Class: ActiveRecord::Associations::CollectionAssociation
- Inherits:
-
Association
- Object
- Association
- ActiveRecord::Associations::CollectionAssociation
- 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
Instance Attribute Summary
Attributes inherited from Association
Instance Method Summary collapse
- #add_to_target(record, skip_callbacks = false, &block) ⇒ Object
- #build(attributes = nil, &block) ⇒ Object
-
#concat(*records) ⇒ Object
Add
records
to this association. -
#delete(*records) ⇒ Object
Removes
records
from this association callingbefore_remove
andafter_remove
callbacks. -
#delete_all(dependent = nil) ⇒ Object
Removes all records from the association without calling callbacks on the associated records.
-
#destroy(*records) ⇒ Object
Deletes the
records
and removes them from this association callingbefore_remove
,after_remove
,before_destroy
andafter_destroy
callbacks. -
#destroy_all ⇒ Object
Destroy all the records from this association.
-
#empty? ⇒ Boolean
Returns true if the collection is empty.
- #find(*args) ⇒ Object
- #find_from_target? ⇒ Boolean
-
#ids_reader ⇒ Object
Implements the ids reader method, e.g.
-
#ids_writer(ids) ⇒ Object
Implements the ids writer method, e.g.
- #include?(record) ⇒ Boolean
- #load_target ⇒ Object
- #null_scope? ⇒ Boolean
-
#reader ⇒ Object
Implements the reader method, e.g.
-
#replace(other_array) ⇒ Object
Replace this collection with
other_array
. - #reset ⇒ Object
- #scope ⇒ Object
-
#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. - #target=(record) ⇒ Object
-
#transaction(*args) ⇒ Object
Starts a transaction in the association class’s database connection.
-
#writer(records) ⇒ Object
Implements the writer method, e.g.
Methods inherited from Association
#create, #create!, #extensions, #initialize, #initialize_attributes, #inversed_from, #klass, #loaded!, #loaded?, #marshal_dump, #marshal_load, #reload, #remove_inverse_instance, #reset_negative_cache, #reset_scope, #scoping, #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, &block) ⇒ Object
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 281 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 |
#build(attributes = nil, &block) ⇒ Object
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 104 def build(attributes = nil, &block) if attributes.is_a?(Array) attributes.collect { |attr| build(attr, &block) } else add_to_target(build_record(attributes, &block)) end end |
#concat(*records) ⇒ Object
Add records
to this association. Since << flattens its argument list and inserts each record, push
and concat
behave identically.
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 114 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.
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 188 def delete(*records) 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.
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 152 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 |
#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.
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 197 def destroy(*records) delete_or_destroy(records, :destroy) end |
#destroy_all ⇒ Object
Destroy all the records from this association.
See destroy for more info.
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 174 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?
.
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 234 def empty? if loaded? || @association_ids || reflection.has_cached_counter? size.zero? else target.empty? && !scope.exists? end end |
#find(*args) ⇒ Object
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 81 def find(*args) if [:inverse_of] && loaded? args_flatten = args.flatten model = scope.klass 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_from_target? ⇒ Boolean
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 309 def find_from_target? loaded? || owner.new_record? || target.any? { |record| record.new_record? || record.changed? } end |
#ids_reader ⇒ Object
Implements the ids reader method, e.g. foo.item_ids for Foo.has_many :items
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 45 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
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 56 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
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 260 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_target ⇒ Object
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# 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 |
#null_scope? ⇒ Boolean
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 305 def null_scope? owner.new_record? && !foreign_key_present? end |
#reader ⇒ Object
Implements the reader method, e.g. foo.items for Foo.has_many :items
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 30 def reader 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.
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 244 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 |
#reset ⇒ Object
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 75 def reset super @target = [] @association_ids = nil end |
#scope ⇒ Object
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 299 def scope scope = super scope.none! if null_scope? scope 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.
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 211 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
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 288 def target=(record) return super unless ActiveRecord::Base.has_many_inversing case record when Array super else add_to_target(record, true) 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
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 133 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
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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 40 def writer(records) replace(records) end |