Question

我在rails中做自我关联。我有Request模型，它应该引用自己。这就是我所拥有的：

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class Request < ActiveRecord::Base

  has_many :sub_requests, class_name: 'Request',
                          foreign_key: 'parent_request_id'

  belongs_to :parent_request, class_name: 'Request'

end

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和我的迁移：

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class CreateRequests < ActiveRecord::Migration
  def change
    create_table :requests do |t|
      t.references :parent_request, index: true
  
    end
  end
end

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但是我收到如下错误：

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PG::UndefinedColumn: ERROR:  column requests.parent_request_id does not exist

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Answer 1

你运行rake db：migrate吗？如果你这样做，那就试试这个：

class Request < ActiveRecord::Base
  has_many :sub_requests, class_name: 'Request', foreign_key: 'parent_request_id', primary_key: 'id'
  belongs_to :parent_request, class_name: 'Request', foreign_key: 'parent_request_id', primary_key: 'id'
end

class CreateRequests < ActiveRecord::Migration
  def change
    create_table :requests do |t|
      t.integer :parent_request_id, index: true
    end
  end
end

Rails中的自我关联添加了外键错误

1 个答案: