我怎样才能有条件地调用ActiveRecord中的属性？

Question

我有一段代码如下：

foreign_object = (some_test) ? nil : <some foreign_object>

Document.where(foreign_id: foreign_object, status: "Working", ... )

如果foreign_object为nil，则只能找到foreign_id = NULL的Documents。有没有办法有条件地将foreign_id放入？我基本上想写：

Document.where(foreign_id: foreign_object if foreign_object, status: "Working", ...)

Answer 1

我在这种情况下这样做：

 documents = Document.where(status: 'working')
 documents = documents.where(foreign_id: foreign_object) if foreign_object