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Active Record
is still
Magical
Neeraj Singh
Saturday, October 12, 13
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$ bundle exec rake test_sqlite3
3684 runs, 10491 assertions, 0 failures,
0 errors, 29 skips
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# make sure we get the gem, not stdlib
gem 'minitest'
require 'minitest'
# active_support/test_case.rb
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# Returns all instance methods starting with "test_".
# Based on test_order, the methods are either sorted,
# randomized(default), or run in parallel.
def self.runnable_methods
methods = methods_matching(/^test_/)
case self.test_order
when :parallel
max = methods.size
ParallelEach.new methods.sort.sort_by { rand max }
when :random then
max = methods.size
methods.sort.sort_by { rand max }
when :alpha, :sorted then
methods.sort
else
raise "Unknown test_order:
#{self.test_order.inspect}"
end
end
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# Defines the order to run tests
# (:random by default). Override
# this or use a convenience method to change it
# for your tests.
def self.test_order
:random
end
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module Minitest # :nodoc:
def self.__run reporter, options # :nodoc:
# FIXME: MT5's runnables is not ordered. This is
# needed because
# we have have tests have cross-class order-
dependent bugs.
suites = Runnable.runnables.sort_by { |ts|
ts.name.to_s }
parallel, serial = suites.partition { |s|
s.test_order == :parallel }
ParallelEach.new(parallel).map { |suite| suite.run
reporter, options } +
serial.map { |suite| suite.run reporter, options }
end
end
# active_support/test_case.rb
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# FIXME: MT5's runnables is not ordered.
# This is needed because
# we have have tests have cross-class
# order-dependent bugs.
suites = Runnable.runnables.sort_by { |ts|
ts.name.to_s }
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module Minitest # :nodoc:
def self.__run reporter, options # :nodoc:
# FIXME: MT5's runnables is not ordered. This is
# needed because
# we have have tests have cross-class order-
dependent bugs.
suites = Runnable.runnables.sort_by { |ts|
ts.name.to_s }
suites.each { |s| puts s }
parallel, serial = suites.partition { |s|
s.test_order == :parallel }
ParallelEach.new(parallel).map { |suite| suite.run
reporter, options } +
serial.map { |suite| suite.run reporter, options }
end
end
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CalculationsTest
CallbacksOnMultipleActionsTest
CallbacksTest
CascadedEagerLoadingTest
CheckEscapedYamlFixturesTest
CheckSetTableNameFixturesTest
CopyMigrationsTest
CopyTableTest
CoreTest
CounterCacheTest
CustomConnectionFixturesTest
CustomNameForFixtureOrModelTest
DatabaseConnectedJsonEncodingTest
DatabaseConnectedXmlSerializationTest
DatabaseStatementsTest
DateTimeTest
DefaultScopingTest
DefaultStringsTest
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Finished in 373.451968s, 9.8647 runs/s,
28.0920 assertions/s.
3684 runs, 10491 assertions, 0 failures,
0 errors, 29 skips
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Runnable.runnables.sort_by { |t| t.name.to_s }
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Runnable.runnables.sort_by { |t| t.name.to_s }
Runnable.runnables.sort_by { |t| t.name.to_s.reverse }
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3684 runs, 10446 assertions, 8 failures,
5 errors, 29 skips
sqlite3
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3924 runs, 11064 assertions,
25 failures, 41 errors, 22 skips
postgresql
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3684 runs, 10534 assertions, 8 failures,
4 errors, 23 skips
mysql2
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Help Active Record
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“Any sufficiently
advanced technology is
indistinguishable from magic.”
― Arthur C. Clarke,
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irb(main):> User.where id: '45'
SELECT "users".* FROM "users"
WHERE "users"."id" = 45
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irb(main):> User.where id: '45'
SELECT "users".* FROM "users"
WHERE "users"."id" = 45
irb(main):> User.where name: 10
SELECT "users".* FROM "users"
WHERE "users"."name" = 10
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class Physician < ActiveRecord::Base
has_many :appointments
has_many :patients, through: :appointments
end
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class Physician < ActiveRecord::Base
has_many :appointments
has_many :patients, through: :appointments
end
irb(main):> physician.appointments.create!
INSERT INTO "appointments" ("physician_id") VALUES ($1)
RETURNING "id" [["physician_id", 1]]
=> #
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class Physician < ActiveRecord::Base
has_many :appointments
has_many :patients, through: :appointments
end
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class Physician < ActiveRecord::Base
has_many :appointments
has_many :patients, through: :appointments
end
irb(main):> physician.patients.create!
INSERT INTO "patients" DEFAULT VALUES RETURNING "id"
INSERT INTO "appointments" ("patient_id",
"physician_id") VALUES ($1, $2)
RETURNING "id" [["patient_id", 2], ["physician_id",
1]]
=> #
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class Physician < ActiveRecord::Base
has_many :appointments
has_many :patients, through: :appointments
end
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class Physician < ActiveRecord::Base
has_many :appointments
has_many :patients, through: :appointments
end
irb(main):> physician.patients.where(id: 50).create!
INSERT INTO "patients" ("id") VALUES ($1) RETURNING
"id" [["id", 50]]
=> #
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irb(main):> physician.patients.where(id: 50).class.name
=> "ActiveRecord::AssociationRelation"
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irb(main):> physician.patients.class.name
=> "ActiveRecord::Associations::CollectionProxy"
irb(main):> physician.patients.where(id: 50).class.name
=> "ActiveRecord::AssociationRelation"
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irb(main):> Physician.all.class.name
=> "ActiveRecord::Relation"
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irb(main):> Physician.all
.where(id: 2)
.where(name: 'John')
.class.name
=> "ActiveRecord::Relation"
irb(main):> Physician.all.class.name
=> "ActiveRecord::Relation"
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class CollectionProxy < Relation
end
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A collectionProxy has reference to the association it
is acting on
class CollectionProxy < Relation
end
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A collectionProxy has reference to the association it
is acting on
class CollectionProxy < Relation
end
irb(main):> Physician.last
.patients
.instance_variable_get(:@association)
.class
=>
ActiveRecord::Associations::HasManyThroughAssociation
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irb(main):> physician.patients.where(id: 50).create!
INSERT INTO "patients" ("id") VALUES ($1) RETURNING
"id" [["id", 50]]
=> #
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def create(*args, &block)
scoping { @klass.create(*args, &block) }
end
irb(main):> physician.patients.where(id: 50).create!
INSERT INTO "patients" ("id") VALUES ($1) RETURNING
"id" [["id", 50]]
=> #
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def create!(attributes = {}, &block)
@association.create!(attributes, &block)
end
def create(*args, &block)
scoping { @klass.create(*args, &block) }
end
irb(main):> physician.patients.where(id: 50).create!
INSERT INTO "patients" ("id") VALUES ($1) RETURNING
"id" [["id", 50]]
=> #
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class Car < ActiveRecord::Base
scope :good, where(:id => 1)
scope :bad, where(:id => 2)
end
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class Car < ActiveRecord::Base
scope :good, where(:id => 1)
scope :bad, where(:id => 2)
end
# using scopes
Car.good.bad
SELECT "cars".* FROM "cars" WHERE "cars"."id" = 2
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class Car < ActiveRecord::Base
scope :good, where(:id => 1)
scope :bad, where(:id => 2)
end
# using scopes
Car.good.bad
SELECT "cars".* FROM "cars" WHERE "cars"."id" = 2
# using scopes
Car.bad.good
SELECT "cars".* FROM "cars" WHERE "cars"."id" = 1
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class Car < ActiveRecord::Base
scope :good, where(:id => 1)
scope :bad, where(:id => 2)
end
# using scopes
Car.good.bad
SELECT "cars".* FROM "cars" WHERE "cars"."id" = 2
# using wheres
Car.where(:id => 1).where(:id => 2)
SELECT "cars".* FROM "cars" WHERE "cars"."id" = 1
AND "cars"."id" = 2
# using scopes
Car.bad.good
SELECT "cars".* FROM "cars" WHERE "cars"."id" = 1
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class User < ActiveRecord::Base
end
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class User < ActiveRecord::Base
end
irb(main):> User.where(name: 'john')
.order('id desc')
.except(:order)
=> SELECT "users".* FROM "users"
WHERE "users"."name" = 'john'
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class User < ActiveRecord::Base
default_scope { where(active: true) }
end
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class User < ActiveRecord::Base
default_scope { where(active: true) }
end
irb(main):> User.where(name: 'john')
.order('id desc')
.except(:order)
=> SELECT "users".* FROM "users"
WHERE "users"."active" = 't'
AND "users"."name" = 'john'
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class User < ActiveRecord::Base
default_scope { where(active: true) }
end
irb(main):> User.where(name: 'john')
.order('id desc')
.except(:order)
=> SELECT "users".* FROM "users"
WHERE "users"."active" = 't'
AND "users"."name" = 'john'
irb(main):> User.order('id desc')
.except(:where)
=> SELECT "users".* FROM "users"
ORDER BY id desc
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class User < ActiveRecord::Base
default_scope { where(active: true) }
scope :signed_in_2013, -> {
except(:where)
.where(created_at: Time.now.all_year) }
end
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class User < ActiveRecord::Base
default_scope { where(active: true) }
scope :signed_in_2013, -> {
except(:where)
.where(created_at: Time.now.all_year) }
end
irb(main):> User.signed_in_2013
=> SELECT "users".* FROM "users"
WHERE "users"."active" = 't'
AND ("users"."created_at"
BETWEEN '2013-01-01 05:00:00.000000'
AND '2014-01-01
04:59:59.999999')
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class User < ActiveRecord::Base
default_scope { where(active: true) }
scope :signed_in_2013, -> {
except(:where)
.where(created_at: Time.now.all_year) }
end
irb(main):> User.signed_in_2013
=> SELECT "users".* FROM "users"
WHERE "users"."active" = 't'
AND ("users"."created_at"
BETWEEN '2013-01-01 05:00:00.000000'
AND '2014-01-01
04:59:59.999999')
In Rails 4.0.0 default_scope is applied lazily at the
very end of the relation.
rails 4.0.0
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class User < ActiveRecord::Base
default_scope { where(active: true) }
scope :signed_in_2013, -> {
except(:where)
.where(created_at: Time.now.all_year) }
end
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class User < ActiveRecord::Base
default_scope { where(active: true) }
scope :signed_in_2013, -> {
except(:where)
.where(created_at: Time.now.all_year) }
end
irb(main):> User.signed_in_2013
=> SELECT "users".* FROM "users"
AND ("users"."created_at"
BETWEEN '2013-01-01 05:00:00.000000'
AND '2014-01-01
04:59:59.999999')
rails edge
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class User < ActiveRecord::Base
default_scope { where(active: true) }
scope :signed_in_2013, -> {
unscoped.where(created_at:
Time.now.all_year) }
end
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class User < ActiveRecord::Base
default_scope { where(active: true) }
scope :signed_in_2013, -> {
unscoped.where(created_at:
Time.now.all_year) }
end
class User < ActiveRecord::Base
default_scope { where(active: true) }
scope :signed_in_2013, -> {
build_default_scope.except(:where).
where(created_at: Time.now.all_year) }
end
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class User < ActiveRecord::Base
has_many :posts
end
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class User < ActiveRecord::Base
has_many :posts
end
irb(main):> User.preload(:posts).to_a
User Load (0.7ms) SELECT "users".* FROM "users"
SELECT "posts".* FROM "posts"
WHERE "posts"."user_id" IN (1)
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class User < ActiveRecord::Base
has_many :posts
end
irb(main):> User.preload(:posts).to_a
User Load (0.7ms) SELECT "users".* FROM "users"
SELECT "posts".* FROM "posts"
WHERE "posts"."user_id" IN (1)
- preload loads the association data in separate queries
- this is how include works in default case
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irb(main):> User.preload(:posts)
.where("posts.desc='ruby is awesome'")
=> PG::Error: ERROR: missing FROM-clause entry for
table "posts"
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irb(main):> User.preload(:posts)
.where("posts.desc='ruby is awesome'")
=> PG::Error: ERROR: missing FROM-clause entry for
table "posts"
irb(main):> User.preload(:posts)
.where("users.name='John'")
=> SELECT "users".* FROM "users"
WHERE (users.name='John')
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irb(main):> User.eager_load(:posts)
SELECT "users"."id" AS t0_r0, "users"."name"
AS t0_r1, "users"."email"
AS t0_r2, "users"."active"
AS t0_r3, "users"."created_at"
AS t0_r4, "users"."updated_at"
AS t0_r5, "posts"."id"
AS t1_r0, "posts"."name"
AS t1_r1, "posts"."title"
AS t1_r2, "posts"."user_id"
AS t1_r3
FROM "users" LEFT OUTER JOIN "posts"
ON "posts"."user_id" = "users"."id"
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irb(main):> User.includes :posts
SELECT "users".* FROM "users"
SELECT "posts".* FROM "posts"
WHERE "posts"."user_id" IN (1)
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irb(main):> User.includes(:posts).references(:posts)
SELECT "users"."id" AS t0_r0, "users"."name"
AS t0_r1, "users"."email"
AS t0_r2, "users"."active"
AS t0_r3, "users"."created_at"
AS t0_r4, "users"."updated_at"
AS t0_r5, "posts"."id"
AS t1_r0, "posts"."name"
AS t1_r1, "posts"."title"
AS t1_r2, "posts"."user_id"
AS t1_r3 FROM "users"
LEFT OUTER JOIN "posts"
ON "posts"."user_id" = "users"."id"
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irb(main):> User.includes(:posts)
.where('posts.name' => "ruby is awesome")
SELECT "users"."id" AS t0_r0, "users"."name"
AS t0_r1, "users"."email"
AS t0_r2, "users"."active"
AS t0_r3, "users"."created_at"
AS t0_r4, "users"."updated_at"
AS t0_r5, "posts"."id"
AS t1_r0, "posts"."name"
AS t1_r1, "posts"."title"
AS t1_r2, "posts"."user_id"
AS t1_r3 FROM "users"
LEFT OUTER JOIN "posts"
ON "posts"."user_id" = "users"."id"
WHERE "posts"."name" = 'ruby is awesome'
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irb(main):> User.joins(:posts)
SELECT "users".* FROM "users"
INNER JOIN "posts"
ON "posts"."user_id" = "users"."id"
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class User < ActiveRecord::Base
has_many :posts
end
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class User < ActiveRecord::Base
has_many :posts
end
irb(main):> user = User.create!
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class User < ActiveRecord::Base
has_many :posts
end
irb(main):> user = User.create!
irb(main):> user.posts.create! name: 'ruby'
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class User < ActiveRecord::Base
has_many :posts
end
irb(main):> user = User.create!
irb(main):> user.posts.create! name: 'ruby'
irb(main):> user.posts[0].name = 'rails'
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class User < ActiveRecord::Base
has_many :posts
end
irb(main):> user = User.create!
irb(main):> user.posts.create! name: 'ruby'
irb(main):> user.posts[0].name = 'rails'
irb(main):> user.save
DEBUG -- : (0.4ms) BEGIN
DEBUG -- : (0.3ms) COMMIT
=> true
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
irb(main):> user = User.create!
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
irb(main):> user = User.create!
irb(main):> user.posts.create! name: 'ruby'
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
irb(main):> user.posts[0].name = 'rails'
irb(main):> user = User.create!
irb(main):> user.posts.create! name: 'ruby'
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
irb(main):> user.posts[0].name = 'rails'
irb(main):> user.save
UPDATE "posts"
SET "name" = $1
WHERE "posts"."id" = 5 [["name", "rails"]]
irb(main):> user = User.create!
irb(main):> user.posts.create! name: 'ruby'
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class Post < ActiveRecord::Base
belongs_to :user, autosave: true
end
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irb(main):> post.user.name = 'John'
class Post < ActiveRecord::Base
belongs_to :user, autosave: true
end
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irb(main):> post.user.name = 'John'
class Post < ActiveRecord::Base
belongs_to :user, autosave: true
end
irb(main):> post.save
UPDATE "users" SET "name" = $1, "updated_at" = $2
WHERE "users"."id" = 4
[["name", "John"],
["updated_at", Thu, 10 Oct 2013 03:35:01 UTC +00:00]]
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class Post < ActiveRecord::Base
belongs_to :user, autosave: true
before_save :add_salutation
def add_salutation
self.user.name = 'Hello ' + self.user.name
end
end
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class Post < ActiveRecord::Base
belongs_to :user, autosave: true
before_save :add_salutation
def add_salutation
self.user.name = 'Hello ' + self.user.name
end
end
class Post < ActiveRecord::Base
# before_belongs_to definition
before_save :add_salutation
belongs_to :user, autosave: true
def add_salutation
self.user.name = 'Hello ' + self.user.name
end
end
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class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
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class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
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class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
irb(main):> post = user.posts.create name: 'rails'
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class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
irb(main):> post = user.posts.create name: 'rails'
irb(main):> post.name = nil
=> nil
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class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
irb(main):> post = user.posts.create name: 'rails'
irb(main):> post.name = nil
=> nil
irb(main):028:0> post.valid?
=> false
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class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
irb(main):> post = user.posts.create name: 'rails'
irb(main):> post.name = nil
=> nil
irb(main):028:0> post.valid?
=> false
irb(main):029:0> user.valid?
=> true
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
irb(main):> post = user.posts.create name: 'rails'
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
irb(main):> post = user.posts.create name: 'rails'
irb(main):> post.name = nil
=> nil
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
irb(main):> post = user.posts.create name: 'rails'
irb(main):> post.name = nil
=> nil
irb(main):028:0> post.valid?
=> false
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class User < ActiveRecord::Base
has_many :posts, autosave: true
end
class Post < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
end
irb(main):> post = user.posts.create name: 'rails'
irb(main):> post.name = nil
=> nil
irb(main):028:0> post.valid?
=> false
irb(main):029:0> user.valid?
=> false
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class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
end
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class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
end
irb(main):> user.object_id
=> 70196526096800
irb(main):> user.posts.first.user.object_id
SELECT "posts".* FROM "posts" WHERE ..........
SELECT "users".* FROM "users" WHERE ..........
=> 70196526747120
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class User < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :user
end
irb(main):> user.object_id
=> 70196526096800
irb(main):> user.posts.first.user.object_id
SELECT "posts".* FROM "posts" WHERE ..........
SELECT "users".* FROM "users" WHERE ..........
=> 70196526747120
rails 4.0.0
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irb(main):> user.object_id
=> 70196526096800
irb(main):> user.posts.first.user.object_id
SELECT "posts".* FROM "posts" WHERE ..........
SELECT "users".* FROM "users" WHERE ..........
=> 70196526747120
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irb(main):> user.object_id
=> 70196526096800
irb(main):> user.posts.first.user.object_id
SELECT "posts".* FROM "posts" WHERE ..........
SELECT "users".* FROM "users" WHERE ..........
=> 70196526747120
rails 4.0.0
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irb(main):> user.object_id
=> 70196526096800
irb(main):> user.posts.first.user.object_id
SELECT "posts".* FROM "posts" WHERE ..........
SELECT "users".* FROM "users" WHERE ..........
=> 70196526747120
rails 4.0.0
irb(main):> user.object_id
=> 70196526096800
irb(main):> user.posts.first.user.object_id
SELECT "posts".* FROM "posts" WHERE ..........
=> 70196526096800
rails edge
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inverse_of
is auto derived in rails
4.1
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inverse_of
is auto derived in rails
4.1
rails edge
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If you do not set the :inverse_of
record, the association will do its
best to match itself up with the
correct inverse.
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If you do not set the :inverse_of
record, the association will do its
best to match itself up with the
correct inverse.
rails edge
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However, associations
that contain the following options
will not have their inverses set
automatically
:conditions
:through
:polymorphic
:foreign_key
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However, associations
that contain the following options
will not have their inverses set
automatically
:conditions
:through
:polymorphic
:foreign_key
rails edge
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class User < ActiveRecord::Base
end
User.new.save
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module ActiveRecord
class Base
......................
include Persistence
.......................
include Validations
........................
include AttributeMethods
........................
include Transactions
........................
end
end
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# module Persistence
def save(*)
create_or_update
rescue ActiveRecord::RecordInvalid
false
end
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# module Persistence
def save(*)
create_or_update
rescue ActiveRecord::RecordInvalid
false
end
def create_or_update
raise ReadOnlyRecord if readonly?
result = new_record? ? create_record : update_record
result != false
end
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# module Validations
def save(options={})
perform_validations(options) ? super : false
end
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# module AttributeMethods
def save(*)
if status = super
@previously_changed = changes
@changed_attributes.clear
end
status
end
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# module Transactions
def save(*) #:nodoc:
rollback_active_record_state! do
with_transaction_returning_status { super }
end
end
def rollback_active_record_state!
remember_transaction_record_state
yield
rescue Exception
restore_transaction_record_state
raise
ensure
clear_transaction_record_state
end
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module ActiveRecord
class Base
......................
include Persistence
.......................
include Validations
........................
include AttributeMethods
........................
include Transactions
........................
end
end
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module ActiveRecord
class Base
......................
include Persistence
.......................
include Validations
........................
include AttributeMethods
........................
include Transactions
........................
end
end
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module ActiveRecord
class Base
......................
include Persistence
.......................
include Validations
........................
include AttributeMethods
........................
include Transactions
........................
end
end
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module ActiveRecord
class Base
......................
include Persistence
.......................
include Validations
........................
include AttributeMethods
........................
include Transactions
........................
end
end
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module ActiveRecord
class Base
......................
include Persistence
.......................
include Validations
........................
include AttributeMethods
........................
include Transactions
........................
end
end
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module ActiveRecord
class Base
......................
include Persistence
.......................
include Validations
........................
include AttributeMethods
........................
include Transactions
........................
end
end
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module ActiveRecord
class Base
......................
include Persistence
.......................
include Validations
........................
include AttributeMethods
........................
include Transactions
........................
end
end
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module ActiveRecord
class Base
......................
include Persistence
.......................
include Validations
........................
include AttributeMethods
........................
include Transactions
........................
end
end
Saturday, October 12, 13
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entering save in transactions
entering save in attribute_methods
entering save in validations
entering save in persistence
leaving save in persistence
leaving save in validations
leaving save in attribute_methods
leaving save in transactions
Life cycle of save
in Active Record
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class Comment < ActiveRecord::Base
belongs_to :post
end
class Author < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :author
has_many :comments
end
Comment.joins(:post)
.merge(Post.joins(:author)
.merge(Author.where(:name => "Joe"))).all
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class Comment < ActiveRecord::Base
belongs_to :post
end
class Author < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :author
has_many :comments
end
Comment.joins(:post)
.merge(Post.joins(:author)
.merge(Author.where(:name => "Joe"))).all
Association named 'author' was not found on Comment
Saturday, October 12, 13
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class Comment < ActiveRecord::Base
belongs_to :post
end
class Author < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :author
has_many :comments
end
Comment.joins(:post)
.merge(Post.joins(:author)
.merge(Author.where(:name => "Joe"))).all
Association named 'author' was not found on Comment
rails 3.2.x
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irb(main):> Post.joins(:author).merge(
Author.where(:name => "J")).joins_values
=> [:author]
irb(main):> Post.joins(:author).merge(
Author.where(:name => "J")).where_values
=> [#, name="name">, @right="Joe">]
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j = Comment.joins(:post).merge(
Post.joins(:author).merge(
Author.where(:name => "Joe"))).joins_values
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irb(main):> j.first
=> :post
irb(main):> j.second
=> []
irb(main):> j.third.class.name
"ActiveRecord::Associations::JoinDependency::JoinAsso
ciation"
irb(main):> j.third.reflection.class.name
=> "ActiveRecord::Reflection::AssociationReflection"
irb(main):> j.third.tables
=> [#]
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irb(main):> j.first
=> :post rails 4.0.0
irb(main):> j.second
=> []
irb(main):> j.third.class.name
"ActiveRecord::Associations::JoinDependency::JoinAsso
ciation"
irb(main):> j.third.reflection.class.name
=> "ActiveRecord::Reflection::AssociationReflection"
irb(main):> j.third.tables
=> [#]
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class Comment < ActiveRecord::Base
belongs_to :post
end
class Author < ActiveRecord::Base
has_many :posts
end
class Post < ActiveRecord::Base
belongs_to :author
has_many :comments
end
Comment.joins(:post)
.merge(Post.joins(:author)
.merge(Author.where(:name => "Joe"))).all
Saturday, October 12, 13
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Neeraj Singh
@neerajdotname
@BigBinary
Saturday, October 12, 13