图片不能用回形针保存，导轨4.2

Question

I'm trying to allow a user to upload a picture.

I've read through many of the same questions here and watched several tutorials...I'm still missing something. I see image file parameters are picked up in the console, but are not saved.

Another question, why does rails want the method to be a patch instead of a post?

Thanks for your help.

Here is my model Picture:

class Picture < ActiveRecord::Base

    has_attached_file :picture, styles: { medium: "300x300", thumb: "100x100#" }

    validates_attachment_content_type :picture, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"]

    belongs_to :user
end

Here is my controller:

def upload_image
    User.find(session[:user_id]).pictures.create(pic_params)
    redirect_to :back
end

private
def pic_params
    params.require(:upload).permit(:picture)
end

And here is my view page:

    <%= form_for(@user, :html => {:multipart => true}, :url => { :action => 'upload_image', :user_ud => @user.id }) do |f| %>
        <%= f.file_field "upload[picture]" %>
        <%= f.submit :Upload %>
    <% end %>

From the console:

Started PATCH "/MeetSomeone/upload_image?user_ud=11" for ::1 at 2015-12-24 01:22:38 -0800 Processing by UsersController#upload_image as HTML Parameters: {"utf8"=>"✓", "authenticity_token"=>"/Fhkg2t1vivVlIisE5J5ndRO63PpOELhEwKCLfEELEWvb1XNUvV8HD5VFTnMswCGp+7v8W/wqiuQtOd4GGw2oA==", "user"=>{"upload"=>{"picture"=>#, @original_filename="scott.jpeg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\\"user[upload[picture]]\\"; filename=\\"scott.jpeg\\"\\r\\nContent-Type: image/jpeg\\r\\n">}}, "commit"=>"Upload", "user_ud"=>"11"} User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 11]] Completed 400 Bad Request in 3ms (ActiveRecord: 0.2ms)

ActionController::ParameterMissing (param is missing or the value is empty: upload): app/controllers/users_controller.rb:52:in pic_params' app/controllers/users_controller.rb:46:in upload_image'

Answer 1

Do this:

def pic_params
   params.require(:user).permit(upload: [:picture])
end

The problem you have currently is that you're params hash is expecting...

"upload" => {
   "picture => "..."
}

Because you're using form_for @user , it's building the params hash as...

"user" => {
  "upload" => {
     "picture" => {
       ....
     }
  }
}

This is why you're getting the error:

param is missing or the value is empty: upload

Your structure is really bad (I've corrected some of it below); you'd do well to read up on the params class to see how it works.

---

I would personally do the following:

#config/routes.rb
resources :pictures #-> url.com/pictures/new

#app/controllers/pictures_controller.rb
class PicturesController < ApplicationController
   before_action :user

   def new
     @picture = @user.pictures.new
   end

   def create
     @picture = @user.pictures.new pic_params
     @picture.save
   end

   private

   def pic_params
      params.require(:picture).permit(:image)
   end

   def user
      @user = User.find params[:session_id]
   end
end

#app/views/pictures/new.html.erb
<%= form_for @picture, multipart: true do |f| %>
   <%= f.file_field :picture %>
   <%= f.submit %>
<% end %>

This will be accessible at url.com/pictures/new

I know it's not adherent to the structure of your application; I'll explain how you'd get it working with your app in a second.

The important thing to note about Rails is its object orientated nature; every time you create a record, it's actually an object . The problem you have is that you're getting confused with which object you're trying to create, leading your params hash to be incorrect.

By using a pictures controller (rather than adding to the users controller), you are able to create a Picture object on the back of the user association. The way you're doing it currently would require you to use accepts_nested_attributes_for , which can get tricky:

---

The way you should be doing what you're doing is to use accepts_nested_attributes_for - which basically means that you're able to send nested data to an associated model.

Since you wish to use your users controller, it would be better for you to send the picture object as nested --

#config/routes.rb
resources :users do
   match :upload_image, via: [:get, :patch], on: :collection #-> url.com/users/upload_image #-> you're using session[:user_id] so no need for member route
end

#app/models/user.rb
class User < ActiveRecord::Base
   has_one :picture
   accepts_nested_attributes_for :picture
end

#app/controllers/users_controller.rb
class UsersController < ApplicationController
   before_action :set_user

   def upload_image
      if request.get?
         @user.build_picture unless @user.picture
      elsif request.patch?
         @user.update pic_params
         redirect_to @user
      end
   end

   private

   def pic_params
      params.require(:user).permit(picture_attributes: [:picture])
   end

   def set_user
      @user = User.find params[:user_id] #-> this is 
   end
end 

This will allow you to use:

#app/views/users/upload_image.html.erb
<%= form_for @user do |f| %>
   <%= f.fields_for :picture do |p| %>
      <%= p.file_field :picture %>
   <% end %>
   <%= f.submit %>
<% end %>

---

Finally, a pro-tip I give out is the paperclip_defaults option for Paperclip:

#config/application.rb
...
config.paperclip_defaults = {
   styles: { medium: "300x300", thumb: "100x100#" }
}

This will set the default options for any Paperclip enabled model you have (which can be overridden of course).

Ultimately, it means that you're able to clean up your models quite simply:

#app/models/picture.rb
class Picture < ActiveRecord::Base
    belongs_to :user

    has_attached_file :picture
    validates :picture, content_type: { content_type: ["image/jpg", "image/jpeg", "image/png", "image/gif"] }
end