Instance Public methods
default_scopes?(all_queries: false) Link
Checks if the model has any default scopes. If all_queries is set to true, the method will check if there are any default_scopes for the model where all_queries
is true.
unscoped(&block) Link
Returns a scope for the model without the previously set scopes.
class Post < ActiveRecord::Base
belongs_to :user
def self.default_scope
where(published: true)
end
end
class User < ActiveRecord::Base
has_many :posts
end
Post.all # Fires "SELECT * FROM posts WHERE published = true"
Post.unscoped.all # Fires "SELECT * FROM posts"
Post.where(published: false).unscoped.all # Fires "SELECT * FROM posts"
User.find(1).posts # Fires "SELECT * FROM posts WHERE published = true AND posts.user_id = 1"
User.find(1).posts.unscoped # Fires "SELECT * FROM posts"
This method also accepts a block. All queries inside the block will not use the previously set scopes.
Post.unscoped {
Post.limit(10) # Fires "SELECT * FROM posts LIMIT 10"
}
Instance Private methods
default_scope(scope = nil, all_queries: nil, &block) Link
Use this macro in your model to set a default scope for all operations on the model.
class Article < ActiveRecord::Base
default_scope { where(published: true) }
end
Article.all
# SELECT * FROM articles WHERE published = true
The default_scope
is also applied while creating/building a record. It is not applied while updating or deleting a record.
Article.new.published # => true
Article.create.published # => true
To apply a default_scope
when updating or deleting a record, add all_queries: true
:
class Article < ActiveRecord::Base
default_scope -> { where(blog_id: 1) }, all_queries: true
end
Applying a default scope to all queries will ensure that records are always queried by the additional conditions. Note that only where clauses apply, as it does not make sense to add order to queries that return a single object by primary key.
Article.find(1).destroy
# DELETE ... FROM `articles` where ID = 1 AND blog_id = 1;
(You can also pass any object which responds to call
to the default_scope
macro, and it will be called when building the default scope.)
If you use multiple default_scope
declarations in your model then they will be merged together:
class Article < ActiveRecord::Base
default_scope { where(published: true) }
default_scope { where(rating: 'G') }
end
Article.all
# SELECT * FROM articles WHERE published = true AND rating = 'G'
This is also the case with inheritance and module includes where the parent or module defines a default_scope
and the child or including class defines a second one.
If you need to do more complex things with a default scope, you can alternatively define it as a class method:
class Article < ActiveRecord::Base
def self.default_scope
# Should return a scope, you can call 'super' here etc.
end
end
# File activerecord/lib/active_record/scoping/default.rb, line 129 def default_scope(scope = nil, all_queries: nil, &block) # :doc: scope = block if block_given? if scope.is_a?(Relation) || !scope.respond_to?(:call) raise ArgumentError, "Support for calling #default_scope without a block is removed. For example instead " \ "of `default_scope where(color: 'red')`, please use " \ "`default_scope { where(color: 'red') }`. (Alternatively you can just redefine " \ "self.default_scope.)" end default_scope = DefaultScope.new(scope, all_queries) self.default_scopes += [default_scope] end