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 AssociationProxy.

CollectionAssociation:
  HasAndBelongsToManyAssociation => has_and_belongs_to_many
  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

#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) {|record| ... } ⇒ Object

Yields:

  • (record)


369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 369

def add_to_target(record)
  callback(:before_add, record)
  yield(record) if block_given?

  if association_scope.distinct_value && index = @target.index(record)
    @target[index] = record
  else
    @target << record
  end

  callback(:after_add, record)
  set_inverse_instance(record)

  record
end

#any?Boolean

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

Returns:

  • (Boolean)


309
310
311
312
313
314
315
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 309

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

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



108
109
110
111
112
113
114
115
116
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 108

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.



129
130
131
132
133
134
135
136
137
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 129

def concat(*records)
  load_target if owner.new_record?

  if owner.new_record?
    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.



200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 200

def count(column_name = nil, count_options = {})
  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



118
119
120
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 118

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

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



122
123
124
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 122

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.



229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 229

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

  if records.first == :all
    if loaded? || dependent == :destroy
      delete_or_destroy(load_target, dependent)
    else
      delete_records(:all, dependent)
    end
  else
    records = find(records) if records.any? { |record| record.kind_of?(Fixnum) || record.kind_of?(String) }
    delete_or_destroy(records, dependent)
  end
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 default 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.



167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 167

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

  dependent = if dependent.present?
                dependent
              elsif options[:dependent] == :destroy
                # since delete_all should not invoke callbacks so use the default deletion strategy
                # for :destroy
                reflection.is_a?(ActiveRecord::Reflection::ThroughReflection) ? :delete_all : :nullify
              else
                options[:dependent]
              end

  delete(:all, dependent: 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.



250
251
252
253
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 250

def destroy(*records)
  records = find(records) if records.any? { |record| record.kind_of?(Fixnum) || record.kind_of?(String) }
  delete_or_destroy(records, :destroy)
end

#destroy_allObject

Destroy all the records from this association.

See destroy for more info.



191
192
193
194
195
196
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 191

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

#distinctObject Also known as: uniq



327
328
329
330
331
332
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 327

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)


299
300
301
302
303
304
305
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 299

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

#find(*args) ⇒ Object



78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 78

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

      result = find_by_scan(*args)

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

#first(*args) ⇒ Object



100
101
102
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 100

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

#ids_readerObject

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



46
47
48
49
50
51
52
53
54
55
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 46

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



58
59
60
61
62
63
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 58

def ids_writer(ids)
  pk_column = reflection.primary_key_column
  ids = Array(ids).reject { |id| id.blank? }
  ids.map! { |i| pk_column.type_cast(i) }
  replace(klass.find(ids).index_by { |r| r.id }.values_at(*ids))
end

#include?(record) ⇒ Boolean

Returns:

  • (Boolean)


348
349
350
351
352
353
354
355
356
357
358
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 348

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)
    end
  else
    false
  end
end

#last(*args) ⇒ Object



104
105
106
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 104

def last(*args)
  first_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.



287
288
289
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 287

def length
  load_target.size
end

#load_targetObject



360
361
362
363
364
365
366
367
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 360

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)


319
320
321
322
323
324
325
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 319

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

#null_scope?Boolean

Returns:

  • (Boolean)


391
392
393
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 391

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



30
31
32
33
34
35
36
37
38
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 30

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

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

#replace(other_array) ⇒ Object

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



337
338
339
340
341
342
343
344
345
346
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 337

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
    transaction { replace_records(other_array, original_target) }
  end
end

#resetObject



65
66
67
68
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 65

def reset
  super
  @target = []
end

#scope(opts = {}) ⇒ Object



385
386
387
388
389
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 385

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

#select(select = nil) ⇒ Object



70
71
72
73
74
75
76
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 70

def select(select = nil)
  if block_given?
    load_target.select.each { |e| yield e }
  else
    scope.select(select)
  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.



265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 265

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

#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


148
149
150
151
152
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 148

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



41
42
43
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 41

def writer(records)
  replace(records)
end