Class: ActiveRecord::Associations::CollectionAssociation

Inherits:
Association show all
Defined in:
activerecord/lib/active_record/associations/collection_association.rb

Overview

Active Record Association Collection

CollectionAssociation is an abstract class that provides common stuff to ease the implementation of association proxies that represent collections. See the class hierarchy in Association.

CollectionAssociation:
  HasManyAssociation => has_many
    HasManyThroughAssociation + ThroughAssociation => has_many :through

The CollectionAssociation class provides common methods to the collections defined by has_and_belongs_to_many, has_many or has_many with the :through association option.

You need to be careful with assumptions regarding the target: The proxy does not fetch records from the database until it needs them, but new ones created with build are added to the target. So, the target may be non-empty and still lack children waiting to be read from the database. If you look directly to the database you cannot assume that's the entire collection because new records may have been added to the target, etc.

If you need to work on all current children, new and existing records, load_target and the loaded flag are your friends.

Direct Known Subclasses

HasManyAssociation

Instance Attribute Summary

Attributes inherited from Association

#owner, #reflection, #target

Instance Method Summary collapse

Methods inherited from Association

#create, #create!, #extensions, #initialize, #initialize_attributes, #inversed_from, #klass, #loaded!, #loaded?, #marshal_dump, #marshal_load, #reload, #remove_inverse_instance, #reset_negative_cache, #reset_scope, #scoping, #set_inverse_instance, #set_inverse_instance_from_queries, #stale_target?

Constructor Details

This class inherits a constructor from ActiveRecord::Associations::Association

Instance Method Details

#add_to_target(record, skip_callbacks = false, &block) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 281

def add_to_target(record, skip_callbacks = false, &block)
  if association_scope.distinct_value
    index = @target.index(record)
  end
  replace_on_target(record, index, skip_callbacks, &block)
end

#build(attributes = nil, &block) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 104

def build(attributes = nil, &block)
  if attributes.is_a?(Array)
    attributes.collect { |attr| build(attr, &block) }
  else
    add_to_target(build_record(attributes, &block))
  end
end

#concat(*records) ⇒ Object

Add records to this association. Since << flattens its argument list and inserts each record, push and concat behave identically.


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 114

def concat(*records)
  records = records.flatten
  if owner.new_record?
    load_target
    concat_records(records)
  else
    transaction { concat_records(records) }
  end
end

#delete(*records) ⇒ Object

Removes records from this association calling before_remove and after_remove callbacks.

This method is abstract in the sense that delete_records has to be provided by descendants. Note this method does not imply the records are actually removed from the database, that depends precisely on delete_records. They are in any case removed from the collection.


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 188

def delete(*records)
  delete_or_destroy(records, options[:dependent])
end

#delete_all(dependent = nil) ⇒ Object

Removes all records from the association without calling callbacks on the associated records. It honors the :dependent option. However if the :dependent value is :destroy then in that case the :delete_all deletion strategy for the association is applied.

You can force a particular deletion strategy by passing a parameter.

Example:

@author.books.delete_all(:nullify) @author.books.delete_all(:delete_all)

See delete for more info.


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 152

def delete_all(dependent = nil)
  if dependent && ![:nullify, :delete_all].include?(dependent)
    raise ArgumentError, "Valid values are :nullify or :delete_all"
  end

  dependent = if dependent
    dependent
  elsif options[:dependent] == :destroy
    :delete_all
  else
    options[:dependent]
  end

  delete_or_nullify_all_records(dependent).tap do
    reset
    loaded!
  end
end

#destroy(*records) ⇒ Object

Deletes the records and removes them from this association calling before_remove , after_remove , before_destroy and after_destroy callbacks.

Note that this method removes records from the database ignoring the :dependent option.


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 197

def destroy(*records)
  delete_or_destroy(records, :destroy)
end

#destroy_allObject

Destroy all the records from this association.

See destroy for more info.


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 174

def destroy_all
  destroy(load_target).tap do
    reset
    loaded!
  end
end

#empty?Boolean

Returns true if the collection is empty.

If the collection has been loaded it is equivalent to collection.size.zero?. If the collection has not been loaded, it is equivalent to collection.exists?. If the collection has not already been loaded and you are going to fetch the records anyway it is better to check collection.length.zero?.

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 234

def empty?
  if loaded? || @association_ids || reflection.has_cached_counter?
    size.zero?
  else
    target.empty? && !scope.exists?
  end
end

#find(*args) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 81

def find(*args)
  if options[:inverse_of] && loaded?
    args_flatten = args.flatten
    model = scope.klass

    if args_flatten.blank?
      error_message = "Couldn't find #{model.name} without an ID"
      raise RecordNotFound.new(error_message, model.name, model.primary_key, args)
    end

    result = find_by_scan(*args)

    result_size = Array(result).size
    if !result || result_size != args_flatten.size
      scope.raise_record_not_found_exception!(args_flatten, result_size, args_flatten.size)
    else
      result
    end
  else
    scope.find(*args)
  end
end

#find_from_target?Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 309

def find_from_target?
  loaded? ||
    owner.new_record? ||
    target.any? { |record| record.new_record? || record.changed? }
end

#ids_readerObject

Implements the ids reader method, e.g. foo.item_ids for Foo.has_many :items


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

def ids_reader
  if loaded?
    target.pluck(reflection.association_primary_key)
  elsif !target.empty?
    load_target.pluck(reflection.association_primary_key)
  else
    @association_ids ||= scope.pluck(reflection.association_primary_key)
  end
end

#ids_writer(ids) ⇒ Object

Implements the ids writer method, e.g. foo.item_ids= for Foo.has_many :items


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 56

def ids_writer(ids)
  primary_key = reflection.association_primary_key
  pk_type = klass.type_for_attribute(primary_key)
  ids = Array(ids).compact_blank
  ids.map! { |i| pk_type.cast(i) }

  records = klass.where(primary_key => ids).index_by do |r|
    r.public_send(primary_key)
  end.values_at(*ids).compact

  if records.size != ids.size
    found_ids = records.map { |record| record.public_send(primary_key) }
    not_found_ids = ids - found_ids
    klass.all.raise_record_not_found_exception!(ids, records.size, ids.size, primary_key, not_found_ids)
  else
    replace(records)
  end
end

#include?(record) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 260

def include?(record)
  if record.is_a?(reflection.klass)
    if record.new_record?
      include_in_memory?(record)
    else
      loaded? ? target.include?(record) : scope.exists?(record.id)
    end
  else
    false
  end
end

#load_targetObject


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

def load_target
  if find_target?
    @target = merge_target_lists(find_target, target)
  end

  loaded!
  target
end

#null_scope?Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 305

def null_scope?
  owner.new_record? && !foreign_key_present?
end

#readerObject

Implements the reader method, e.g. foo.items for Foo.has_many :items


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 30

def reader
  if stale_target?
    reload
  end

  @proxy ||= CollectionProxy.create(klass, self)
  @proxy.reset_scope
end

#replace(other_array) ⇒ Object

Replace this collection with other_array. This will perform a diff and delete/add only records that have changed.


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 244

def replace(other_array)
  other_array.each { |val| raise_on_type_mismatch!(val) }
  original_target = load_target.dup

  if owner.new_record?
    replace_records(other_array, original_target)
  else
    replace_common_records_in_memory(other_array, original_target)
    if other_array != original_target
      transaction { replace_records(other_array, original_target) }
    else
      other_array
    end
  end
end

#resetObject


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 75

def reset
  super
  @target = []
  @association_ids = nil
end

#scopeObject


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 299

def scope
  scope = super
  scope.none! if null_scope?
  scope
end

#sizeObject

Returns the size of the collection by executing a SELECT COUNT(*) query if the collection hasn't been loaded, and calling collection.size if it has.

If the collection has been already loaded size and length are equivalent. If not and you are going to need the records anyway length will take one less query. Otherwise size is more efficient.

This method is abstract in the sense that it relies on count_records, which is a method descendants have to provide.


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 211

def size
  if !find_target? || loaded?
    target.size
  elsif @association_ids
    @association_ids.size
  elsif !association_scope.group_values.empty?
    load_target.size
  elsif !association_scope.distinct_value && !target.empty?
    unsaved_records = target.select(&:new_record?)
    unsaved_records.size + count_records
  else
    count_records
  end
end

#target=(record) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 288

def target=(record)
  return super unless ActiveRecord::Base.has_many_inversing

  case record
  when Array
    super
  else
    add_to_target(record, true)
  end
end

#transaction(*args) ⇒ Object

Starts a transaction in the association class's database connection.

class Author < ActiveRecord::Base
  has_many :books
end

Author.first.books.transaction do
  # same effect as calling Book.transaction
end

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 133

def transaction(*args)
  reflection.klass.transaction(*args) do
    yield
  end
end

#writer(records) ⇒ Object

Implements the writer method, e.g. foo.items= for Foo.has_many :items


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 40

def writer(records)
  replace(records)
end