标签:unscope default posts rails scope Post where
1.使用default_scope
class Post < ActiveRecord::Base default_scope { where(published: true) } end2.1.1 :001 > Post.all
Post Load (0.2ms) SELECT "posts".* FROM "posts" WHERE "posts"."published" = 1
2.使用default_scope需要小心的问题
一、
2.1.1 :004 > Post.new => #<Post id: nil, title: nil, published: true, created_at: nil, updated_at: nil>
二、
class Post < ActiveRecord::Base default_scope { where(published: true) } belongs_to :user end class User < ActiveRecord::Base has_many :posts end 2.1.1 :001 > User.first.posts Post Load (0.3ms) SELECT "posts".* FROM "posts" WHERE "posts"."published" = 't' AND "posts"."user_id" = ? [["user_id", 1]]
三、使用假删除的时候,要注意unscoped的使用,unscope 会取消所有的scope, 包括deleted_at
3. 取消default scope unscoped的使用
class User < ActiveRecord::Base default_scope { where tester: false } scope :testers, -> { unscope(:where).where tester: true } scope :with_testers, -> { unscope(:where).where tester: [true, false] } # ... end
eg:Foo.unscope(where: :bar)
orscope :not_default, -> { unscope(where: :bar) }
Foo.not_default
It is currently possible to unscope
stuff like: :where,:select, :group, :order, :lock, :limit, :offset, :joins, :includes, :from, :readonly, :having
.
But still please avoid using of default_scope
if you can. It's for your own good.
参考链接:
https://stackoverflow.com/questions/1834159/overriding-a-rails-default-scope
https://www.thinbug.com/q/25087336
标签:unscope,default,posts,rails,scope,Post,where 来源: https://www.cnblogs.com/hello-ruby/p/16266353.html
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