Question

我已经关注了Michael Hartl的教程，现在我想将照片添加到微博中。但是当我提交微博时，图像没有保存在数据库中，而在dvlpmt日志中我可以读取未允许的参数：图像 我查看了其他帖子并做了他们的建议，但它对我不起作用。

模型

micropost.rb

class Micropost < ActiveRecord::Base
  belongs_to :user
  has_one :photo
  default_scope -> { order('created_at DESC') }
  validates :content, presence: true, length: { maximum: 140 }
  validates :user_id, presence: true
end

photo.rb

class Photo < ActiveRecord::Base
    belongs_to :micropost
    has_attached_file :image
end

控制器

photos_controller.rb

class PhotosController < ApplicationController
  before_action :signed_in_user, only: [:create, :destroy, :index]

  def create
    @photo = Photo.new(photo_params)

    respond_to do |format|
      if @photo.save
        format.html { redirect_to @photo, notice: 'Photo was successfully created.' }
        format.json { render action: 'static_pages/home', status: :created, location: @photo }
      else
        format.html { render action: 'static_pages/home' }
        format.json { render json: @photo.errors, status: :unprocessable_entity }
      end
    end
  end

  private
    def photo_params
      params.require(:photo).permit(:image)
    end
end

microposts_controller.rb

class MicropostsController < ApplicationController
  before_action :signed_in_user, only: [:create, :destroy]

  def create
    @micropost = current_user.microposts.build(micropost_params)
    if @micropost.save
      flash[:success] = "Micropost created!"
      redirect_to root_url
    else
      @feed_items = []
      render 'static_pages/home'
    end
  end

  private

  def micropost_params
    params.require(:micropost).permit(:content, photo_attributes: [:photo_id, :image])
  end
end

视图

_micropost_form.html.erb 我不知道如何构建这种形式，我尝试了很多不同的配方

<%= form_for(@micropost) do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">
    <%= f.text_area :content, placeholder: "Compose new micropost..." %>
  </div>

  <%= f.fields_for :image, :html => { :multipart => true } do |builder| %>
    <%= f.file_field :image, :f => builder %>
  <% end %>

  <%= f.submit "Post", class: "btn btn-large btn-primary" %>
<% end %>

当我想提交表单时，没关系，但是对于表微博，列“photo_id”为空。照片未保存在数据库中。

服务器日志

Started POST "/microposts" for 127.0.0.1 at 2013-11-27 15:06:06 +0100
Processing by MicropostsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"u7MWO+E9jM8/g+6RwquQ7XLA3PR+ohQFAx0tmwNOfuY=", "micropost"=>{"content"=>"Hello world", "image"=>#<ActionDispatch::Http::UploadedFile:0x00000003401a48 @tempfile=#<Tempfile:/tmp/RackMultipart20131127-4010-1r6qt80>, @original_filename="paint.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"micropost[image]\"; filename=\"paint.jpg\"\r\nContent-Type: image/jpeg\r\n">}, "commit"=>"Post"}
  [1m[36mUser Load (0.2ms)[0m  [1mSELECT "users".* FROM "users" WHERE "users"."remember_token" = '342df8f039f7f40698b3691f77d2539dc8b9c101' LIMIT 1[0m
Unpermitted parameters: image
  [1m[35m (0.1ms)[0m  begin transaction
  [1m[36mSQL (0.4ms)[0m  [1mINSERT INTO "microposts" ("content", "created_at", "updated_at", "user_id") VALUES (?, ?, ?, ?)[0m  [["content", "Hello world"], ["created_at", Wed, 27 Nov 2013 14:06:06 UTC +00:00], ["updated_at", Wed, 27 Nov 2013 14:06:06 UTC +00:00], ["user_id", 101]]
  [1m[35m (145.1ms)[0m  commit transaction
Redirected to http://localhost:3000/
Completed 302 Found in 153ms (ActiveRecord: 145.7ms)

我现在完全陷入困境，如果你能找到可以帮助我找到解决方案的东西，谢谢你！

Answer 1

您需要在Micropost课程中使用accepts_nested_attributes_for。

class Micropost < ActiveRecord::Base
  belongs_to :user
  has_one :photo
  accepts_nested_attributes_for :photo
  default_scope -> { order('created_at DESC') }
  validates :content, presence: true, length: { maximum: 140 }
  validates :user_id, presence: true
end

看起来你的表格还是将图像与你的微博相关联，而不是微博的照片。看一下fields_for的Ruby文档。您可以尝试将表单的一部分更改为此吗？

<%= f.fields_for :photo, :html => { :multipart => true } do |photo_fields| %>
  <%= photo_fields.file_field :image %>
<% end %>

如果这样做，您需要确保在呈现视图的控制器操作中调用@micropost.build_photo。

我认为您不需要在photo_id的强参数中列出microposts_controller.rb。一旦记录保存到数据库，就应该设置它。

您还可以阅读building complex forms上的Rails指南。该指南讨论了如何设置模型，视图和控制器来处理嵌套属性。如果你还没有，他们对strong parameters的描述可能会有所帮助。

未经许可的参数，嵌套表单 - Ruby On Rails

1 个答案: