has_one ， belongs_to 和 create_before 在 rails

Question

我用脚手架创建了 2 个模型：

1. 问题
2. 记者

我想为每个问题创建 1 个报告者，并使用 before_create 创建报告者。

我在数据库的问题表中按整数类型生成reporter_id。 下面的代码显示了问题和报告者的行动和模型：

问题.rb

class Problem < ActiveRecord::Base
  has_one :reporter
  before_create :build_reporter
end

reporter.rb

class Reporter < ActiveRecord::Base

  belongs_to :problem

end

problems_controller.rb

class ProblemsController < ApplicationController

  before_action :set_problem, only: [:show, :edit, :update, :destroy]

  def index
    @problems = Problem.all
  end

  def show
  end

  def new
    @problem = Problem.new
  end

  def edit
  end

  def create
    @problem = Problem.new(problem_params)

    respond_to do |format|
      if @problem.save
        format.html { redirect_to @problem, notice: 'Problem was successfully created.' }
        format.json { render action: 'show', status: :created, location: @problem }
      else
        format.html { render action: 'new' }
        format.json { render json: @problem.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    respond_to do |format|
      if @problem.update(problem_params)
        format.html { redirect_to @problem, notice: 'Problem was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @problem.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @problem.destroy
    respond_to do |format|
      format.html { redirect_to problems_url }
      format.json { head :no_content }
    end
  end

私人的 def set_problem @problem = Problem.find(params[:id]) 结束

def problem_params
  params.require(:problem).permit(:reporter_id, :describe_id, :datetime, :trace_code, :status)
end

结束

reporter_controller.rb

class ReportersController < ApplicationController
  before_action :set_reporter, only: [:show, :edit, :update, :destroy]

  def index
    @reporters = Reporter.all
  end

  def show
  end

  def new
    @reporter = Reporter.new
  end

  def edit
  end

  def update
    respond_to do |format|
      if @reporter.update(reporter_params)
        format.html { redirect_to @reporter, notice: 'Reporter was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @reporter.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @reporter.destroy
    respond_to do |format|
      format.html { redirect_to reporters_url }
      format.json { head :no_content }
    end
  end

  private
    def set_reporter
      @reporter = Reporter.find(params[:id])
    end

    def reporter_params
      params.require(:reporter).permit(:user_name, :gomrok_name, :phone_number)
    end
end

当我在 localhost:3000/problems 中选择新问题按钮时，会显示文本字段，但是当完成文本字段并选择创建问题按钮时，我会收到此错误：

ActiveRecord::UnknownAttributeError in ProblemsController#create 


unknown attribute: problem_id
Extracted source (around line #31):   


respond_to do |format|
  if @problem.save
    format.html { redirect_to @problem, notice: 'Problem was successfully created.' }
    format.json { render action: 'show', status: :created, location: @problem }
  else

problem_id 是什么？！

我没用过。

我想在数据库的问题表中设置报告者 ID；如何使用 before_create 或 after_create 创建报告者并将报告者 ID 保存在问题表中？

Answer 1

您错误地设置了关系。你所拥有的是problems 表中的reporter_id 列。在1-1 关系中，foreign_key 是在belongs_to 一侧创建的。因此，您的代码应如下所示：

class Problem < ActiveRecord::Base
  belongs_to :reporter
end

class Reporter < ActiveRecord::Base    
  has_one :problem   
  before_create :build_problem
end