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

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

Instance Attribute Summary

Attributes inherited from Association

#inversed, #owner, #reflection, #target

Instance Method Summary collapse

Methods inherited from Association

#aliased_table_name, #association_scope, #initialize, #initialize_attributes, #interpolate, #klass, #loaded!, #loaded?, #marshal_dump, #marshal_load, #reload, #reset_scope, #set_inverse_instance, #stale_target?, #target_scope

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 410

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

#any?Boolean

Returns true if the collections is not empty. Equivalent to !collection.empty?.

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 347

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

#build(attributes = {}, &block) ⇒ Object


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

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

#concat(*records) ⇒ Object

Add records to this association. Returns self so method calls may be chained. 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 174

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

#count(column_name = nil, count_options = {}) ⇒ Object

Count all records using SQL. Construct options and pass them with scope to the target class's count.


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 242

def count(column_name = nil, count_options = {})
  # TODO: Remove count_options argument as soon we remove support to
  # activerecord-deprecated_finders.
  column_name, count_options = nil, column_name if column_name.is_a?(Hash)

  relation = scope
  if association_scope.distinct_value    # This is needed because 'SELECT count(DISTINCT *)..' is not valid SQL.

    column_name ||= reflection.klass.primary_key
    relation = relation.distinct
  end

  value = relation.count(column_name)

  limit  = options[:limit]
  offset = options[:offset]

  if limit || offset
    [ [value - offset.to_i, 0].max, limit.to_i ].min
  else
    value
  end
end

#create(attributes = {}, &block) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 163

def create(attributes = {}, &block)
  _create_record(attributes, &block)
end

#create!(attributes = {}, &block) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 167

def create!(attributes = {}, &block)
  _create_record(attributes, true, &block)
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 273

def delete(*records)
  return if records.empty?
  _options = records.extract_options!
  dependent = _options[:dependent] || options[:dependent]

  records = find(records) if records.any? { |record| record.kind_of?(Integer) || record.kind_of?(String) }
  delete_or_destroy(records, 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 211

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 287

def destroy(*records)
  return if records.empty?
  records = find(records) if records.any? { |record| record.kind_of?(Integer) || record.kind_of?(String) }
  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 233

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

#distinctObject Also known as: uniq


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 365

def distinct
  seen = {}
  load_target.find_all do |record|
    seen[record.id] = true unless seen.key?(record.id)
  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 337

def empty?
  if loaded?
    size.zero?
  else
    @target.blank? && !scope.exists?
  end
end

#fifth(*args) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 131

def fifth(*args)
  first_nth_or_last(:fifth, *args)
end

#find(*args) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 94

def find(*args)
  if block_given?
    load_target.find(*args) { |*block_args| yield(*block_args) }
  else
    if options[:inverse_of] && loaded?
      args_flatten = args.flatten
      raise RecordNotFound, "Couldn't find #{scope.klass.name} without an ID" if args_flatten.blank?
      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
end

#first(*args) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 115

def first(*args)
  first_nth_or_last(:first, *args)
end

#forty_two(*args) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 135

def forty_two(*args)
  first_nth_or_last(:forty_two, *args)
end

#fourth(*args) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 127

def fourth(*args)
  first_nth_or_last(:fourth, *args)
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 51

def ids_reader
  if loaded?
    load_target.map do |record|
      record.send(reflection.association_primary_key)
    end
  else
    column  = "#{reflection.quoted_table_name}.#{reflection.association_primary_key}"
    scope.pluck(column)
  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 63

def ids_writer(ids)
  pk_column = reflection.association_primary_key
  pk_type = klass.type_for_attribute(pk_column)
  ids = Array(ids).reject(&:blank?).map do |i|
    pk_type.type_cast_from_user(i)
  end

  objs = klass.where(pk_column => ids).index_by do |r|
    r.send(pk_column)
  end.values_at(*ids).compact

  if objs.size == ids.size
    replace(objs.index_by { |r| r.send(pk_column) }.values_at(*ids))
  else
    klass.all.raise_record_not_found_exception!(ids, objs.size, ids.size)
  end
end

#include?(record) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 389

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

#last(*args) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 139

def last(*args)
  first_nth_or_last(:last, *args)
end

#lengthObject

Returns the size of the collection calling size on the target.

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


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 325

def length
  load_target.size
end

#load_targetObject


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 401

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

  loaded!
  target
end

#many?Boolean

Returns true if the collection has more than 1 record. Equivalent to collection.size > 1.

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 357

def many?
  if block_given?
    load_target.many? { |*block_args| yield(*block_args) }
  else
    size > 1
  end
end

#null_scope?Boolean

Returns:

  • (Boolean)

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 439

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

#reader(force_reload = false) ⇒ Object

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 29

def reader(force_reload = false)
  if force_reload
    klass.uncached { reload }
  elsif stale_target?
    reload
  end

  if owner.new_record?    # Cache the proxy separately before the owner has an id
    # or else a post-save proxy will still lack the id

    @new_record_proxy ||= CollectionProxy.create(klass, self)
  else
    @proxy ||= CollectionProxy.create(klass, self)
  end
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 375

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) }
    end
  end
end

#replace_on_target(record, index, skip_callbacks) {|record| ... } ⇒ Object

Yields:

  • (record)

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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 417

def replace_on_target(record, index, skip_callbacks)
  callback(:before_add, record) unless skip_callbacks
  yield(record) if block_given?

  if index
    @target[index] = record
  else
    @target << record
  end

  callback(:after_add, record) unless skip_callbacks
  set_inverse_instance(record)

  record
end

#resetObject


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

def reset
  super
  @target = []
end

#scope(opts = {}) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 433

def scope(opts = {})
  scope = super()
  scope.none! if opts.fetch(:nullify, true) && null_scope?
  scope
end

#second(*args) ⇒ Object


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

def second(*args)
  first_nth_or_last(:second, *args)
end

#select(*fields) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 86

def select(*fields)
  if block_given?
    load_target.select.each { |e| yield e }
  else
    scope.select(*fields)
  end
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 303

def size
  if !find_target? || loaded?
    if association_scope.distinct_value
      target.uniq.size
    else
      target.size
    end
  elsif !loaded? && !association_scope.group_values.empty?
    load_target.size
  elsif !loaded? && !association_scope.distinct_value && target.is_a?(Array)
    unsaved_records = target.select { |r| r.new_record? }
    unsaved_records.size + count_records
  else
    count_records
  end
end

#take(n = nil) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 143

def take(n = nil)
  if loaded?
    n ? target.take(n) : target.first
  else
    scope.take(n).tap do |record|
      set_inverse_instance record if record.is_a? ActiveRecord::Base
    end
  end
end

#third(*args) ⇒ Object


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 123

def third(*args)
  first_nth_or_last(:third, *args)
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 192

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 46

def writer(records)
  replace(records)
end