Class: ActiveRecord::Associations::CollectionAssociation
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Subclasses:
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Super Chains via Extension / Inclusion / Inheritance | |
Class Chain:
self,
Association
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Instance Chain:
self,
Association
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Inherits: |
ActiveRecord::Associations::Association
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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.
Class Method Summary
Association
- Inherited
Instance Attribute Summary
- #collection? ⇒ Boolean readonly
-
#empty? ⇒ Boolean
readonly
Returns true if the collection is empty.
- #find_from_target? ⇒ Boolean readonly
- #nested_attributes_target rw
- #null_scope? ⇒ Boolean readonly
- #target=(record) writeonly
Association
- Inherited
#collection? | Whether the association represent a single record or a collection of records. |
#disable_joins, | |
#loaded? | Has the target been already loaded? |
#options, #owner, #reflection, | |
#stale_target? | The target is stale if the target no longer points to the record(s) that the relevant foreign_key(s) refers to. |
#target, | |
#target= | Sets the target of this association to |
#find_target?, | |
#foreign_key_present? | Returns true if there is a foreign key present on the owner which references the target. |
#violates_strict_loading? |
Instance Method Summary
- #add_to_target(record, skip_callbacks: false, replace: false, &block)
- #build(attributes = nil, &block)
-
#concat(*records)
Add
records
to this association. -
#delete(*records)
Removes
records
from this association callingbefore_remove
andafter_remove
callbacks. -
#delete_all(dependent = nil)
Removes all records from the association without calling callbacks on the associated records.
-
#destroy(*records)
Deletes the
records
and removes them from this association callingbefore_remove
,after_remove
,before_destroy
andafter_destroy
callbacks. -
#destroy_all
Destroy all the records from this association.
- #find(*args)
-
#ids_reader
Implements the ids reader method, e.g.
-
#ids_writer(ids)
Implements the ids writer method, e.g.
- #include?(record) ⇒ Boolean
- #load_target
-
#reader
Implements the reader method, e.g.
-
#replace(other_array)
Replace this collection with
other_array
. - #reset
- #scope
-
#size
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. -
#writer(records)
Implements the writer method, e.g.
- #_create_record(attributes, raise = false, &block) private
- #callback(method, record) private
- #callbacks_for(callback_name) private
- #concat_records(records, raise = false) private
- #delete_or_destroy(records, method) private
-
#delete_records(records, method)
private
Delete the given records from the association, using one of the methods
:destroy
,:delete_all
or:nullify
(ornil
, in which case a default is used). -
#find_by_scan(*args)
private
If the
:inverse_of
option has been specified, then #find scans the entire collection. - #include_in_memory?(record) ⇒ Boolean private
-
#insert_record(record, validate = true, raise = false, &block)
private
Do the relevant stuff to insert the given record into the association collection.
-
#merge_target_lists(persisted, memory)
private
We have some records loaded from the database (persisted) and some that are in-memory (memory).
- #remove_records(existing_records, records, method) private
- #replace_common_records_in_memory(new_target, original_target) private
- #replace_on_target(record, skip_callbacks, replace:, inversing: false) private
- #replace_records(new_target, original_target) private
- #transaction(&block) private
Association
- Inherited
#async_load_target, #create, #create!, #extensions, #initialize_attributes, #inversed_from, #inversed_from_queries, | |
#klass | Returns the class of the target. |
#load_target | Loads the target if needed and returns it. |
#loaded! | Asserts the target has been loaded setting the loaded flag to |
#marshal_dump | We can’t dump @reflection and @through_reflection since it contains the scope proc. |
#marshal_load, | |
#reload | Reloads the target and returns |
#remove_inverse_instance | Remove the inverse association, if possible. |
#reset | Resets the loaded flag to |
#reset_negative_cache, #reset_scope, #scope, | |
#set_inverse_instance | Set the inverse association, if possible. |
#set_inverse_instance_from_queries, #set_strict_loading, | |
#association_scope | The scope for this association. |
#build_record, #enqueue_destroy_association, | |
#ensure_klass_exists! | Reader and writer methods call this so that consistent errors are presented when the association target class does not exist. |
#find_target, | |
#foreign_key_for? | Returns true if record contains the foreign_key. |
#inversable?, #inverse_association_for, | |
#inverse_reflection_for | Can be redefined by subclasses, notably polymorphic belongs_to The record parameter is necessary to support polymorphic inverses as we must check for the association in the specific class of the record. |
#invertible_for? | Returns true if inverse association on the given record needs to be set. |
#matches_foreign_key?, | |
#raise_on_type_mismatch! | Raises |
#scope_for_create, | |
#skip_statement_cache? | Returns true if statement cache should be skipped on the association reader. |
#skip_strict_loading, | |
#stale_state | This should be implemented to return the values of the relevant key(s) on the owner, so that when stale_state is different from the value stored on the last find_target, the target is stale. |
#target_scope | Can be overridden (i.e. in |
Constructor Details
This class inherits a constructor from ActiveRecord::Associations::Association
Instance Attribute Details
#collection? ⇒ Boolean
(readonly)
[ GitHub ]
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 316
def collection? true end
#empty? ⇒ Boolean
(readonly)
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?
.
#find_from_target? ⇒ Boolean
(readonly)
[ GitHub ]
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 308
def find_from_target? loaded? || (owner.strict_loading? && owner.strict_loading_all?) || reflection.strict_loading? || owner.new_record? || target.any? { |record| record.new_record? || record.changed? } end
#nested_attributes_target (rw)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 31
attr_accessor :nested_attributes_target
#null_scope? ⇒ Boolean
(readonly)
[ GitHub ]
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 304
def null_scope? owner.new_record? && !foreign_key_present? end
#target=(record) (writeonly)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 285
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
Instance Method Details
#_create_record(attributes, raise = false, &block) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 354
def _create_record(attributes, raise = false, &block) unless owner.persisted? raise ActiveRecord::RecordNotSaved.new("You cannot call create unless the parent is saved", owner) end if attributes.is_a?(Array) attributes.collect { |attr| _create_record(attr, raise, &block) } else record = build_record(attributes, &block) transaction do result = nil add_to_target(record) do result = insert_record(record, true, raise) { @_was_loaded = loaded? } end raise ActiveRecord::Rollback unless result end record end end
#add_to_target(record, skip_callbacks: false, replace: false, &block)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 281
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)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 117
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
#callback(method, record) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 492
def callback(method, record) callbacks_for(method).each do |callback| callback.call(method, owner, record) end end
#callbacks_for(callback_name) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 498
def callbacks_for(callback_name) full_callback_name = "#{callback_name}_for_#{reflection.name}" if owner.class.respond_to?(full_callback_name) owner.class.send(full_callback_name) else [] end end
#concat(*records)
Add records
to this association. Since <<
flattens its argument list and inserts each record, push
and concat
behave identically.
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 127
def concat(*records) records = records.flatten if owner.new_record? skip_strict_loading { load_target } concat_records(records) else transaction { concat_records(records) } end end
#concat_records(records, raise = false) (private)
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 438
def concat_records(records, raise = false) result = true records.each do |record| raise_on_type_mismatch!(record) add_to_target(record) do unless owner.new_record? result &&= insert_record(record, true, raise) { @_was_loaded = loaded? } end end end raise ActiveRecord::Rollback unless result records end
#delete(*records)
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.
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 186
def delete(*records) delete_or_destroy(records, [:dependent]) end
#delete_all(dependent = nil)
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.
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 150
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 [:dependent] == :destroy :delete_all else [:dependent] end delete_or_nullify_all_records(dependent).tap do reset loaded! end end
#delete_or_destroy(records, method) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 385
def delete_or_destroy(records, method) return if records.empty? records = find(records) if records.any? { |record| record.kind_of?(Integer) || record.kind_of?(String) } records = records.flatten records.each { |record| raise_on_type_mismatch!(record) } existing_records = records.reject(&:new_record?) if existing_records.empty? remove_records(existing_records, records, method) else transaction { remove_records(existing_records, records, method) } end end
#delete_records(records, method) (private)
Delete the given records from the association, using one of the methods :destroy
, :delete_all
or :nullify
(or nil
, in which case a default is used).
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 414
def delete_records(records, method) raise NotImplementedError end
#destroy(*records)
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.
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 195
def destroy(*records) delete_or_destroy(records, :destroy) end
#destroy_all
Destroy all the records from this association.
See destroy for more info.
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 172
def destroy_all destroy(load_target).tap do reset loaded! end end
#find(*args)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 94
def find(*args) if [:inverse_of] && loaded? args_flatten = args.flatten model = scope.model if args_flatten.blank? = "Couldn't find #{model.name} without an ID" raise RecordNotFound.new(, 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_by_scan(*args) (private)
If the :inverse_of
option has been specified, then #find scans the entire collection.
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 521
def find_by_scan(*args) expects_array = args.first.kind_of?(Array) ids = args.flatten.compact.map(&:to_s).uniq if ids.size == 1 id = ids.first record = load_target.detect { |r| id == r.id.to_s } expects_array ? [ record ] : record else load_target.select { |r| ids.include?(r.id.to_s) } end end
#ids_reader
Implements the ids reader method, e.g. foo.item_ids for Foo.has_many
:items
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 51
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)
Implements the ids writer method, e.g. foo.item_ids= for Foo.has_many
:items
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 62
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! { |id| pk_type.cast(id) } records = if klass.composite_primary_key? klass.where(primary_key => ids).index_by do |record| primary_key.map { |primary_key| record._read_attribute(primary_key) } end else klass.where(primary_key => ids).index_by do |record| record._read_attribute(primary_key) end end.values_at(*ids).compact if records.size != ids.size found_ids = records.map { |record| record._read_attribute(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
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 258
def include?(record) klass = reflection.klass return false unless record.is_a?(klass) if record.new_record? include_in_memory?(record) elsif loaded? target.include?(record) else record_id = klass.composite_primary_key? ? klass.primary_key.zip(record.id).to_h : record.id scope.exists?(record_id) end end
#include_in_memory?(record) ⇒ Boolean
(private)
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 507
def include_in_memory?(record) if reflection.is_a?(ActiveRecord::Reflection::ThroughReflection) assoc = owner.association(reflection.through_reflection.name) assoc.reader.any? { |source| target_reflection = source.send(reflection.source_reflection.name) target_reflection.respond_to?(:include?) ? target_reflection.include?(record) : target_reflection == record } || target.include?(record) else target.include?(record) end end
#insert_record(record, validate = true, raise = false, &block) (private)
Do the relevant stuff to insert the given record into the association collection.
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 377
def insert_record(record, validate = true, raise = false, &block) if raise record.save!(validate: validate, &block) else record.save(validate: validate, &block) end end
#load_target
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 272
def load_target if find_target? @target = merge_target_lists(find_target, target) end loaded! target end
#merge_target_lists(persisted, memory) (private)
We have some records loaded from the database (persisted) and some that are in-memory (memory). The same record may be represented in the persisted array and in the memory array.
So the task of this method is to merge them according to the following rules:
* The final array must not have duplicates
* The order of the persisted array is to be preserved
* Any changes made to attributes on objects in the memory array are to be preserved
* Otherwise, attributes should have the value found in the database
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 335
def merge_target_lists(persisted, memory) return persisted if memory.empty? persisted.map! do |record| if mem_record = memory.delete(record) ((record.attribute_names & mem_record.attribute_names) - mem_record.changed_attribute_names_to_save - mem_record.class._attr_readonly).each do |name| mem_record._write_attribute(name, record[name]) end mem_record else record end end persisted + memory.reject(&:persisted?) end
#reader
Implements the reader method, e.g. foo.items for Foo.has_many
:items
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 34
def reader ensure_klass_exists! if stale_target? reload end @proxy ||= CollectionProxy.create(klass, self) @proxy.reset_scope end
#remove_records(existing_records, records, method) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 399
def remove_records(existing_records, records, method) catch(:abort) do records.each { |record| callback(:before_remove, record) } end || return delete_records(existing_records, method) if existing_records.any? @target -= records @association_ids = nil records.each { |record| callback(:after_remove, record) } end
#replace(other_array)
Replace this collection with other_array
. This will perform a diff and delete/add only records that have changed.
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 242
def replace(other_array) other_array.each { |val| raise_on_type_mismatch!(val) } original_target = skip_strict_loading { 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_common_records_in_memory(new_target, original_target) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 430
def replace_common_records_in_memory(new_target, original_target) common_records = intersection(new_target, original_target) common_records.each do |record| skip_callbacks = true replace_on_target(record, skip_callbacks, replace: true) end end
#replace_on_target(record, skip_callbacks, replace:, inversing: false) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 457
def replace_on_target(record, skip_callbacks, replace:, inversing: false) if replace && (!record.new_record? || @replaced_or_added_targets.include?(record)) index = @target.index(record) end catch(:abort) do callback(:before_add, record) end || return unless skip_callbacks set_inverse_instance(record) @_was_loaded = true yield(record) if block_given? if !index && @replaced_or_added_targets.include?(record) index = @target.index(record) end @replaced_or_added_targets << record if inversing || index || record.new_record? if index target[index] = record elsif @_was_loaded || !loaded? @association_ids = nil target << record end callback(:after_add, record) unless skip_callbacks record ensure @_was_loaded = nil end
#replace_records(new_target, original_target) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 418
def replace_records(new_target, original_target) delete(difference(target, new_target)) unless concat(difference(new_target, target)) @target = original_target raise RecordNotSaved, "Failed to replace #{reflection.name} because one or more of the " \ "new records could not be saved." end target end
#reset
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 87
def reset super @target = [] @replaced_or_added_targets = Set.new.compare_by_identity @association_ids = nil end
#scope
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 298
def scope scope = super scope.none! if null_scope? scope end
#size
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.
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 209
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
#transaction(&block) (private)
[ GitHub ]# File 'activerecord/lib/active_record/associations/collection_association.rb', line 321
def transaction(&block) reflection.klass.transaction(&block) end
#writer(records)
Implements the writer method, e.g. foo.items= for Foo.has_many
:items
# File 'activerecord/lib/active_record/associations/collection_association.rb', line 46
def writer(records) replace(records) end