Class: ActiveRecord::Associations::CollectionAssociation

Inherits:
Association
  • Object
show all
Defined in:
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 



399
400
401
402
403
404
 
# File 'lib/active_record/associations/collection_association.rb', line 399

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) 


336
337
338
339
340
341
342
 
# File 'lib/active_record/associations/collection_association.rb', line 336

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

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



142
143
144
145
146
147
148
149
150
 
# File 'lib/active_record/associations/collection_association.rb', line 142

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.



163
164
165
166
167
168
169
170
 
# File 'lib/active_record/associations/collection_association.rb', line 163

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.



231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
 
# File 'lib/active_record/associations/collection_association.rb', line 231

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 



152
153
154
 
# File 'lib/active_record/associations/collection_association.rb', line 152

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

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



156
157
158
 
# File 'lib/active_record/associations/collection_association.rb', line 156

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.



262
263
264
265
266
267
268
269
 
# File 'lib/active_record/associations/collection_association.rb', line 262

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?(Fixnum) || 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.



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

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.



276
277
278
279
280
 
# File 'lib/active_record/associations/collection_association.rb', line 276

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

#destroy_all ⇒ Object

Destroy all the records from this association.

See destroy for more info.



222
223
224
225
226
227
 
# File 'lib/active_record/associations/collection_association.rb', line 222

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

#distinct ⇒ Object Also known as: uniq 



354
355
356
357
358
359
 
# File 'lib/active_record/associations/collection_association.rb', line 354

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) 


326
327
328
329
330
331
332
 
# File 'lib/active_record/associations/collection_association.rb', line 326

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

#fifth(*args) ⇒ Object 



120
121
122
 
# File 'lib/active_record/associations/collection_association.rb', line 120

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

#find(*args) ⇒ Object 



83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
 
# File 'lib/active_record/associations/collection_association.rb', line 83

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 



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

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

#forty_two(*args) ⇒ Object 



124
125
126
 
# File 'lib/active_record/associations/collection_association.rb', line 124

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

#fourth(*args) ⇒ Object 



116
117
118
 
# File 'lib/active_record/associations/collection_association.rb', line 116

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

#ids_reader ⇒ Object

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



51
52
53
54
55
56
57
58
59
60
 
# File '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



63
64
65
66
67
68
 
# File 'lib/active_record/associations/collection_association.rb', line 63

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

#include?(record) ⇒ Boolean

Returns:

  • (Boolean) 


378
379
380
381
382
383
384
385
386
387
388
 
# File 'lib/active_record/associations/collection_association.rb', line 378

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 



128
129
130
 
# File 'lib/active_record/associations/collection_association.rb', line 128

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

#length ⇒ Object

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.



314
315
316
 
# File 'lib/active_record/associations/collection_association.rb', line 314

def length
  load_target.size
end

#load_target ⇒ Object 



390
391
392
393
394
395
396
397
 
# File 'lib/active_record/associations/collection_association.rb', line 390

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) 


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

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

#null_scope? ⇒ Boolean

Returns:

  • (Boolean) 


428
429
430
 
# File 'lib/active_record/associations/collection_association.rb', line 428

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
 
# File '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.



364
365
366
367
368
369
370
371
372
373
374
375
376
 
# File 'lib/active_record/associations/collection_association.rb', line 364

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) 


406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
 
# File 'lib/active_record/associations/collection_association.rb', line 406

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

#reset ⇒ Object 



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

def reset
  super
  @target = []
end

#scope(opts = {}) ⇒ Object 



422
423
424
425
426
 
# File 'lib/active_record/associations/collection_association.rb', line 422

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

#second(*args) ⇒ Object 



108
109
110
 
# File 'lib/active_record/associations/collection_association.rb', line 108

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

#select(*fields) ⇒ Object 



75
76
77
78
79
80
81
 
# File 'lib/active_record/associations/collection_association.rb', line 75

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

#size ⇒ Object

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.



292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
 
# File 'lib/active_record/associations/collection_association.rb', line 292

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 



132
133
134
135
136
137
138
139
140
 
# File 'lib/active_record/associations/collection_association.rb', line 132

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 



112
113
114
 
# File 'lib/active_record/associations/collection_association.rb', line 112

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



181
182
183
184
185
 
# File 'lib/active_record/associations/collection_association.rb', line 181

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



46
47
48
 
# File 'lib/active_record/associations/collection_association.rb', line 46

def writer(records)
  replace(records)
end