
  classes = [klass]
  while klass != klass.base_class
    classes << klass = klass.superclass
  end
  classes
rescue
  # OPTIMIZE this rescue is to fix this test: ./test/cases/reflection_test.rb:56:in `test_human_name_for_column'
  # Apparently the method base_class causes some trouble.
  # It now works for sure.
  [self]
end

.mysql_connection(config) ⇒ Object

Establishes a connection to the database that’s used by all Active Record objects.



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# File 'lib/active_record/connection_adapters/mysql_adapter.rb', line 9

def self.mysql_connection(config) # :nodoc:
  config = config.symbolize_keys
  host     = config[:host]
  port     = config[:port]
  socket   = config[:socket]
  username = config[:username] ? config[:username].to_s : 'root'
  password = config[:password].to_s
  database = config[:database]

  unless defined? Mysql
    begin
      require 'mysql'
    rescue LoadError
      raise "!!! Missing the mysql2 gem. Add it to your Gemfile: gem 'mysql2'"
    end

    unless defined?(Mysql::Result) && Mysql::Result.method_defined?(:each_hash)
      raise "!!! Outdated mysql gem. Upgrade to 2.8.1 or later. In your Gemfile: gem 'mysql', '2.8.1'. Or use gem 'mysql2'"
    end
  end

  mysql = Mysql.init
  mysql.ssl_set(config[:sslkey], config[:sslcert], config[:sslca], config[:sslcapath], config[:sslcipher]) if config[:sslca] || config[:sslkey]

  default_flags = Mysql.const_defined?(:CLIENT_MULTI_RESULTS) ? Mysql::CLIENT_MULTI_RESULTS : 0
  default_flags |= Mysql::CLIENT_FOUND_ROWS if Mysql.const_defined?(:CLIENT_FOUND_ROWS)
  options = [host, username, password, database, port, socket, default_flags]
  ConnectionAdapters::MysqlAdapter.new(mysql, logger, options, config)
end

.postgresql_connection(config) ⇒ Object

Establishes a connection to the database that’s used by all Active Record objects



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 8

def self.postgresql_connection(config) # :nodoc:
  require 'pg'

  config = config.symbolize_keys
  host     = config[:host]
  port     = config[:port] || 5432
  username = config[:username].to_s if config[:username]
  password = config[:password].to_s if config[:password]

  if config.has_key?(:database)
    database = config[:database]
  else
    raise ArgumentError, "No database specified. Missing argument: database."
  end

  # The postgres drivers don't allow the creation of an unconnected PGconn object,
  # so just pass a nil connection object for the time being.
  ConnectionAdapters::PostgreSQLAdapter.new(nil, logger, [host, port, nil, nil, database, username, password], config)
end

.quote_value(value, column = nil) ⇒ Object

:nodoc:



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# File 'lib/active_record/base.rb', line 809

def quote_value(value, column = nil) #:nodoc:
  connection.quote(value,column)
end

.quoted_table_name ⇒ Object

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



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# File 'lib/active_record/base.rb', line 601

def quoted_table_name
  @quoted_table_name ||= connection.quote_table_name(table_name)
end

.readonly_attributes ⇒ Object

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



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# File 'lib/active_record/base.rb', line 532

def readonly_attributes
  read_inheritable_attribute(:attr_readonly) || []
end

.remove_connection(klass = self) ⇒ Object 



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# 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 ⇒ Object

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



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# File 'lib/active_record/base.rb', line 747

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

.reset_column_information_and_inheritable_attributes_for_all_subclasses ⇒ Object

:nodoc:



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# File 'lib/active_record/base.rb', line 753

def reset_column_information_and_inheritable_attributes_for_all_subclasses#:nodoc:
  descendants.each { |klass| klass.reset_inheritable_attributes; klass.reset_column_information }
end

.reset_sequence_name ⇒ Object

:nodoc:



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# File 'lib/active_record/base.rb', line 626

def reset_sequence_name #:nodoc:
  default = connection.default_sequence_name(table_name, primary_key)
  set_sequence_name(default)
  default
end

.reset_subclasses ⇒ Object

:nodoc:



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# File 'lib/active_record/base.rb', line 325

def reset_subclasses #:nodoc:
  ActiveSupport::Deprecation.warn 'ActiveRecord::Base.reset_subclasses no longer does anything in Rails 3. It will be removed in the final release; please update your apps and plugins.', caller
end

.reset_table_name ⇒ Object

Computes the table name, (re)sets it internally, and returns it.



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# File 'lib/active_record/base.rb', line 606

def reset_table_name #:nodoc:
  self.table_name = compute_table_name
end

.respond_to?(method_id, include_private = false) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 841

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 ⇒ Object 



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# File 'lib/active_record/connection_adapters/abstract/connection_specification.rb', line 96

def retrieve_connection
  connection_handler.retrieve_connection(self)
end

.sanitize(object) ⇒ Object

Used to sanitize objects before they’re used in an SQL SELECT statement. Delegates to connection.quote.



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# File 'lib/active_record/base.rb', line 814

def sanitize(object) #:nodoc:
  connection.quote(object)
end

.scoped_methods ⇒ Object

:nodoc:



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# File 'lib/active_record/base.rb', line 894

def scoped_methods #:nodoc:
  key = :"#{self}_scoped_methods"
  Thread.current[key] = Thread.current[key].presence || self.default_scoping.dup
end

.sequence_name ⇒ Object

Lazy-set the sequence name to the connection’s default. This method is only ever called once since set_sequence_name overrides it.



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# File 'lib/active_record/base.rb', line 622

def sequence_name #:nodoc:
  reset_sequence_name
end

.serialize(attr_name, class_name = Object) ⇒ Object

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



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# File 'lib/active_record/base.rb', line 551

def serialize(attr_name, class_name = Object)
  serialized_attributes[attr_name.to_s] = class_name
end

.serialized_attributes ⇒ Object

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



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# File 'lib/active_record/base.rb', line 557

def serialized_attributes
  read_inheritable_attribute(:attr_serialized) or write_inheritable_attribute(:attr_serialized, {})
end

.set_inheritance_column(value = nil, &block) ⇒ Object Also known as: inheritance_column=

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



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# File 'lib/active_record/base.rb', line 653

def set_inheritance_column(value = nil, &block)
  define_attr_method :inheritance_column, value, &block
end

.set_sequence_name(value = nil, &block) ⇒ Object Also known as: sequence_name=

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



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# File 'lib/active_record/base.rb', line 672

def set_sequence_name(value = nil, &block)
  define_attr_method :sequence_name, value, &block
end

.set_table_name(value = nil, &block) ⇒ Object Also known as: table_name=

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



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# File 'lib/active_record/base.rb', line 638

def set_table_name(value = nil, &block)
  @quoted_table_name = nil
  define_attr_method :table_name, value, &block
end

.sqlite3_connection(config) ⇒ Object

sqlite3 adapter reuses sqlite_connection.



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# File 'lib/active_record/connection_adapters/sqlite3_adapter.rb', line 6

def self.sqlite3_connection(config) # :nodoc:
  # Require database.
  unless config[:database]
    raise ArgumentError, "No database file specified. Missing argument: database"
  end

  # Allow database path relative to Rails.root, but only if
  # the database path is not the special path that tells
  # Sqlite to build a database only in memory.
  if defined?(Rails.root) && ':memory:' != config[:database]
    config[:database] = File.expand_path(config[:database], Rails.root)
  end

  unless 'sqlite3' == config[:adapter]
    raise ArgumentError, 'adapter name should be "sqlite3"'
  end

  unless self.class.const_defined?(:SQLite3)
    require_library_or_gem(config[:adapter])
  end

  db = SQLite3::Database.new(
    config[:database],
    :results_as_hash => true
  )

  db.busy_timeout(config[:timeout]) unless config[:timeout].nil?

  ConnectionAdapters::SQLite3Adapter.new(db, logger, config)
end

.sti_name ⇒ Object 



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# File 'lib/active_record/base.rb', line 851

def sti_name
  store_full_sti_class ? name : name.demodulize
end

.subclasses ⇒ Object 



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# File 'lib/active_record/base.rb', line 329

def subclasses
  descendants
end

.table_exists? ⇒ Boolean

Indicates whether the table associated with this class exists

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 678

def table_exists?
  connection.table_exists?(table_name)
end

.table_name ⇒ Object

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



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# File 'lib/active_record/base.rb', line 596

def table_name
  reset_table_name
end

.unscoped ⇒ Object

Returns a scope for this class without taking into account the default_scope.

class Post < ActiveRecord::Base
  default_scope :published => true
end

Post.all          # Fires "SELECT * FROM posts WHERE published = true"
Post.unscoped.all # Fires "SELECT * FROM posts"

This method also accepts a block meaning that all queries inside the block will not use the default_scope:

Post.unscoped {
  limit(10) # Fires "SELECT * FROM posts LIMIT 10"
}

It is recommended to use block form of unscoped because chaining unscoped with named_scope does not work. Assuming that published is a named_scope following two statements are same.

Post.unscoped.published Post.published



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# File 'lib/active_record/base.rb', line 890

def unscoped #:nodoc:
  block_given? ? relation.scoping { yield } : relation
end

Instance Method Details

#==(comparison_object) ⇒ Object

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.



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# File 'lib/active_record/base.rb', line 1624

def ==(comparison_object)
  comparison_object.equal?(self) ||
    (comparison_object.instance_of?(self.class) &&
      comparison_object.id == id && !comparison_object.new_record?)
end

#[](attr_name) ⇒ Object

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).



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# File 'lib/active_record/base.rb', line 1523

def [](attr_name)
  read_attribute(attr_name)
end

#[]=(attr_name, value) ⇒ Object

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



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# File 'lib/active_record/base.rb', line 1529

def []=(attr_name, value)
  write_attribute(attr_name, value)
end

#attribute_for_inspect(attr_name) ⇒ Object

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"'



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# File 'lib/active_record/base.rb', line 1591

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 ⇒ Object

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



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# File 'lib/active_record/base.rb', line 1516

def attribute_names
  @attributes.keys.sort
end

#attribute_present?(attribute) ⇒ Boolean

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).

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 1605

def attribute_present?(attribute)
  value = read_attribute(attribute)
  !value.blank?
end

#attributes ⇒ Object

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



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# File 'lib/active_record/base.rb', line 1572

def attributes
  attrs = {}
  attribute_names.each { |name| attrs[name] = read_attribute(name) }
  attrs
end

#attributes=(new_attributes, guard_protected_attributes = true) ⇒ Object

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



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# File 'lib/active_record/base.rb', line 1553

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 ⇒ Object

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)



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# File 'lib/active_record/base.rb', line 1495

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) ⇒ Object

Returns the column object for the named attribute.



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# File 'lib/active_record/base.rb', line 1611

def column_for_attribute(name)
  self.class.columns_hash[name.to_s]
end

#configurations ⇒ Object

:singleton-method: 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'
   }
}



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# File 'lib/active_record/base.rb', line 363

cattr_accessor :configurations, :instance_writer => false

#connection ⇒ Object

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.



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# File 'lib/active_record/connection_adapters/abstract/connection_specification.rb', line 19

def connection
  self.class.connection
end

#connection_handler ⇒ Object

:singleton-method: The connection handler



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# File 'lib/active_record/connection_adapters/abstract/connection_specification.rb', line 13

class_attribute :connection_handler, :instance_writer => false

#default_timezone ⇒ Object

:singleton-method: 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.



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# File 'lib/active_record/base.rb', line 408

cattr_accessor :default_timezone, :instance_writer => false

#dup ⇒ Object

Returns duplicated record with unfreezed attributes.



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# File 'lib/active_record/base.rb', line 1652

def dup
  obj = super
  obj.instance_variable_set('@attributes', @attributes.dup)
  obj
end

#eql?(comparison_object) ⇒ Boolean

Delegates to ==

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 1631

def eql?(comparison_object)
  self == (comparison_object)
end

#freeze ⇒ Object

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



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# File 'lib/active_record/base.rb', line 1642

def freeze
  @attributes.freeze; self
end

#frozen? ⇒ Boolean

Returns true if the attributes hash has been frozen.

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 1647

def frozen?
  @attributes.frozen?
end

#has_attribute?(attr_name) ⇒ Boolean

Returns true if the given attribute is in the attributes hash

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 1511

def has_attribute?(attr_name)
  @attributes.has_key?(attr_name.to_s)
end

#hash ⇒ Object

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) ]



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# File 'lib/active_record/base.rb', line 1637

def hash
  id.hash
end

#init_with(coder) ⇒ Object

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'



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# File 'lib/active_record/base.rb', line 1453

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) ⇒ Object

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.



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# File 'lib/active_record/base.rb', line 1422

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 ⇒ Object

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



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# File 'lib/active_record/base.rb', line 1670

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

#logger ⇒ Object

:singleton-method: 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.



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# File 'lib/active_record/base.rb', line 322

cattr_accessor :logger, :instance_writer => false

#pluralize_table_names ⇒ Object

:singleton-method: 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.



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# File 'lib/active_record/base.rb', line 401

cattr_accessor :pluralize_table_names, :instance_writer => false

#primary_key_prefix_type ⇒ Object

:singleton-method: 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.



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# File 'lib/active_record/base.rb', line 373

cattr_accessor :primary_key_prefix_type, :instance_writer => false

#quoted_id ⇒ Object

:nodoc:



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# File 'lib/active_record/base.rb', line 1506

def quoted_id #:nodoc:
  quote_value(id, column_for_attribute(self.class.primary_key))
end

#readonly! ⇒ Object

Marks this record as read only.



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# File 'lib/active_record/base.rb', line 1665

def readonly!
  @readonly = true
end

#readonly? ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File 'lib/active_record/base.rb', line 1660

def readonly?
  @readonly
end

#schema_format ⇒ Object

:singleton-method: 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.



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# File 'lib/active_record/base.rb', line 419

cattr_accessor :schema_format , :instance_writer => false

#table_name_prefix ⇒ Object

:singleton-method: 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.



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# File 'lib/active_record/base.rb', line 386

class_attribute :table_name_prefix, :instance_writer => false

#table_name_suffix ⇒ Object

:singleton-method: 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.



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# File 'lib/active_record/base.rb', line 393

class_attribute :table_name_suffix, :instance_writer => false

#timestamped_migrations ⇒ Object

:singleton-method: Specify whether or not to use timestamps for migration versions



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# File 'lib/active_record/base.rb', line 425

cattr_accessor :timestamped_migrations , :instance_writer => false

#to_param ⇒ Object

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"



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# File 'lib/active_record/base.rb', line 1483

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