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

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

Direct Known Subclasses

HasManyAssociation

Instance Attribute Summary

Attributes inherited from Association

#disable_joins, #owner, #reflection, #target

Instance Method Summary collapse

Methods inherited from Association

#create, #create!, #extensions, #initialize, #initialize_attributes, #inversed_from, #inversed_from_queries, #klass, #loaded!, #loaded?, #marshal_dump, #marshal_load, #reload, #remove_inverse_instance, #reset_negative_cache, #reset_scope, #set_inverse_instance, #set_inverse_instance_from_queries, #stale_target?

Constructor Details

This class inherits a constructor from ActiveRecord::Associations::Association

Instance Method Details

#add_to_target(record, skip_callbacks: false, replace: false, &block) ⇒ Object


271
272
273
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 271

def add_to_target(record, skip_callbacks: false, replace: false, &block)
  replace_on_target(record, skip_callbacks, replace: replace || association_scope.distinct_value, &block)
end

#build(attributes = nil, &block) ⇒ Object


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

def build(attributes = nil, &block)
  if attributes.is_a?(Array)
    attributes.collect { |attr| build(attr, &block) }
  else
    add_to_target(build_record(attributes, &block), replace: true)
  end
end

#concat(*records) ⇒ Object

Add records to this association. Since << flattens its argument list and inserts each record, push and concat behave identically.


119
120
121
122
123
124
125
126
127
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 119

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


178
179
180
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 178

def delete(*records)
  delete_or_destroy(records, options[: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.


142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 142

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.


187
188
189
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 187

def destroy(*records)
  delete_or_destroy(records, :destroy)
end

#destroy_allObject

Destroy all the records from this association.

See destroy for more info.


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

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

224
225
226
227
228
229
230
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 224

def empty?
  if loaded? || @association_ids || reflection.has_cached_counter?
    size.zero?
  else
    target.empty? && !scope.exists?
  end
end

#find(*args) ⇒ Object


86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 86

def find(*args)
  if options[:inverse_of] && loaded?
    args_flatten = args.flatten
    model = scope.klass

    if args_flatten.blank?
      error_message = "Couldn't find #{model.name} without an ID"
      raise RecordNotFound.new(error_message, model.name, model.primary_key, args)
    end

    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

#find_from_target?Boolean

Returns:

  • (Boolean)

298
299
300
301
302
303
304
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 298

def find_from_target?
  loaded? ||
    owner.strict_loading? ||
    reflection.strict_loading? ||
    owner.new_record? ||
    target.any? { |record| record.new_record? || record.changed? }
end

#ids_readerObject

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


49
50
51
52
53
54
55
56
57
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 49

def ids_reader
  if loaded?
    target.pluck(reflection.association_primary_key)
  elsif !target.empty?
    load_target.pluck(reflection.association_primary_key)
  else
    @association_ids ||= scope.pluck(reflection.association_primary_key)
  end
end

#ids_writer(ids) ⇒ Object

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


60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 60

def ids_writer(ids)
  primary_key = reflection.association_primary_key
  pk_type = klass.type_for_attribute(primary_key)
  ids = Array(ids).compact_blank
  ids.map! { |i| pk_type.cast(i) }

  records = klass.where(primary_key => ids).index_by do |r|
    r.public_send(primary_key)
  end.values_at(*ids).compact

  if records.size != ids.size
    found_ids = records.map { |record| record.public_send(primary_key) }
    not_found_ids = ids - found_ids
    klass.all.raise_record_not_found_exception!(ids, records.size, ids.size, primary_key, not_found_ids)
  else
    replace(records)
  end
end

#include?(record) ⇒ Boolean

Returns:

  • (Boolean)

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

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

#load_targetObject


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

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

  loaded!
  target
end

#null_scope?Boolean

Returns:

  • (Boolean)

294
295
296
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 294

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

#readerObject

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


32
33
34
35
36
37
38
39
40
41
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 32

def reader
  ensure_klass_exists!

  if stale_target?
    reload
  end

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

#replace(other_array) ⇒ Object

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


234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 234

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

#resetObject


79
80
81
82
83
84
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 79

def reset
  super
  @target = []
  @replaced_or_added_targets = Set.new
  @association_ids = nil
end

#scopeObject


288
289
290
291
292
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 288

def scope
  scope = super
  scope.none! if null_scope?
  scope
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.


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

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

#target=(record) ⇒ Object


275
276
277
278
279
280
281
282
283
284
285
286
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 275

def target=(record)
  return super unless reflection.klass.has_many_inversing

  case record
  when nil
    # It's not possible to remove the record from the inverse association.
  when Array
    super
  else
    replace_on_target(record, true, replace: true, inversing: true)
  end
end

#writer(records) ⇒ Object

Implements the writer method, e.g. foo.items= for Foo.has_many :items


44
45
46
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 44

def writer(records)
  replace(records)
end