没有主键的 ActiveRecord 模型 [英] ActiveRecord model without primary key

问题描述

我有一个没有主键的 ActiveRecord 模型 GPA:

I have a ActiveRecord model GPA that doesn't have a primary key:

class GPA < ActiveRecord::Base

end

当我尝试调用 GPA.first.to_json 时，我得到 TypeError: false is not a symbol.我猜这是由于 ActiveRecord 试图查找主键.在没有主键的情况下实现模型的正确方法是什么?

When I try to call GPA.first.to_json I get TypeError: false is not a symbol. I'm guessing that this is due to ActiveRecord trying to lookup the primary key. What is the correct way to implement a model without a primary key?

推荐答案

通常有一些列或列组合在一起形成主键.当您说您的表没有主键时，您的意思是它没有 id 字段吗?

Normally there is either some column or combination of columns which together do form a primary key. When you say your table doesn't have a primary key do you mean it doesn't have an id field?

是否还有另一列是唯一/自然键?如果是这样，您可以这样做:

Is there another column that is a unique/natural key? If so you can do:

class GPA < ActiveRecord::Base
  set_primary_key :strm    # eg column strm is a unique/natural key
end

您还可以将复合键与 复合键 gem 一起使用，如下所示:

You can also use composite keys with the composite keys gem, as follows:

class GPA < ActiveRecord::Base
  set_primary_keys :student_id, :strm
end

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