CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3imagemagickpapercliperb
Brendon Baughn
Brendon Baughn

Reputation: 150

undefined method `image' in my view

I am using Paperclip, and my only problem is that in my image tag, I have an undefined method "image".

<%= image_tag @posts.image.url(:medium) %>

is where my error is occurring. When I loaded a new migration, I accidentally did "rails g paperclip user image" instead of "rails g paperclip posts image" so I went into my code and changed "user" to "posts." I asked something similar and someone mentioned that it was with my schema.rb file(?).

Just to be safe, this is my post controller:

 class PostsController < ApplicationController
    def index
        @posts = Post.all.order('created_at DESC')
    end

    def new
        @post = Post.new

        if @post.save
            redirect_to @post
        else
            render 'new'
        end
    end

    def create
        @post = Post.new(post_params)
        @post.save

        redirect_to @post
    end

    def show
        @post = Post.find(params[:id])
    end

    def edit
        @post = Post.find(params[:id])
    end

    def update
        @post = Post.find(params[:id])

        if @post.update(params[:post].permit(:title, :body))
            redirect_to @post
        else
            render 'edit'
        end
    end

    def destroy
        @post = Post.find(params[:id])
        @post.destroy

        redirect_to root_path
    end


    private
    def post_params
        params.require(:post).permit(:title, :body, :image)
    end
end

but here is my migration file:

class AddAttachmentImageToUsers < ActiveRecord::Migration
  def self.up
    change_table :posts do |t|
      t.attachment :image
    end
  end

  def self.down
    remove_attachment :posts, :image
  end
end

and my user.rb file:

has_attached_file :image, :styles => { large: '600x600>', medium: '300x300>', thumb: '150x150#' }
  validates_attachment_content_type :image, content_type: /\Aimage\/.*\Z/

Upvotes: 2

Views: 3020

Answers (3)

Hunter Wang
Hunter Wang

Reputation: 1

I think the problem might be how you changing "user" to "posts.".it would be okay to just change controller or view name,but change model is a different thing that you have to generate a migration to change table name

Upvotes: 0

Richard Peck
Richard Peck

Reputation: 76784

From the comments and your code, it looks like your @posts variable is either empty or undefined. To add to the original answer, here's what I'd do:

#app/controllers/posts_controller.rb
class PostsController < ActionController::Base
   def index
      @posts = Post.all.order(created_at: :desc)
   end
end

#app/views/posts/index.html.erb
<% if @posts.any? %>
   <% @posts.each do |post| %>
       <%= image_tag post.image.url(:medium) %>
   <% end %>
<% end %>

You must have the @posts variable referenced in the view which corresponds to the action you're running. From seeing your comments, it appears this might not be the case.

You need to be referencing single instances of the Post model, in order to have the image method available.

If it is not available, it either means you don't have the @posts variable declared properly, or your Paperclip gem is not set up properly.

this is my user.rb file

haha okay. THIS is the problem.

Make sure you put this in your post.rb file:

#app/models/post.rb
class Post < ActiveRecord::Base
    has_attached_file :image, :styles => { large: '600x600>', medium: '300x300>', thumb: '150x150#' }
    validates_attachment_content_type :image, content_type: /\Aimage\/.*\Z/
end

Paperclip basically links stored images to database records. Thus, in order to append the image method to your model, you have to have the Paperclip options appended to it.

Putting the paperclip calls in user.rb will add the image method to your User model. You need to put those lines in the Post model.

BTW I met the guys who made Paperclip:

enter image description here

that it was with my schema.rb file(?).

The schema.rb file is located in /config/db/schema.rb.

Essentially, each time you migrate to your DB, the schema is updated, so that in the event you need to repopulate the db, Rails will be able to pull a pre-built set of SQL calls to do it.

Indeed, it is recommended that you use rake db:schema:load to rebuild a database (rather than rake db:migrate). HOWEVER (VERY IMPORTANT), IT DELETES ANY DATA in that database, making it unadvisable to use it for anything other than building new db's.

You can read about Schema.rb here.

In regards to what your friend was saying, if you go into your schema.rb file, you'll be able to see which table has the paperclip columns added to it. By generating the migration for the users table, you may have caused a conflict.

Upvotes: 2

Athar
Athar

Reputation: 3268

You need to access image for one post at a time so you need to traverse the posts collection and fetch image for each post like this

<% @posts.each do |post| %>
  <%= image_tag post.image.url(:medium) %>
<% end %>

Upvotes: 2

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