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 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

#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, #scoped, #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) 


371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
 
# File 'lib/active_record/associations/collection_association.rb', line 371

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) 


310
311
312
313
314
315
316
 
# File 'lib/active_record/associations/collection_association.rb', line 310

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

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



116
117
118
119
120
121
122
123
124
 
# File 'lib/active_record/associations/collection_association.rb', line 116

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.



137
138
139
140
141
142
143
144
145
 
# File 'lib/active_record/associations/collection_association.rb', line 137

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. If the :counter_sql or :finder_sql option is set for the association, it will be used for the query. Otherwise, construct options and pass them with scope to the target class’s count.



185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
 
# File 'lib/active_record/associations/collection_association.rb', line 185

def count(column_name = nil, count_options = {})
  column_name, count_options = nil, column_name if column_name.is_a?(Hash)

  if options[:counter_sql] || options[:finder_sql]
    unless count_options.blank?
      raise ArgumentError, "If finder_sql/counter_sql is used then options cannot be passed"
    end

    reflection.klass.count_by_sql(custom_counter_sql)
  else
    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, count_options)

    limit  = options[:limit]
    offset = options[:offset]

    if limit || offset
      [ [value - offset.to_i, 0].max, limit.to_i ].min
    else
      value
    end
  end
end

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



126
127
128
 
# File 'lib/active_record/associations/collection_association.rb', line 126

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

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



130
131
132
 
# File 'lib/active_record/associations/collection_association.rb', line 130

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.



222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
 
# File 'lib/active_record/associations/collection_association.rb', line 222

def delete(*records)
  dependent = options[:dependent]

  if records.first == :all

    if dependent && dependent == :destroy
      message = 'In Rails 4.1 delete_all on associations would not fire callbacks. ' \
                'It means if the :dependent option is :destroy then the associated ' \
                'records would be deleted without loading and invoking callbacks.'

      ActiveRecord::Base.logger ? ActiveRecord::Base.logger.warn(message) : $stderr.puts(message)
    end

    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 ⇒ Object

Remove all records from this association.

See delete for more info.



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

def delete_all
  delete(:all).tap do
    reset
    loaded!
  end
end

#destroy(*records) ⇒ Object

Destroy records and remove them from this association calling before_remove and after_remove callbacks.

Note that this method will always remove records from the database ignoring the :dependent option.



251
252
253
254
 
# File 'lib/active_record/associations/collection_association.rb', line 251

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_all ⇒ Object

Destroy all the records from this association.

See destroy for more info.



175
176
177
178
179
180
 
# File 'lib/active_record/associations/collection_association.rb', line 175

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

#distinct ⇒ Object Also known as: uniq 



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

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 or the :counter_sql option is provided, 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) 


300
301
302
303
304
305
306
 
# File 'lib/active_record/associations/collection_association.rb', line 300

def empty?
  if loaded? || options[:counter_sql]
    size.zero?
  else
    @target.blank? && !scope.exists?
  end
end

#find(*args) ⇒ Object 



84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
 
# File 'lib/active_record/associations/collection_association.rb', line 84

def find(*args)
  if block_given?
    load_target.find(*args) { |*block_args| yield(*block_args) }
  else
    if options[:finder_sql]
      find_by_scan(*args)
    elsif 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 



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

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

#ids_reader ⇒ Object

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



52
53
54
55
56
57
58
59
60
61
 
# File 'lib/active_record/associations/collection_association.rb', line 52

def ids_reader
  if loaded? || options[:finder_sql]
    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



64
65
66
67
68
69
 
# File 'lib/active_record/associations/collection_association.rb', line 64

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) 


349
350
351
352
353
354
355
356
357
358
359
360
 
# File 'lib/active_record/associations/collection_association.rb', line 349

def include?(record)
  if record.is_a?(reflection.klass)
    if record.new_record?
      include_in_memory?(record)
    else
      load_target if options[:finder_sql]
      loaded? ? target.include?(record) : scope.exists?(record)
    end
  else
    false
  end
end

#last(*args) ⇒ Object 



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

def last(*args)
  first_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.



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

def length
  load_target.size
end

#load_target ⇒ Object 



362
363
364
365
366
367
368
369
 
# File 'lib/active_record/associations/collection_association.rb', line 362

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) 


320
321
322
323
324
325
326
 
# File 'lib/active_record/associations/collection_association.rb', line 320

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

#null_scope? ⇒ Boolean

Returns:

  • (Boolean) 


393
394
395
 
# File 'lib/active_record/associations/collection_association.rb', line 393

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
39
40
41
42
43
44
 
# File '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

  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.new(klass, self)
  else
    @proxy ||= CollectionProxy.new(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.



338
339
340
341
342
343
344
345
346
347
 
# File 'lib/active_record/associations/collection_association.rb', line 338

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

#reset ⇒ Object 



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

def reset
  super
  @target = []
end

#scope(opts = {}) ⇒ Object 



387
388
389
390
391
 
# File 'lib/active_record/associations/collection_association.rb', line 387

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

#select(select = nil) ⇒ Object 



76
77
78
79
80
81
82
 
# File 'lib/active_record/associations/collection_association.rb', line 76

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



266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
 
# File 'lib/active_record/associations/collection_association.rb', line 266

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



156
157
158
159
160
 
# File 'lib/active_record/associations/collection_association.rb', line 156

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



47
48
49
 
# File 'lib/active_record/associations/collection_association.rb', line 47

def writer(records)
  replace(records)
end