NoMethodError in LinksController#new in Devise

Question

在我的应用程序中，当我尝试将current_user Devise helper添加到Controller中的new操作时，我会得到以下错误：

undefined method `val' for #<Arel::Nodes::BindParam:0x007fe650498200> 

并在我的代码中突出显示这一行：

@link = current_user.links.build

控制器：

class LinksController < ApplicationController
  before_action :set_link, only: [:show, :edit, :update, :destroy]
  # GET /links
  # GET /links.json
  def index
    @links = Link.all
  end
  # GET /links/1
  # GET /links/1.json
  def show
  end
  # GET /links/new
  def new
    @link = current_user.links.build
  end
  # GET /links/1/edit
  def edit
  end
  # POST /links
  # POST /links.json
  def create
    @link = current_user.links.build(link_params)
    respond_to do |format|
      if @link.save
        format.html { redirect_to @link, notice: 'Link was successfully created.' }
        format.json { render :show, status: :created, location: @link }
      else
        format.html { render :new }
        format.json { render json: @link.errors, status: :unprocessable_entity }
      end
    end
  end
  # PATCH/PUT /links/1
  # PATCH/PUT /links/1.json
  def update
    respond_to do |format|
      if @link.update(link_params)
        format.html { redirect_to @link, notice: 'Link was successfully updated.' }
        format.json { render :show, status: :ok, location: @link }
      else
        format.html { render :edit }
        format.json { render json: @link.errors, status: :unprocessable_entity }
      end
    end
  end
  # DELETE /links/1
  # DELETE /links/1.json
  def destroy
    @link.destroy
    respond_to do |format|
      format.html { redirect_to links_url, notice: 'Link was successfully destroyed.' }
      format.json { head :no_content }
    end
  end
  private
    # Use callbacks to share common setup or constraints between actions.
    def set_link
      @link = Link.find(params[:id])
    end
    # Never trust parameters from the scary internet, only allow the white list through.
    def link_params
      params.require(:link).permit(:title, :url)
    end
end

Answer 1

您似乎忘记将foreign_key user_id添加到links表中。

创建一个迁移添加它链接这个：

$ rails g migration add_user_id_to_links

然后在您的迁移：

class AddUserIdToLinks < ActiveRecord::Migration
  def change
    add_column :links, :user_id, :integer, null: false
    add_index :links, :user_id
  end
end

错误消息不是很清楚或详细，但正如您在本次提交中看到的那样，这在最新的Rails版本中已经得到了纠正。