error with multiple image upload

问题

Iam new to rails 4 i want add multiple images.i have a product model and picture model in my app.product has many picture and picture has a image and its a paperclip attachment but i cant access images in my view models/products.rb

class Product < ActiveRecord::Base
belongs_to :user
belongs_to :category
has_many :comments , dependent: :destroy
has_many :pictures, :dependent => :destroy
end

models/picture.rb

class Picture < ActiveRecord::Base
belongs_to :product
accepts_nested_attributes_for :images,:allow_destroy => true
has_attached_file :image,:styles => {
:thumb    => ['100x100#',  :jpg, :quality => 70],
:preview  => ['480x480#',  :jpg, :quality => 70],
:large    => ['600>',      :jpg, :quality => 70],
:retina   => ['1200>',     :jpg, :quality => 30]
},
:path => ":rails_root/public/images/:id/:filename",
:url  => "/images/:id/:filename"

do_not_validate_attachment_file_type :image
end

View page

<div class="row">
                <% @products.each do |product| %>
                <div class="col-sm-3  col-lg-3 col-md-3">
                    <div class="thumbnail">

                        <%= product.image.url(:thumb) %>
                        <div class="caption">
                            <h4 class="pull-right">Rs.<%= product.price %>   </h4>
                            <h4><%= link_to 'Show', product %>
                            </h4>
                            <p><strong>Name:</strong>&emsp;  <%= product.name %></span></p>
                            <% if !product.description.blank? %>
                                <p><strong>Description:</strong> <%= product.description %></p>
                            <% end %>
                            <% if !product.reason.blank? %>
                                <p><strong>Reason:</strong><%= product.reason %></p>
                            <% end %>

                        </div>

                    </div>
                </div>
                <% end %>
</div>

回答1:

You're trying to call a nested method on your parent model.

You have:

#app/models/product.rb
class Product < ActiveRecord::Base
   has_many :pictures
end

#app/models/picture.rb
class Picture < ActiveRecord::Base
   belongs_to :product
   has_attached_file :image
end

This means that you will have to call:

<% @products.each do |product| %>
   <% product.pictures.each do |picture| %>
      <%= picture.image.url %>
   <% end %>
<% end %>

You're receiving a noMethod error because you're trying to call image on your Product object (which doesn't exist):

<%= picture.image.url #-> doesn't exist %>

Fix

The fix is a little more involved than you realize.

Specifically, you have to ensure that you're able to add/create the nested Picture objects, which comes from the accepts_nested_attributes_for method:

#app/models/product.rb
class Product < ActiveRecord::Base
   has_many :pictures
   accepts_nested_attributes_for :pictures 
end

This will allow you to create the appropriate form & controller actions:

#app/controllers/products_controller.rb
class ProductsController < ApplicationController
   def new
      @product = Product.new
      @product.pictures.build
   end

   def create
      @product = Product.new product_params
      @product.save
   end

   private

   def product_params
      params.require(:product).permit(..., pictures_attributes: [:image])
   end
end

You'll then use fields_for:

#app/views/products/new.html.erb
<%= form_for @product do |f| %>
   <%= f.fields_for :pictures do |p| %>
     <%= p.file_field :image %>
   <% end %>
   <%= f.submit %>
<% end %>

This will allow you to save new Picture's / images with a new product, then using the code above, you'll be able to show them!!

Bonus

A pro tip I keep sharing is paperclip_defaults:

#config/application.rb
...
config.paperclip_defaults = {
   :styles => {
       :thumb    => ['100x100#',  :jpg, :quality => 70],
       :preview  => ['480x480#',  :jpg, :quality => 70],
       :large    => ['600>',      :jpg, :quality => 70],
       :retina   => ['1200>',     :jpg, :quality => 30] #-> is this correct formatting?
   },
   :path => ":rails_root/public/images/:id/:filename",
   :url  => "/images/:id/:filename"
}

Instead of including all the styles in your Picture model, you can set them as "defaults" in your config/application.rb - which will allow you to just call has_attached_file :image, changing the styles as you require:

#app/models/picture.rb
class Picture < ActiveRecord::Base
   has_attached_file :image #-> will use the defaults which can be overridden as required
end

回答2:

Please try this:

<% for asset in @picture.assets %>
 <%= link_to image_tag(asset.image.url(:thumb)), asset.image.url(:original) %>
<% end %>

I hope it will help you. You can also follow below link:

https://github.com/Emerson/Multiple-File-Uploads-with-Paperclip-and-Rails-3/blob/master/app/views/posts/show.html.erb

来源：https://stackoverflow.com/questions/34460209/error-with-multiple-image-upload

标签

ruby-on-rails

paperclip