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) {|record| ... } ⇒ Object

Yields:

  • (record)


387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 387

def add_to_target(record, skip_callbacks = false)
  callback(:before_add, record) unless skip_callbacks
  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) unless skip_callbacks
  set_inverse_instance(record)

  record
end

#any?Boolean

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

Returns:

  • (Boolean)


327
328
329
330
331
332
333
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 327

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

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



126
127
128
129
130
131
132
133
134
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 126

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.



147
148
149
150
151
152
153
154
155
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 147

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.



216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 216

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



136
137
138
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 136

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

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



140
141
142
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 140

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.



247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 247

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

  if records.first == :all
    if (loaded? || dependent == :destroy) && dependent != :delete_all
      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 `: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.



185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 185

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
                :delete_all
              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.



268
269
270
271
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 268

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.



207
208
209
210
211
212
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 207

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

#distinctObject Also known as: uniq



345
346
347
348
349
350
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 345

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)


317
318
319
320
321
322
323
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 317

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

#fifth(*args) ⇒ Object



114
115
116
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 114

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

#find(*args) ⇒ Object



77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 77

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



98
99
100
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 98

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

#forty_two(*args) ⇒ Object



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

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

#fourth(*args) ⇒ Object



110
111
112
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 110

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



45
46
47
48
49
50
51
52
53
54
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 45

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



57
58
59
60
61
62
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 57

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)


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

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



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

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.



305
306
307
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 305

def length
  load_target.size
end

#load_targetObject



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

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)


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

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

#null_scope?Boolean

Returns:

  • (Boolean)


409
410
411
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 409

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
# 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

  @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.



355
356
357
358
359
360
361
362
363
364
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 355

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



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

def reset
  super
  @target = []
end

#scope(opts = {}) ⇒ Object



403
404
405
406
407
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 403

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

#second(*args) ⇒ Object



102
103
104
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 102

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

#select(*fields) ⇒ Object



69
70
71
72
73
74
75
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 69

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.



283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 283

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

#third(*args) ⇒ Object



106
107
108
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 106

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


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

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



40
41
42
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 40

def writer(records)
  replace(records)
end