Rails 对象在创建时丢失参数值

Posted 2023-02-25

【中文标题】Rails 对象在创建时丢失参数值

【英文标题】：Rails object loses params value while creating it

【发布时间】：2016-12-14 19:22:59

【问题描述】：

我有带有一些参数（价格、类别 ID、图像等）的 产品 模型。

以部分形式创建新产品时，通过select_tag 选择类别，并通过图像上传器 Carrierwave 上传图像。当我让用户在crop.html.erb 文件中裁剪上传的图像时，会发生不好的事情。用户裁剪图像，点击提交，使用路径作为更新（不太确定哪个 HTTP 协议），并被重定向到产品编辑页面，因为产品不知何故丢失了 category_id 参数。表单显示选择类别错误（input_fields 中的所有其他参数不会丢失）。

我的尝试就像定义 crop 方法并在那里设置类别，但没有运气......

products_controller.rb：

  def edit
    @categories = Category.all
  end

  def create
    @product = Product.new(product_params)
    @product.category_id = params[:category_id]
    @product.user_id = current_user.id

    respond_to do |format|
      if @product.save
        if params[:product][:image].present?
          format.html  render :crop 
        else
          format.html  redirect_to @product, notice: 'Product was successfully created.' 
          format.json  render :show, status: :created, location: @product 
        end
      else
        format.html  render :new 
        format.json  render json: @product.errors, status: :unprocessable_entity 
      end
    end
  end

  def update
    @product.category_id = params[:category_id]

    respond_to do |format|
      if @product.update(product_params)
        if params[:product][:image].present?
          format.html  render :crop 
        else
          format.html  redirect_to @product, notice: 'Product was successfully updated.' 
          format.json  render :show, status: :ok, location: @product 

          @products = Product.all
          ActionCable.server.broadcast 'products',
            html: render_to_string('store/index', layout: false)
        end
      else
        format.html  render :edit 
        format.json  render json: @product.errors, status: :unprocessable_entity 
      end
    end
  end

crop.html.erb（在产品文件夹中）：

<%= image_tag @product.image_url(:large), id: "cropbox" %>

<h4>Preview</h4>
<div style="width:300px; height:200px; overflow:hidden;">
  <%= image_tag @product.image.url(:large), :id => "preview" %>
</div>

<%= form_for @product do |f| %>
  <% %w[x y w h].each do |attribute| %>
    <%= f.hidden_field "crop_#attribute" %>
  <% end %>
  <div class="actions">
    <%= f.submit "Crop" %>
  </div>
<% end %>

我没有尝试设置存储 category_id 的回调，但我想知道这是个好主意吗？有什么帮助吗？谢谢！

编辑 - 还添加了一个部分表单，但它工作正常 - 只是为了你的好奇心：

<%= form_for(product, hmtl:  multipart: true  ) do |f| %>
...
  <div class="field">
    <%= f.label :category %>
    <%= select_tag(:category_id, options_from_collection_for_select(Category.all, :id, :name, @product.category_id), include_blank: "Select Category") %>
  </div>

更新

这些操作的日志：

Started GET "/products/new" for ::1 at 2016-12-15 09:03:31 +0200
Processing by ProductsController#new as HTML
  [1m[36mCart Load (0.4ms)[0m  [1m[34mSELECT  "carts".* FROM "carts" WHERE "carts"."id" = $1 LIMIT $2[0m  [["id", 5], ["LIMIT", 1]]
  [1m[36mCACHE (0.0ms)[0m  [1m[34mSELECT  "carts".* FROM "carts" WHERE "carts"."id" = $1 LIMIT $2[0m  [["id", 5], ["LIMIT", 1]]
  [1m[36mUser Load (2.0ms)[0m  [1m[34mSELECT  "users".* FROM "users" WHERE "users"."id" = $1 ORDER BY "users"."id" ASC LIMIT $2[0m  [["id", 1], ["LIMIT", 1]]
  Rendering products/new.html.erb within layouts/application
  [1m[36mCategory Load (0.4ms)[0m  [1m[34mSELECT "categories".* FROM "categories"[0m
  Rendered products/_form.html.erb (6.2ms)
  Rendered products/new.html.erb within layouts/application (11.2ms)
  [1m[36mCACHE (0.0ms)[0m  [1m[34mSELECT "categories".* FROM "categories"[0m
  [1m[36mLineItem Load (0.5ms)[0m  [1m[34mSELECT "line_items".* FROM "line_items" WHERE "line_items"."cart_id" = $1[0m  [["cart_id", 5]]
Completed 200 OK in 127ms (Views: 113.2ms | ActiveRecord: 3.3ms)


Started POST "/products" for ::1 at 2016-12-15 09:03:40 +0200
Processing by ProductsController#create as HTML
  Parameters: "utf8"=>"✓", "authenticity_token"=>"eWZuqL6AqcN8wknjEL115ax9uBnpY4b9eP0o2xN2aPntd61YKyc4Ym1lUgjV1YrXfZbPr57HANXy7Kz5swCtlg==", "product"=>"title"=>"kj", "description"=>"kj", "image"=>#<ActionDispatch::Http::UploadedFile:0x007fe40ba4abe0 @tempfile=#<Tempfile:/var/folders/dn/zq9x2jkd4856kwhfj5gbz2tc0000gn/T/RackMultipart20161215-3987-1adfacs.png>, @original_filename="Screen Shot 2016-12-05 at 09.14.48.png", @content_type="image/png", @headers="Content-Disposition: form-data; name=\"product[image]\"; filename=\"Screen Shot 2016-12-05 at 09.14.48.png\"\r\nContent-Type: image/png\r\n">, "price"=>"98", "quantity"=>"98", "category_id"=>"1", "commit"=>"Create Product"
  [1m[36mCart Load (0.3ms)[0m  [1m[34mSELECT  "carts".* FROM "carts" WHERE "carts"."id" = $1 LIMIT $2[0m  [["id", 5], ["LIMIT", 1]]
  [1m[36mCACHE (0.0ms)[0m  [1m[34mSELECT  "carts".* FROM "carts" WHERE "carts"."id" = $1 LIMIT $2[0m  [["id", 5], ["LIMIT", 1]]
  [1m[36mUser Load (0.7ms)[0m  [1m[34mSELECT  "users".* FROM "users" WHERE "users"."id" = $1 ORDER BY "users"."id" ASC LIMIT $2[0m  [["id", 1], ["LIMIT", 1]]
  [1m[35m (0.3ms)[0m  [1m[35mBEGIN[0m
  [1m[36mCategory Load (0.3ms)[0m  [1m[34mSELECT  "categories".* FROM "categories" WHERE "categories"."id" = $1 LIMIT $2[0m  [["id", 1], ["LIMIT", 1]]
  [1m[35mSQL (1.0ms)[0m  [1m[32mINSERT INTO "products" ("title", "description", "price", "quantity", "created_at", "updated_at", "category_id", "user_id", "image") VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9) RETURNING "id"[0m  [["title", "kj"], ["description", "kj"], ["price", #<BigDecimal:7fe40ccf9110,'0.98E2',9(18)>], ["quantity", 98], ["created_at", 2016-12-15 07:03:41 UTC], ["updated_at", 2016-12-15 07:03:41 UTC], ["category_id", "1"], ["user_id", 1], ["image", "Screen_Shot_2016-12-05_at_09.14.48.png"]]
  [1m[35m (3.1ms)[0m  [1m[35mCOMMIT[0m
  Rendering products/crop.html.erb within layouts/application
  Rendered products/crop.html.erb within layouts/application (3.1ms)
  [1m[36mCategory Load (0.7ms)[0m  [1m[34mSELECT "categories".* FROM "categories"[0m
  [1m[36mLineItem Load (0.3ms)[0m  [1m[34mSELECT "line_items".* FROM "line_items" WHERE "line_items"."cart_id" = $1[0m  [["cart_id", 5]]
Completed 200 OK in 957ms (Views: 127.8ms | ActiveRecord: 6.7ms)

所以我注意到它在没有特定 ID 的情况下呈现 products/crop.html.erb，所以我在路由中添加了：

  resources :products do
    get 'crop', on: :member
  end

和 products_controller 创建动作：

...
    respond_to do |format|
      if @product.save
        if params[:product][:image].present?
          format.html  render crop_product_path(@product) 
        else
...

仍然是同样的错误，必须选择一个类别。 需要注意的是 - 如果只是去编辑产品（但不是来自 crop 操作），类别就按预期的那样放在那里......

【问题讨论】：

尝试在您的crop.html 视图中为category_id 添加hidden_field。并将其设置为@product.category_id。然后您可以稍后检索update 操作中的值

嗯，不错的收获，但后来我得到了undefined method :category_id=>"1"'...试图在产品控制器的裁剪操作中定义产品...隐藏字段：<%= f.hidden_field :category_id => @product.category_id %>

如果您将隐藏字段放在表单中，它将位于product 下，因此要在更新操作中获取category_id，它将位于params[:product][:category_id] 下

看看apidock.com/rails/ActionView/Helpers/FormHelper/hidden_field中如何设置隐藏字段

行得通！非常感谢。你可以发布作为答案吗？所以我可以接受它

【参考方案1】：

由于表单只提交其中定义的收集参数，您应该添加一个隐藏字段以在crop.html视图中设置category_id

<%= image_tag @product.image_url(:large), id: "cropbox" %>

<h4>Preview</h4>
<div style="width:300px; height:200px; overflow:hidden;">
  <%= image_tag @product.image.url(:large), :id => "preview" %>
</div>

<%= form_for @product do |f| %>
  <% %w[x y w h].each do |attribute| %>
    <%= f.hidden_field "crop_#attribute" %>
  <% end %>
  <%= f.hidden_field :category_id %>
  <div class="actions">
    <%= f.submit "Crop" %>
  </div>
<% end %>

现在，当您提交表单时，您将在服务器上的params[:product][:category_id] 收到category_id