Question

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 })

根据上述准则,可在<代码>上添加一个OR条款:conditions ,以表示类似情况。

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

Answer 1

您可使用MetaWhere gem

statuses = %w(sick healthy hungry)

query = User.include(:pets).where(
  ( pets.id  => nil,  users.job_status  => statuses) |
  ( users.gender  =>  male )
)

<代码>>>>代码/代码>符号为<编码>>。

<>PS>/strong>: <include Directive use LEFT OUTER JOIN,因此无需将JOIN编码。

Answer 2

You could use an SQL condition instead of a Hash condition:

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 
    ]
)

Or:

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  }
    ]
)

倒数是,你必须避免手头尝试<代码>pets.is = NUL。

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