Class: ActiveRecord::QueryMethods::WhereChain
- Inherits:
-
Object
- Object
- ActiveRecord::QueryMethods::WhereChain
- Defined in:
- lib/active_record/relation/query_methods.rb
Overview
WhereChain
objects act as placeholder for queries in which where
does not have any parameter. In this case, where
can be chained to return a new relation.
Instance Method Summary collapse
-
#associated(*associations) ⇒ Object
Returns a new relation with joins and where clause to identify associated relations.
-
#initialize(scope) ⇒ WhereChain
constructor
:nodoc:.
-
#missing(*associations) ⇒ Object
Returns a new relation with left outer joins and where clause to identify missing relations.
-
#not(opts, *rest) ⇒ Object
Returns a new relation expressing WHERE + NOT condition according to the conditions in the arguments.
Constructor Details
#initialize(scope) ⇒ WhereChain
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 15 def initialize(scope) # :nodoc: @scope = scope end |
Instance Method Details
#associated(*associations) ⇒ Object
Returns a new relation with joins and where clause to identify associated relations.
For example, posts that are associated to a related author:
Post.where.associated(:author)
# SELECT "posts".* FROM "posts"
# INNER JOIN "authors" ON "authors"."id" = "posts"."author_id"
# WHERE "authors"."id" IS NOT NULL
Additionally, multiple relations can be combined. This will return posts associated to both an author and any comments:
Post.where.associated(:author, :comments)
# SELECT "posts".* FROM "posts"
# INNER JOIN "authors" ON "authors"."id" = "posts"."author_id"
# INNER JOIN "comments" ON "comments"."post_id" = "posts"."id"
# WHERE "authors"."id" IS NOT NULL AND "comments"."id" IS NOT NULL
You can define join type in the scope and associated
will not use ‘JOIN` by default.
Post.left_joins(:author).where.associated(:author)
# SELECT "posts".* FROM "posts"
# LEFT OUTER JOIN "authors" "authors"."id" = "posts"."author_id"
# WHERE "authors"."id" IS NOT NULL
Post.left_joins(:comments).where.associated(:author)
# SELECT "posts".* FROM "posts"
# INNER JOIN "authors" ON "authors"."id" = "posts"."author_id"
# LEFT OUTER JOIN "comments" ON "comments"."post_id" = "posts"."id"
# WHERE "author"."id" IS NOT NULL
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# File 'lib/active_record/relation/query_methods.rb', line 88 def associated(*associations) associations.each do |association| reflection = scope_association_reflection(association) unless @scope.joins_values.include?(reflection.name) || @scope.left_outer_joins_values.include?(reflection.name) @scope.joins!(association) end if reflection.[:class_name] self.not(association => { reflection.association_primary_key => nil }) else self.not(reflection.table_name => { reflection.association_primary_key => nil }) end end @scope end |
#missing(*associations) ⇒ Object
Returns a new relation with left outer joins and where clause to identify missing relations.
For example, posts that are missing a related author:
Post.where.missing(:author)
# SELECT "posts".* FROM "posts"
# LEFT OUTER JOIN "authors" ON "authors"."id" = "posts"."author_id"
# WHERE "authors"."id" IS NULL
Additionally, multiple relations can be combined. This will return posts that are missing both an author and any comments:
Post.where.missing(:author, :comments)
# SELECT "posts".* FROM "posts"
# LEFT OUTER JOIN "authors" ON "authors"."id" = "posts"."author_id"
# LEFT OUTER JOIN "comments" ON "comments"."post_id" = "posts"."id"
# WHERE "authors"."id" IS NULL AND "comments"."id" IS NULL
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# File 'lib/active_record/relation/query_methods.rb', line 123 def missing(*associations) associations.each do |association| reflection = scope_association_reflection(association) @scope.left_outer_joins!(association) if reflection.[:class_name] @scope.where!(association => { reflection.association_primary_key => nil }) else @scope.where!(reflection.table_name => { reflection.association_primary_key => nil }) end end @scope end |
#not(opts, *rest) ⇒ Object
Returns a new relation expressing WHERE + NOT condition according to the conditions in the arguments.
#not accepts conditions as a string, array, or hash. See QueryMethods#where for more details on each format.
User.where.not("name = 'Jon'")
# SELECT * FROM users WHERE NOT (name = 'Jon')
User.where.not(["name = ?", "Jon"])
# SELECT * FROM users WHERE NOT (name = 'Jon')
User.where.not(name: "Jon")
# SELECT * FROM users WHERE name != 'Jon'
User.where.not(name: nil)
# SELECT * FROM users WHERE name IS NOT NULL
User.where.not(name: %w(Ko1 Nobu))
# SELECT * FROM users WHERE name NOT IN ('Ko1', 'Nobu')
User.where.not(name: "Jon", role: "admin")
# SELECT * FROM users WHERE NOT (name = 'Jon' AND role = 'admin')
If there is a non-nil condition on a nullable column in the hash condition, the records that have nil values on the nullable column won’t be returned.
User.create!(nullable_country: nil)
User.where.not(nullable_country: "UK")
# SELECT * FROM users WHERE NOT (nullable_country = 'UK')
# => []
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# File 'lib/active_record/relation/query_methods.rb', line 49 def not(opts, *rest) where_clause = @scope.send(:build_where_clause, opts, rest) @scope.where_clause += where_clause.invert @scope end |