Question

我有Street模型和Map模型。他们彼此无关。我想使用Map模型帮助选择Leaflet地图的地图（可能是错误的方式，但我试图为地图设置不透明度滑块，现有的叠加层假设点或线）。

所以我想在maps（streets和show）的页面上显示来自edit的表格（所有可用地图的列表）。

streets_controller.rb：

class StreetsController < ApplicationController
  before_action :set_street, only: [:show, :edit, :update, :destroy]

  # Trying to make list of maps available to streets views for working with the map
  @maps = Map.all

  # GET /streets
  # GET /streets.json
  def index
    @streets = Street.all # Without pagination. Added Listing 10.46
    # @streets = Street.paginate(page: params[:page]) # With pagination
  end

  # GET /streets/1
  # GET /streets/1.json
  def show
    gon.streetExtentArray = @street.extent_array
  end

  # GET /streets/new
  def new
    @street = Street.new
    gon.streetExtentArray = @street.extent_array
  end

  # GET /streets/1/edit
  def edit
    gon.streetExtentArray = @street.extent_array
  end

  # POST /streets
  # POST /streets.json
  def create
    @street = Street.new(street_params)

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

  # PATCH/PUT /streets/1
  # PATCH/PUT /streets/1.json
  def update
    respond_to do |format|
      if @street.update(street_params)
        format.html { redirect_to @street, notice: 'Street was successfully updated.' }
        format.json { render :show, status: :ok, location: @street }
      else
        format.html { render :edit }
        format.json { render json: @street.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /streets/1
  # DELETE /streets/1.json
  def destroy
    @street.destroy
    respond_to do |format|
      format.html { redirect_to streets_url, notice: 'Street was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_street
      @street = Street.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def street_params
      params.require(:street).permit(:prevName, :currentName, :dateEarliest, :dateLatest, :where, :extent_json, :extent, :extent_array, :numBlocks, :ref1, :ref2, :ref3, :notes)
    end
end

在streets/show.html.erb

<div class="col-1">
  <% @maps.each do |map| %>
    <p><%= map.name %></p>
  <% end %>      
</div>

其中name是Map模型中的字段。

localhost:3000/maps截图

错误：

未定义的方法`每个＆＃39;为零：NilClass。

这是基本的Rails，但显然超出了我的有限知识。谢谢你的建议。

Answer 1

问题是您没有在控制器中的任何操作中设置@maps = Map.all，因此它在您的视图中不可用，因此@maps为nil。

要解决此问题，请将该行移至show操作：

def show
  @maps = Map.all
  gon.streetExtentArray = @street.extent_array
end

在Rails中显示来自不相关表（模型）的数据

1 个答案: