Class: ActiveRecord::Relation

Inherits:
Object
  • Object
show all
Includes:
Batches, Calculations, FinderMethods, QueryMethods, SpawnMethods
Defined in:
activerecord/lib/active_record/relation.rb

Overview

Active Record Relation

Defined Under Namespace

Classes: JoinOperation

Constant Summary

ASSOCIATION_METHODS = 
[:includes, :eager_load, :preload]
MULTI_VALUE_METHODS = 
[:select, :group, :order, :joins, :where, :having]
SINGLE_VALUE_METHODS = 
[:limit, :offset, :lock, :readonly, :create_with, :from]

Constants included from SpawnMethods

SpawnMethods::VALID_FIND_OPTIONS

Instance Attribute Summary (collapse)

Attributes included from QueryMethods

#create_with_value, #eager_load_values, #from_value, #group_values, #having_values, #includes_values, #joins_values, #limit_value, #lock_value, #offset_value, #order_values, #preload_values, #readonly_value, #reorder_flag, #select_values, #where_values

Instance Method Summary (collapse)

Methods included from Batches

#find_each, #find_in_batches

Methods included from QueryMethods

#arel, #build_arel, #create_with, #custom_join_sql, #eager_load, #extending, #from, #group, #having, #includes, #joins, #limit, #lock, #offset, #order, #preload, #readonly, #reorder, #reverse_order, #select, #where

Methods included from ActiveSupport::Concern

#append_features, extended, #included

Methods included from SpawnMethods

#apply_finder_options, #except, #merge, #only

Methods included from Calculations

#average, #calculate, #count, #maximum, #minimum, #sum

Methods included from FinderMethods

#all, #exists?, #find, #first, #last

Constructor Details

- (Relation) initialize(klass, table)

A new instance of Relation



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# File 'activerecord/lib/active_record/relation.rb', line 20

def initialize(klass, table)
  @klass, @table = klass, table

  @implicit_readonly = nil
  @loaded            = false

  SINGLE_VALUE_METHODS.each {|v| instance_variable_set(:@#{v}_value", nil)}
  (ASSOCIATION_METHODS + MULTI_VALUE_METHODS).each {|v| instance_variable_set(:@#{v}_values", [])}
  @extensions = []
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

- (Object) method_missing(method, *args, &block) (protected) 



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# File 'activerecord/lib/active_record/relation.rb', line 361

def method_missing(method, *args, &block)
  if Array.method_defined?(method)
    to_a.send(method, *args, &block)
  elsif @klass.scopes[method]
    merge(@klass.send(method, *args, &block))
  elsif @klass.respond_to?(method)
    scoping { @klass.send(method, *args, &block) }
  elsif arel.respond_to?(method)
    arel.send(method, *args, &block)
  else
    super
  end
end

Instance Attribute Details

- (Object) extensions

Returns the value of attribute extensions



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# File 'activerecord/lib/active_record/relation.rb', line 17

def extensions
  @extensions
end

- (Object) klass (readonly)

Returns the value of attribute klass



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# File 'activerecord/lib/active_record/relation.rb', line 16

def klass
  @klass
end

- (Object) loaded (readonly) Also known as: loaded?

Returns the value of attribute loaded



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# File 'activerecord/lib/active_record/relation.rb', line 16

def loaded
  @loaded
end

- (Object) table (readonly)

Returns the value of attribute table



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# File 'activerecord/lib/active_record/relation.rb', line 16

def table
  @table
end

Instance Method Details

- (Object) ==(other) 



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# File 'activerecord/lib/active_record/relation.rb', line 346

def ==(other)
  case other
  when Relation
    other.to_sql == to_sql
  when Array
    to_a == other.to_a
  end
end

- (Boolean) any?

Returns:

  • (Boolean) 


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# File 'activerecord/lib/active_record/relation.rb', line 93

def any?
  if block_given?
    to_a.any? { |*block_args| yield(*block_args) }
  else
    !empty?
  end
end

- (Object) as_json(options = nil)

:nodoc:



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# File 'activerecord/lib/active_record/relation.rb', line 79

def as_json(options = nil) #:nodoc:
  to_a.as_json(options)
end

- (Object) create(*args, &block) 



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# File 'activerecord/lib/active_record/relation.rb', line 41

def create(*args, &block)
  scoping { @klass.create(*args, &block) }
end

- (Object) create!(*args, &block) 



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# File 'activerecord/lib/active_record/relation.rb', line 45

def create!(*args, &block)
  scoping { @klass.create!(*args, &block) }
end

- (Object) delete(id_or_array)

Deletes the row with a primary key matching the id argument, using a SQL DELETE statement, and returns the number of rows deleted. Active Record objects are not instantiated, so the object's callbacks are not executed, including any :dependent association options or Observer methods.

You can delete multiple rows at once by passing an Array of ids.

Note: Although it is often much faster than the alternative, #destroy, skipping callbacks might bypass business logic in your application that ensures referential integrity or performs other essential jobs.

Examples

# Delete a single row
Todo.delete(1)

# Delete multiple rows
Todo.delete([2,3,4])


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# File 'activerecord/lib/active_record/relation.rb', line 296

def delete(id_or_array)
  where(@klass.primary_key => id_or_array).delete_all
end

- (Object) delete_all(conditions = nil)

Deletes the records matching conditions without instantiating the records first, and hence not calling the destroy method nor invoking callbacks. This is a single SQL DELETE statement that goes straight to the database, much more efficient than destroy_all. Be careful with relations though, in particular :dependent rules defined on associations are not honored. Returns the number of rows affected.

Parameters

  • conditions - Conditions are specified the same way as with find method.

Example

Post.delete_all("person_id = 5 AND (category = 'Something' OR category = 'Else')")
Post.delete_all(["person_id = ? AND (category = ? OR category = ?)", 5, 'Something', 'Else'])

Both calls delete the affected posts all at once with a single DELETE statement. If you need to destroy dependent associations or call your before_* or after_destroy callbacks, use the destroy_all method instead.



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# File 'activerecord/lib/active_record/relation.rb', line 272

def delete_all(conditions = nil)
  conditions ? where(conditions).delete_all : arel.delete.tap { reset }
end

- (Object) destroy(id)

Destroy an object (or multiple objects) that has the given id, the object is instantiated first, therefore all callbacks and filters are fired off before the object is deleted. This method is less efficient than ActiveRecord#delete but allows cleanup methods and other actions to be run.

This essentially finds the object (or multiple objects) with the given id, creates a new object from the attributes, and then calls destroy on it.

Parameters

  • id - Can be either an Integer or an Array of Integers.

Examples

# Destroy a single object
Todo.destroy(1)

# Destroy multiple objects
todos = [1,2,3]
Todo.destroy(todos)


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# File 'activerecord/lib/active_record/relation.rb', line 246

def destroy(id)
  if id.is_a?(Array)
    id.map { |one_id| destroy(one_id) }
  else
    find(id).destroy
  end
end

- (Object) destroy_all(conditions = nil)

Destroys the records matching conditions by instantiating each record and calling its destroy method. Each object's callbacks are executed (including :dependent association options and before_destroy/after_destroy Observer methods). Returns the collection of objects that were destroyed; each will be frozen, to reflect that no changes should be made (since they can't be persisted).

Note: Instantiation, callback execution, and deletion of each record can be time consuming when you're removing many records at once. It generates at least one SQL DELETE query per record (or possibly more, to enforce your callbacks). If you want to delete many rows quickly, without concern for their associations or callbacks, use delete_all instead.

Parameters

  • conditions - A string, array, or hash that specifies which records to destroy. If omitted, all records are destroyed. See the Conditions section in the introduction to ActiveRecord::Base for more information.

Examples

Person.destroy_all("last_login < '2004-04-04'")
Person.destroy_all(:status => "inactive")


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# File 'activerecord/lib/active_record/relation.rb', line 219

def destroy_all(conditions = nil)
  if conditions
    where(conditions).destroy_all
  else
    to_a.each {|object| object.destroy }.tap { reset }
  end
end

- (Boolean) eager_loading?

Returns:

  • (Boolean) 


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# File 'activerecord/lib/active_record/relation.rb', line 342

def eager_loading?
  @should_eager_load ||= (@eager_load_values.any? || (@includes_values.any? && references_eager_loaded_tables?))
end

- (Boolean) empty?

Returns true if there are no records.

Returns:

  • (Boolean) 


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# File 'activerecord/lib/active_record/relation.rb', line 89

def empty?
  loaded? ? @records.empty? : count.zero?
end

- (Object) initialize_copy(other) 



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# File 'activerecord/lib/active_record/relation.rb', line 35

def initialize_copy(other)
  reset
end

- (Object) inspect 



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# File 'activerecord/lib/active_record/relation.rb', line 355

def inspect
  to_a.inspect
end

- (Boolean) many?

Returns:

  • (Boolean) 


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# File 'activerecord/lib/active_record/relation.rb', line 101

def many?
  if block_given?
    to_a.many? { |*block_args| yield(*block_args) }
  else
    @limit_value ? to_a.many? : size > 1
  end
end

- (Object) new(*args, &block) Also known as: build 



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# File 'activerecord/lib/active_record/relation.rb', line 31

def new(*args, &block)
  scoping { @klass.new(*args, &block) }
end

- (Object) primary_key 



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# File 'activerecord/lib/active_record/relation.rb', line 313

def primary_key
  @primary_key ||= table[@klass.primary_key]
end

- (Object) reload 



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# File 'activerecord/lib/active_record/relation.rb', line 300

def reload
  reset
  to_a # force reload
  self
end

- (Object) reset 



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# File 'activerecord/lib/active_record/relation.rb', line 306

def reset
  @first = @last = @to_sql = @order_clause = @scope_for_create = @arel = @loaded = nil
  @should_eager_load = @join_dependency = nil
  @records = []
  self
end

- (Boolean) respond_to?(method, include_private = false)

Returns:

  • (Boolean) 


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# File 'activerecord/lib/active_record/relation.rb', line 49

def respond_to?(method, include_private = false)
  return true if arel.respond_to?(method, include_private) || Array.method_defined?(method) || @klass.respond_to?(method, include_private)

  if match = DynamicFinderMatch.match(method)
    return true if @klass.send(:all_attributes_exists?, match.attribute_names)
  elsif match = DynamicScopeMatch.match(method)
    return true if @klass.send(:all_attributes_exists?, match.attribute_names)
  else
    super
  end
end

- (Object) scope_for_create 



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# File 'activerecord/lib/active_record/relation.rb', line 332

def scope_for_create
  @scope_for_create ||= begin
    if @create_with_value
      @create_with_value.reverse_merge(where_values_hash)
    else
      where_values_hash
    end
  end
end

- (Object) scoping

Scope all queries to the current scope.

Example

Comment.where(:post_id => 1).scoping do
  Comment.first # SELECT * FROM comments WHERE post_id = 1
end

Please check unscoped if you want to remove all previous scopes (including the default_scope) during the execution of a block.



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# File 'activerecord/lib/active_record/relation.rb', line 119

def scoping
  @klass.scoped_methods << self
  begin
    yield
  ensure
    @klass.scoped_methods.pop
  end
end

- (Object) size

Returns size of the records.



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# File 'activerecord/lib/active_record/relation.rb', line 84

def size
  loaded? ? @records.length : count
end

- (Object) to_a 



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# File 'activerecord/lib/active_record/relation.rb', line 61

def to_a
  return @records if loaded?

  @records = eager_loading? ? find_with_associations : @klass.find_by_sql(arel.to_sql)

  preload = @preload_values
  preload +=  @includes_values unless eager_loading?
  preload.each {|associations| @klass.send(:preload_associations, @records, associations) }

  # @readonly_value is true only if set explicitly. @implicit_readonly is true if there
  # are JOINS and no explicit SELECT.
  readonly = @readonly_value.nil? ? @implicit_readonly : @readonly_value
  @records.each { |record| record.readonly! } if readonly

  @loaded = true
  @records
end

- (Object) to_sql 



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# File 'activerecord/lib/active_record/relation.rb', line 317

def to_sql
  @to_sql ||= arel.to_sql
end

- (Object) update(id, attributes)

Updates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.

Parameters

  • id - This should be the id or an array of ids to be updated.

  • attributes - This should be a hash of attributes or an array of hashes.

Examples

# Updates one record
Person.update(15, :user_name => 'Samuel', :group => 'expert')

# Updates multiple records
people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } }
Person.update(people.keys, people.values)


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# File 'activerecord/lib/active_record/relation.rb', line 182

def update(id, attributes)
  if id.is_a?(Array)
    idx = -1
    id.collect { |one_id| idx += 1; update(one_id, attributes[idx]) }
  else
    object = find(id)
    object.update_attributes(attributes)
    object
  end
end

- (Object) update_all(updates, conditions = nil, options = {})

Updates all records with details given if they match a set of conditions supplied, limits and order can also be supplied. This method constructs a single SQL UPDATE statement and sends it straight to the database. It does not instantiate the involved models and it does not trigger Active Record callbacks or validations.

Parameters

  • updates - A string, array, or hash representing the SET part of an SQL statement.

  • conditions - A string, array, or hash representing the WHERE part of an SQL statement. See conditions in the intro.

  • options - Additional options are :limit and :order, see the examples for usage.

Examples

# Update all customers with the given attributes
Customer.update_all :wants_email => true

# Update all books with 'Rails' in their title
Book.update_all "author = 'David'", "title LIKE '%Rails%'"

# Update all avatars migrated more than a week ago
Avatar.update_all ['migrated_at = ?', Time.now.utc], ['migrated_at > ?', 1.week.ago]

# Update all books that match conditions, but limit it to 5 ordered by date
Book.update_all "author = 'David'", "title LIKE '%Rails%'", :order => 'created_at', :limit => 5


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# File 'activerecord/lib/active_record/relation.rb', line 153

def update_all(updates, conditions = nil, options = {})
  if conditions || options.present?
    where(conditions).apply_finder_options(options.slice(:limit, :order)).update_all(updates)
  else
    # Apply limit and order only if they're both present
    if @limit_value.present? == @order_values.present?
      arel.update(Arel::SqlLiteral.new(@klass.send(:sanitize_sql_for_assignment, updates)))
    else
      except(:limit, :order).update_all(updates)
    end
  end
end

- (Object) where_values_hash 



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# File 'activerecord/lib/active_record/relation.rb', line 321

def where_values_hash
  Hash[@where_values.find_all { |w|
    w.respond_to?(:operator) && w.operator == :== && w.left.relation.name == table_name
  }.map { |where|
    [
      where.left.name,
      where.right.respond_to?(:value) ? where.right.value : where.right
    ]
  }]
end