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Class: ActiveRecord::QueryMethods::WhereChain

Relationships & Source Files
Inherits: Object
Defined in: activerecord/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.

Class Method Summary

Instance Method Summary

Constructor Details

.new(scope) ⇒ WhereChain

This method is for internal use only.
[ GitHub ] 

  


# File 'activerecord/lib/active_record/relation/query_methods.rb', line 15



def initialize(scope) # :nodoc:
  @scope = scope
end


  







Instance Method Details



  

    #associated(*associations)  
  



  

    

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


  



  [ GitHub ]


  

  


# File 'activerecord/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.options[: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)  
  



  

    

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


  



  [ GitHub ]


  

  


# File 'activerecord/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.options[: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)  
  



  

    

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 ActiveRecord::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')
# => []


  



  [ GitHub ]


  

  


# File 'activerecord/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


  








  

    #scope_association_reflection(association)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/relation/query_methods.rb', line 138



def scope_association_reflection(association)
  reflection = @scope.klass._reflect_on_association(association)
  unless reflection
    raise ArgumentError.new("An association named `:#{association}` does not exist on the model `#{@scope.name}`.")
  end
  reflection
end