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


423
424
425
426
427
428
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 423

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. If block given, loads all records and checks for one or more matches. Otherwise, equivalent to !collection.empty?.

Returns:

  • (Boolean)

357
358
359
360
361
362
363
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 357

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

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


165
166
167
168
169
170
171
172
173
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 165

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.


186
187
188
189
190
191
192
193
194
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 186

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

#count(column_name = nil) ⇒ Object

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


255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 255

def count(column_name = nil)
  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


175
176
177
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 175

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

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


179
180
181
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 179

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.


282
283
284
285
286
287
288
289
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 282

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.


224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 224

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.


296
297
298
299
300
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 296

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.


246
247
248
249
250
251
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 246

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

#distinctObject Also known as: uniq


376
377
378
379
380
381
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 376

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)

346
347
348
349
350
351
352
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 346

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

#fifth(*args) ⇒ Object


135
136
137
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 135

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

#find(*args) ⇒ Object


98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 98

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


119
120
121
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 119

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

#forty_two(*args) ⇒ Object


139
140
141
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 139

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

#fourth(*args) ⇒ Object


131
132
133
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 131

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


57
58
59
60
61
62
63
64
65
66
67
68
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 57

def ids_reader
  if loaded?
    load_target.map do |record|
      record.send(reflection.association_primary_key)
    end
  else
    @association_ids ||= (
      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


71
72
73
74
75
76
77
78
79
80
81
82
83
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 71

def ids_writer(ids)
  pk_type = reflection.association_primary_key_type
  ids = Array(ids).reject(&:blank?)
  ids.map! { |i| pk_type.cast(i) }
  records = klass.where(reflection.association_primary_key => ids).index_by do |r|
    r.send(reflection.association_primary_key)
  end.values_at(*ids).compact
  if records.size != ids.size
    klass.all.raise_record_not_found_exception!(ids, records.size, ids.size, reflection.association_primary_key)
  else
    replace(records)
  end
end

#include?(record) ⇒ Boolean

Returns:

  • (Boolean)

402
403
404
405
406
407
408
409
410
411
412
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 402

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


151
152
153
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 151

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.


334
335
336
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 334

def length
  load_target.size
end

#load_targetObject


414
415
416
417
418
419
420
421
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 414

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. If block given, loads all records and checks for two or more matches. Otherwise, equivalent to collection.size > 1.

Returns:

  • (Boolean)

368
369
370
371
372
373
374
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 368

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

#null_scope?Boolean

Returns:

  • (Boolean)

453
454
455
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 453

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


29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 29

def reader(force_reload = false)
  if force_reload
    ActiveSupport::Deprecation.warn(<<-MSG.squish)
      Passing an argument to force an association to reload is now
      deprecated and will be removed in Rails 5.1. Please call `reload`
      on the result collection proxy instead.
    MSG

    klass.uncached { reload }
  elsif stale_target?
    reload
  end

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


386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 386

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

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

Yields:

  • (record)

430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 430

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
    append_record(record)
  end

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

  record
end

#resetObject


85
86
87
88
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 85

def reset
  super
  @target = []
end

#scope(opts = {}) ⇒ Object


447
448
449
450
451
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 447

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

#second(*args) ⇒ Object


123
124
125
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 123

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

#second_to_last(*args) ⇒ Object


147
148
149
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 147

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

#select(*fields) ⇒ Object


90
91
92
93
94
95
96
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 90

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.


312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 312

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

#take(n = nil) ⇒ Object


155
156
157
158
159
160
161
162
163
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 155

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


127
128
129
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 127

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

#third_to_last(*args) ⇒ Object


143
144
145
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 143

def third_to_last(*args)
  first_nth_or_last(:third_to_last, *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

205
206
207
208
209
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 205

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


52
53
54
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 52

def writer(records)
  replace(records)
end