作用域查询中的ActiveRecord OR子句

statuses = %w(sick healthy hungry) query = User.scoped(:joins => 'left outer join pets on pets.user_id = users.id', :conditions => { 'pets.id' => nil, 'users.job_status' => stati }) 

鉴于上面的代码，是否可以在:conditions添加一个OR子句来表示类似的东西

 where (pets.id is NULL AND users.status IN ('sick', 'healthy', 'hungry')) OR (users.gender = 'male') 

Answer 1

您可以使用MetaWhere gem执行以下操作

 statuses = %w(sick healthy hungry) query = User.include(:pets).where( ('pets.id' => nil, 'users.job_status' => statuses) | ('users.gender' => 'male') ) 

| 符号用于OR条件。

PS ： include指令使用LEFT OUTER JOIN因此不需要手动编写JOIN代码。

Answer 2

您可以使用SQL条件而不是哈希条件：

 query = User.scoped( :joins => 'left outer join pets on pets.user_id = users.id', :conditions => [ '(pets.id is null AND users.status IN (?)) OR (users.gender = ?)', statuses, 'male' ] ) 

要么：

 query = User.scoped( :joins => 'left outer join pets on pets.user_id = users.id', :conditions => [ '(pets.id is null AND users.status IN (:statuses)) OR (users.gender = :gender)', { :status => statuses, :gender => 'male' } ] ) 

缺点是你必须避免尝试pets.is = NULL手动。