diff options
Diffstat (limited to 'activerecord')
-rw-r--r-- | activerecord/CHANGELOG.md | 6 | ||||
-rw-r--r-- | activerecord/lib/active_record/attribute.rb | 6 | ||||
-rw-r--r-- | activerecord/lib/active_record/attribute_methods.rb | 33 | ||||
-rw-r--r-- | activerecord/lib/active_record/attribute_set.rb | 4 | ||||
-rw-r--r-- | activerecord/lib/active_record/attributes.rb | 2 | ||||
-rw-r--r-- | activerecord/test/cases/attribute_methods_test.rb | 10 | ||||
-rw-r--r-- | activerecord/test/cases/attribute_set_test.rb | 11 | ||||
-rw-r--r-- | activerecord/test/cases/attribute_test.rb | 19 | ||||
-rw-r--r-- | activerecord/test/cases/migration/references_foreign_key_test.rb | 4 | ||||
-rw-r--r-- | activerecord/test/cases/primary_keys_test.rb | 2 |
10 files changed, 92 insertions, 5 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index d5c141630e..45c3cb0690 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -1,3 +1,9 @@ +* Add `ActiveRecord::Base#accessed_fields`, which can be used to quickly + discover which fields were read from a model when you are looking to only + select the data you need from the database. + + *Sean Griffin* + * Introduce the `:if_exists` option for `drop_table`. Example: diff --git a/activerecord/lib/active_record/attribute.rb b/activerecord/lib/active_record/attribute.rb index 51e4fae62e..73bb059495 100644 --- a/activerecord/lib/active_record/attribute.rb +++ b/activerecord/lib/active_record/attribute.rb @@ -51,7 +51,7 @@ module ActiveRecord end def changed_in_place_from?(old_value) - type.changed_in_place?(old_value, value) + has_been_read? && type.changed_in_place?(old_value, value) end def with_value_from_user(value) @@ -78,6 +78,10 @@ module ActiveRecord false end + def has_been_read? + defined?(@value) + end + def ==(other) self.class == other.class && name == other.name && diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb index 8f165fb1dc..b2db0ceae7 100644 --- a/activerecord/lib/active_record/attribute_methods.rb +++ b/activerecord/lib/active_record/attribute_methods.rb @@ -369,6 +369,39 @@ module ActiveRecord write_attribute(attr_name, value) end + # Returns the name of all database fields which have been read from this + # model. This can be useful in devleopment mode to determine which fields + # need to be selected. For performance critical pages, selecting only the + # required fields can be an easy performance win (assuming you aren't using + # all of the fields on the model). + # + # For example: + # + # class PostsController < ActionController::Base + # after_action :print_accessed_fields, only: :index + # + # def index + # @posts = Post.all + # end + # + # private + # + # def print_accessed_fields + # p @posts.first.accessed_fields + # end + # end + # + # Which allows you to quickly change your code to: + # + # class PostsController < ActionController::Base + # def index + # @posts = Post.select(:id, :title, :author_id, :updated_at) + # end + # end + def accessed_fields + @attributes.accessed + end + protected def clone_attribute_value(reader_method, attribute_name) # :nodoc: diff --git a/activerecord/lib/active_record/attribute_set.rb b/activerecord/lib/active_record/attribute_set.rb index 66fcaf6945..fdce68ce45 100644 --- a/activerecord/lib/active_record/attribute_set.rb +++ b/activerecord/lib/active_record/attribute_set.rb @@ -64,6 +64,10 @@ module ActiveRecord end end + def accessed + attributes.select { |_, attr| attr.has_been_read? }.keys + end + protected attr_reader :attributes diff --git a/activerecord/lib/active_record/attributes.rb b/activerecord/lib/active_record/attributes.rb index b263a89d79..faf5d632ec 100644 --- a/activerecord/lib/active_record/attributes.rb +++ b/activerecord/lib/active_record/attributes.rb @@ -14,7 +14,7 @@ module ActiveRecord end module ClassMethods # :nodoc: - # Defines or overrides a attribute on this model. This allows customization of + # Defines or overrides an attribute on this model. This allows customization of # Active Record's type casting behavior, as well as adding support for user defined # types. # diff --git a/activerecord/test/cases/attribute_methods_test.rb b/activerecord/test/cases/attribute_methods_test.rb index 4036294121..ea2b94cbf4 100644 --- a/activerecord/test/cases/attribute_methods_test.rb +++ b/activerecord/test/cases/attribute_methods_test.rb @@ -937,6 +937,16 @@ class AttributeMethodsTest < ActiveRecord::TestCase assert model.id_came_from_user? end + def test_accessed_fields + model = @target.first + + assert_equal [], model.accessed_fields + + model.title + + assert_equal ["title"], model.accessed_fields + end + private def new_topic_like_ar_class(&block) diff --git a/activerecord/test/cases/attribute_set_test.rb b/activerecord/test/cases/attribute_set_test.rb index ba53612d30..8025c7c4d2 100644 --- a/activerecord/test/cases/attribute_set_test.rb +++ b/activerecord/test/cases/attribute_set_test.rb @@ -186,5 +186,16 @@ module ActiveRecord attributes.freeze assert_equal({ foo: "1" }, attributes.to_hash) end + + test "#accessed_attributes returns only attributes which have been read" do + builder = AttributeSet::Builder.new(foo: Type::Value.new, bar: Type::Value.new) + attributes = builder.build_from_database(foo: "1", bar: "2") + + assert_equal [], attributes.accessed + + attributes.fetch_value(:foo) + + assert_equal [:foo], attributes.accessed + end end end diff --git a/activerecord/test/cases/attribute_test.rb b/activerecord/test/cases/attribute_test.rb index 39a976fcc8..eac73e11e8 100644 --- a/activerecord/test/cases/attribute_test.rb +++ b/activerecord/test/cases/attribute_test.rb @@ -169,5 +169,24 @@ module ActiveRecord second = Attribute.from_user(:foo, 1, Type::Integer.new) assert_not_equal first, second end + + test "an attribute has not been read by default" do + attribute = Attribute.from_database(:foo, 1, Type::Value.new) + assert_not attribute.has_been_read? + end + + test "an attribute has been read when its value is calculated" do + attribute = Attribute.from_database(:foo, 1, Type::Value.new) + attribute.value + assert attribute.has_been_read? + end + + test "an attribute can not be mutated if it has not been read, + and skips expensive calculations" do + type_which_raises_from_all_methods = Object.new + attribute = Attribute.from_database(:foo, "bar", type_which_raises_from_all_methods) + + assert_not attribute.changed_in_place_from?("bar") + end end end diff --git a/activerecord/test/cases/migration/references_foreign_key_test.rb b/activerecord/test/cases/migration/references_foreign_key_test.rb index bba8897a0d..99de7db70c 100644 --- a/activerecord/test/cases/migration/references_foreign_key_test.rb +++ b/activerecord/test/cases/migration/references_foreign_key_test.rb @@ -10,8 +10,8 @@ module ActiveRecord end teardown do - @connection.execute("drop table if exists testings") - @connection.execute("drop table if exists testing_parents") + @connection.drop_table("testings") if @connection.table_exists? "testings" + @connection.drop_table("testing_parents") if @connection.table_exists? "testing_parents" end test "foreign keys can be created with the table" do diff --git a/activerecord/test/cases/primary_keys_test.rb b/activerecord/test/cases/primary_keys_test.rb index 751eccc015..4b668f84dd 100644 --- a/activerecord/test/cases/primary_keys_test.rb +++ b/activerecord/test/cases/primary_keys_test.rb @@ -210,7 +210,7 @@ class PrimaryKeyAnyTypeTest < ActiveRecord::TestCase end teardown do - @connection.execute("DROP TABLE IF EXISTS barcodes") + @connection.drop_table(:barcodes) if @connection.table_exists? :barcodes end def test_any_type_primary_key |