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 AssociationProxy.

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 collapse

Attributes inherited from Association

#owner, #reflection, #target

Instance Method Summary collapse

Methods inherited from Association

#aliased_table_name, #association_scope, #interpolate, #klass, #loaded!, #loaded?, #reload, #reset_scope, #scoped, #set_inverse_instance, #stale_target?, #target_scope

Constructor Details

#initialize(owner, reflection) ⇒ CollectionAssociation

Returns a new instance of CollectionAssociation



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 23

def initialize(owner, reflection)
  super
  @proxy = CollectionProxy.new(self)
end

Instance Attribute Details

#proxyObject (readonly)

:nodoc:



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 21

def proxy
  @proxy
end

Instance Method Details

#add_to_target(record) {|record| ... } ⇒ Object

Yields:

  • (record)


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 335

def add_to_target(record)
  callback(:before_add, record)
  yield(record) if block_given?

  if options[:uniq] && index = @target.index(record)
    @target[index] = record
  else
    @target << record
  end

  callback(:after_add, record)
  set_inverse_instance(record)

  record
end

#any?Boolean

Returns:

  • (Boolean)


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

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

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



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

def build(attributes = {}, options = {}, &block)
  if attributes.is_a?(Array)
    attributes.collect { |attr| build(attr, options, &block) }
  else
    add_to_target(build_record(attributes, options)) 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.



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

def concat(*records)
  result = true
  load_target if owner.new_record?

  transaction do
    records.flatten.each do |record|
      raise_on_type_mismatch(record)
      add_to_target(record) do |r|
        result &&= insert_record(record) unless owner.new_record?
      end
    end
  end

  result && records
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.



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 183

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
    if options[:uniq]
      # This is needed because 'SELECT count(DISTINCT *)..' is not valid SQL.
      column_name ||= reflection.klass.primary_key
      count_options.merge!(:distinct => true)
    end

    value = scoped.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 = {}, options = {}, &block) ⇒ Object



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

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

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



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

def create!(attributes = {}, options = {}, &block)
  create_record(attributes, options, 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.



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 219

def delete(*records)
  delete_or_destroy(records, options[:dependent])
end

#delete_allObject

Remove all records from this association

See delete for more info.



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 154

def delete_all
  delete(load_target).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.



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 228

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.



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# 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

Equivalent to collection.size.zero?. If the collection has not been already loaded and you are going to fetch the records anyway it is better to check collection.length.zero?.

Returns:

  • (Boolean)


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

def empty?
  size.zero?
end

#find(*args) ⇒ Object



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 80

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

#first(*args) ⇒ Object



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 92

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

#ids_readerObject

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? || 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}"

    scoped.select(column).except(:includes).map! do |record|
      record.send(reflection.association_primary_key)
    end
  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 60

def ids_writer(ids)
  pk_column = reflection.primary_key_column
  ids = Array.wrap(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)


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 313

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) : scoped.exists?(record)
    end
  else
    false
  end
end

#last(*args) ⇒ Object



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 96

def last(*args)
  first_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.



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 261

def length
  load_target.size
end

#load_targetObject



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 326

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)


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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 281

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

#reader(force_reload = false) ⇒ 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 29

def reader(force_reload = false)
  if force_reload
    klass.uncached { reload }
  elsif stale_target?
    reload
  end

  proxy
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 298

def replace(other_array)
  other_array.each { |val| raise_on_type_mismatch(val) }
  original_target = load_target.dup

  transaction do
    delete(target - other_array)

    unless concat(other_array - target)
      @target = original_target
      raise RecordNotSaved, "Failed to replace #{reflection.name} because one or more of the " \
                            "new records could not be saved."
    end
  end
end

#resetObject



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

def reset
  @loaded = false
  @target = []
end

#select(select = nil) ⇒ Object



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 72

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



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 243

def size
  if owner.new_record? || (loaded? && !options[:uniq])
    target.size
  elsif !loaded? && options[:group]
    load_target.size
  elsif !loaded? && !options[:uniq] && target.is_a?(Array)
    unsaved_records = target.select { |r| r.new_record? }
    unsaved_records.size + count_records
  else
    count_records
  end
end

#sum(*args) ⇒ Object

Calculate sum using SQL, not Enumerable



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# File 'activerecord/lib/active_record/associations/collection_association.rb', line 172

def sum(*args)
  if block_given?
    scoped.sum(*args) { |*block_args| yield(*block_args) }
  else
    scoped.sum(*args)
  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 145

def transaction(*args)
  reflection.klass.transaction(*args) do
    yield
  end
end

#uniq(collection = load_target) ⇒ Object



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

def uniq(collection = load_target)
  seen = {}
  collection.find_all do |record|
    seen[record.id] = true unless seen.key?(record.id)
  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