Question

我正在尝试使用和学习载波。我的问题是我能够上传文件，但在尝试编辑时我收到错误uninitialized constant ImageFile

继承我的images_controller.rb

class ImagesController < ApplicationController
  before_action :set_image, only: [:show, :edit, :update, :destroy]

  # GET /images
  # GET /images.json
  def index
    @images = Image.all
  end

  # GET /images/1
  # GET /images/1.json
  def show
  end

  # GET /images/new
  def new
    @image = Image.new
  end

  # GET /images/1/edit
  def edit
  end

  # POST /images
  # POST /images.json
  def create
    @image = Image.new(image_params)

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

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

  # DELETE /images/1
  # DELETE /images/1.json
  def destroy
    @image.destroy
    respond_to do |format|
      format.html { redirect_to images_url, notice: 'Image was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

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

    # Never trust parameters from the scary internet, only allow the white list through.
    def image_params
      params.require(:image).permit(:Title, :ImageFile, :Comments)
    end


end

这是在new和edit

中使用的_form.html.erb

<%= form_for @image, html: { multipart: true } do |f| %>
  <% if @image.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@image.errors.count, "error") %> prohibited this image from being saved:</h2>

      <ul>
      <% @image.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :Title %><br>
    <%= f.text_field :Title %>
  </div>
  <div class="field">
    <%= f.label :ImageFile %><br>
    <%= f.file_field :ImageFile %>
  </div>
  <div class="field">
    <%= f.label :Comments %><br>
    <%= f.text_field :Comments %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

这是image.rb

class Image < ActiveRecord::Base
  # attr_accessible :Comments, :ImageFile, :Title
  mount_uploader :ImageFile, ImageCreatorUploader
end

请帮助

Answer 1

您的Image课程出错了。您没有正确安装上传器。您将类名的符号传递给mount_uploader方法。您需要传递字段名称的符号。替换：

class Image < ActiveRecord::Base
  mount_uploader :ImageFile, ImageCreatorUploader
end

使用：

class Image < ActiveRecord::Base
  mount_uploader :image_file, ImageCreatorUploader
end

方法名称不应大写。只有班级名称。

此外，由于您使用的是strong_parameters，因此您不需要attr_accessible。你已经评论了这条线，但我想我会指出这一点。您还在此处将您的属性名称大写，这是不正确的。使用snake_case。

Answer 2

在ruby中，属性名称，变量名称，方法名称都应以小写字母开头。以大写字母开头的名称被视为常量和类名。

将对班级属性（:Title，:ImageFile，:Comments）的所有引用更改为snake_case（:title，:image_file，{{ 1}}）

尝试更新映像文件时未初始化的常量错误

2 个答案: