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Simplify/fix implementation of default scopes

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The previous implementation was necessary in order to support stuff
like:

    class Post < ActiveRecord::Base
      default_scope where(published: true)
      scope :ordered, order("created_at")
    end

If we didn't evaluate the default scope at the last possible moment
before sending the SQL to the database, it would become impossible to
do:

    Post.unscoped.ordered

This is because the default scope would already be bound up in the
"ordered" scope, and therefore wouldn't be removed by the
"Post.unscoped" part.

In 4.0, we have deprecated all "eager" forms of scopes. So now you must
write:

    class Post < ActiveRecord::Base
      default_scope { where(published: true) }
      scope :ordered, -> { order("created_at") }
    end

This prevents the default scope getting bound up inside the "ordered"
scope, which means we can now have a simpler/better/more natural
implementation of default scoping.

A knock on effect is that some things that didn't work properly now do.
For example it was previously impossible to use #except to remove a part
of the default scope, since the default scope was evaluated after the
call to #except.
This commit is contained in:
Jon Leighton 2013-06-28 13:32:54 +01:00
parent e66c148571
commit 94924dc32b
12 changed files with 31 additions and 74 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
activerecord/lib/active_record/associations/association.rb
View file

@ -122,11 +122,7 @@ module ActiveRecord
# Can be overridden (i.e. in ThroughAssociation) to merge in other scopes (i.e. the
# through association's scope)
def target_scope
all = klass.all
scope = AssociationRelation.new(klass, klass.arel_table, self)
scope.merge! all
scope.default_scoped = all.default_scoped?
scope
AssociationRelation.new(klass, klass.arel_table, self).merge!(klass.all)
end
# Loads the \target if needed and returns it.

1
activerecord/lib/active_record/associations/collection_proxy.rb
View file

@ -33,7 +33,6 @@ module ActiveRecord
def initialize(klass, association) #:nodoc:
@association = association
super klass, klass.arel_table
self.default_scoped = true
merge! association.scope(nullify: false)
end

3
activerecord/lib/active_record/associations/preloader/association.rb
View file

@ -98,7 +98,6 @@ module ActiveRecord
def build_scope
scope = klass.unscoped
scope.default_scoped = true
values = reflection_scope.values
preload_values = preload_scope.values
@ -113,7 +112,7 @@ module ActiveRecord
scope.where!(klass.table_name => { reflection.type => model.base_class.sti_name })
end
scope
klass.default_scoped.merge(scope)
end
end
end

2
activerecord/lib/active_record/associations/through_association.rb
View file

@ -15,7 +15,7 @@ module ActiveRecord
scope = super
chain[1..-1].each do |reflection|
scope.merge!(
reflection.klass.all.with_default_scope.
reflection.klass.all.
except(:select, :create_with, :includes, :preload, :joins, :eager_load)
)
end

50
activerecord/lib/active_record/relation.rb
View file

@ -17,17 +17,14 @@ module ActiveRecord
include FinderMethods, Calculations, SpawnMethods, QueryMethods, Batches, Explain, Delegation
attr_reader :table, :klass, :loaded
attr_accessor :default_scoped
alias :model :klass
alias :loaded? :loaded
alias :default_scoped? :default_scoped
def initialize(klass, table, values = {})
@klass = klass
@table = table
@values = values
@loaded = false
@default_scoped = false
@klass = klass
@table = table
@values = values
@loaded = false
end
def initialize_copy(other)
@ -313,7 +310,7 @@ module ActiveRecord
stmt.table(table)
stmt.key = table[primary_key]
if with_default_scope.joins_values.any?
if joins_values.any?
@klass.connection.join_to_update(stmt, arel)
else
stmt.take(arel.limit)
@ -438,7 +435,7 @@ module ActiveRecord
stmt = Arel::DeleteManager.new(arel.engine)
stmt.from(table)
if with_default_scope.joins_values.any?
if joins_values.any?
@klass.connection.join_to_delete(stmt, arel, table[primary_key])
else
stmt.wheres = arel.constraints
@ -512,12 +509,11 @@ module ActiveRecord
# User.where(name: 'Oscar').where_values_hash
# # => {name: "Oscar"}
def where_values_hash
scope = with_default_scope
equalities = scope.where_values.grep(Arel::Nodes::Equality).find_all { |node|
equalities = where_values.grep(Arel::Nodes::Equality).find_all { |node|
node.left.relation.name == table_name
}
binds = Hash[scope.bind_values.find_all(&:first).map { |column, v| [column.name, v] }]
binds = Hash[bind_values.find_all(&:first).map { |column, v| [column.name, v] }]
binds.merge!(Hash[bind_values.find_all(&:first).map { |column, v| [column.name, v] }])
Hash[equalities.map { |where|
@ -565,16 +561,6 @@ module ActiveRecord
q.pp(self.to_a)
end
def with_default_scope #:nodoc:
if default_scoped? && default_scope = klass.send(:build_default_scope)
default_scope = default_scope.merge(self)
default_scope.default_scoped = false
default_scope
else
self
end
end
# Returns true if relation is blank.
def blank?
to_a.blank?
@ -594,22 +580,16 @@ module ActiveRecord
private
def exec_queries
default_scoped = with_default_scope
@records = eager_loading? ? find_with_associations : @klass.find_by_sql(arel, bind_values)
if default_scoped.equal?(self)
@records = eager_loading? ? find_with_associations : @klass.find_by_sql(arel, bind_values)
preload = preload_values
preload += includes_values unless eager_loading?
preload.each do |associations|
ActiveRecord::Associations::Preloader.new(@records, associations).run
end
@records.each { |record| record.readonly! } if readonly_value
else
@records = default_scoped.to_a
preload = preload_values
preload += includes_values unless eager_loading?
preload.each do |associations|
ActiveRecord::Associations::Preloader.new(@records, associations).run
end
@records.each { |record| record.readonly! } if readonly_value
@loaded = true
@records
end

12
activerecord/lib/active_record/relation/calculations.rb
View file

@ -91,20 +91,14 @@ module ActiveRecord
#
# Person.sum("2 * age")
def calculate(operation, column_name, options = {})
relation = with_default_scope
if column_name.is_a?(Symbol) && attribute_aliases.key?(column_name.to_s)
column_name = attribute_aliases[column_name.to_s].to_sym
end
if relation.equal?(self)
if has_include?(column_name)
construct_relation_for_association_calculations.calculate(operation, column_name, options)
else
perform_calculation(operation, column_name, options)
end
if has_include?(column_name)
construct_relation_for_association_calculations.calculate(operation, column_name, options)
else
relation.calculate(operation, column_name, options)
perform_calculation(operation, column_name, options)
end
end

3
activerecord/lib/active_record/relation/finder_methods.rb
View file

@ -211,7 +211,6 @@ module ActiveRecord
relation = relation.where(table[primary_key].eq(conditions)) if conditions != :none
end
relation = relation.with_default_scope
connection.select_value(relation.arel, "#{name} Exists", relation.bind_values)
end
@ -354,7 +353,7 @@ module ActiveRecord
if loaded?
@records.first
else
@first ||= find_first_with_limit(with_default_scope.order_values, 1).first
@first ||= find_first_with_limit(order_values, 1).first
end
end

4
activerecord/lib/active_record/relation/merger.rb
View file

@ -42,10 +42,6 @@ module ActiveRecord
attr_reader :relation, :values, :other
def initialize(relation, other)
if other.default_scoped? && other.klass != relation.klass
other = other.with_default_scope
end
@relation = relation
@values = other.values
@other = other

2
activerecord/lib/active_record/relation/query_methods.rb
View file

@ -795,7 +795,7 @@ module ActiveRecord
# Returns the Arel object associated with the relation.
def arel
@arel ||= with_default_scope.build_arel
@arel ||= build_arel
end
# Like #arel, but ignores the default scope of the model.

1
activerecord/lib/active_record/relation/spawn_methods.rb
View file

@ -65,7 +65,6 @@ module ActiveRecord
def relation_with(values) # :nodoc:
result = Relation.new(klass, table, values)
result.default_scoped = default_scoped
result.extend(*extending_values) if extending_values.any?
result
end

16
activerecord/lib/active_record/scoping/named.rb
View file

@ -25,22 +25,18 @@ module ActiveRecord
if current_scope
current_scope.clone
else
scope = relation
scope.default_scoped = true
scope
default_scoped
end
end
def default_scoped # :nodoc:
relation.merge(build_default_scope)
end
# Collects attributes from scopes that should be applied when creating
# an AR instance for the particular class this is called on.
def scope_attributes # :nodoc:
if current_scope
current_scope.scope_for_create
else
scope = relation
scope.default_scoped = true
scope.scope_for_create
end
all.scope_for_create
end
# Are there default attributes associated with this scope?

5
activerecord/test/cases/scoping/default_scoping_test.rb
View file

@ -153,9 +153,8 @@ class DefaultScopingTest < ActiveRecord::TestCase
end
def test_order_to_unscope_reordering
expected = DeveloperOrderedBySalary.all.collect { |dev| [dev.name, dev.id] }
received = DeveloperOrderedBySalary.order('salary DESC, name ASC').reverse_order.unscope(:order).collect { |dev| [dev.name, dev.id] }
assert_equal expected, received
scope = DeveloperOrderedBySalary.order('salary DESC, name ASC').reverse_order.unscope(:order)
assert !(scope.to_sql =~ /order/i)
end
def test_unscope_reverse_order