Ruby 在 Rails 上：ActiveRecord::AssociationTypeMismatch

Question

我在尝试提交记录时遇到 ActiveRecord::AssociationTypeMismatch 错误。

Subject(#88982676) expected, got String(#20223000)

查看：

<%= f.collection_select :subject, Subject.order(:subject), :subject, :subject, {prompt: "Select a subject"}, {class: "form-control"} %>

控制器：

 def create
            @homework = current_user.homeworks.build(homework_params)
            if @homework.save
                redirect_to homeworks_path
            else
                render 'new'
            end
        end
...

def homework_params
            params.require(:homework).permit(:subject, :description, :date, :completed_at)
        end

型号：Homework.rb

class Homework < ActiveRecord::Base

 validates :subject, presence:true

    belongs_to :subject

def completed?
    !completed_at.blank?
end


end

Subject.rb

class Subject < ActiveRecord::Base

     has_many :homeworks

     def to_s
     subject
  end
end

以前可以用，但突然不行了。我确实将 table 的名称更改为 "subject" 并相应地更改了视图和控制器。现在好像在找id？主题是一个字符串。有什么建议吗？谢谢。

Answer 1

根据你的关联模型，你的作业属性应该是这样的：

subject_id:integer description:string date:datetime completed_at:datetime

因此，您应该在 homework_params

中允许 subject_id，而不是 subject

至于collection_select方法，应该是这样的：

f.collection_select :subject_id, Subject.order(:subject), :id, :subject

Ruby 在 Rails 上：ActiveRecord::AssociationTypeMismatch

Ruby on Rails: ActiveRecord::AssociationTypeMismatch

activerecord

ruby-on-rails

ruby-on-rails-3