Default_url in Paperclip Broke with Asset Pipeline Upgrade

问题

I'm using Paperclip and have a default_url option like this for one of my attachments:

:default_url => '/images/missing_:style.png'

The asset pipeline obviously doesn't like this since the directories moved. What's the best way to handle this? I have two styles for this picture (:mini and :thumb).

回答1:

:default_url => ActionController::Base.helpers.asset_path('missing_:style.png')

Then put the default images in app/assets/images/

回答2:

Tested only on Rails 4.

To make it work in production, we have to pass the name of an existing file to the asset_path helper. Passing a string containing a placeholder like "missing_:style.png" therefore doesn't work. I used a custom interpolation as a workaround:

# config/initializers/paperclip.rb
Paperclip.interpolates(:placeholder) do |attachment, style|
  ActionController::Base.helpers.asset_path("missing_#{style}.png")
end

Note that you must not prefix the path with images/ even if your image is located in app/assets/images. Then use it like:

# app/models/some_model.rb
has_attached_file(:thumbnail,
                  :default_url => ':placeholder',
                  :styles => { ... })

Now default urls with correct digest hashes are played out in production.

The default_url option also takes a lambda, but I could not find a way to determine the requested style since interpolations are only applied to the result of the lambda.

回答3:

Just make sure that in your views all your paperclip images are rendered with image_tag.

<%= image_tag my_model.attachment.url(:icon) %>

That way, all of paperclip's :crazy :symbol :interpolation will have happened to the url string before Rails tries to resolve it to an asset in the pipeline.

Also, make sure your :default_url is asset compatible...if missing_icon.png is at app/assets/images/missing_icon.png, then :default_url should be simply "missing_:style.png"

<%= image_tag my_model.attachment.url(:icon) %>
# resolves to...
<%= image_tag "missing_icon.png" %>
# which in development resolves to...
<img src="/assets/missing_icon.png">

回答4:

I got the error(even for a single style) at assets:precompile with

:default_url => ActionController::Base.helpers.asset_path('missing.png')

So I hooked with a method like this

# supposing this is for avatar in User model

has_attached_file :avatar,
   :styles => {..},    
   :default_url => lambda { |avatar| avatar.instance.set_default_url}

def set_default_url
  ActionController::Base.helpers.asset_path('missing.png')
end

I didn't try for multiple styles, but this works for my situation.

回答5:

this works for me:

has_attached_file :avatar, :styles => { :small => "52x52",
:medium => "200x200>", :large=> "300x300", :thumb => "100x100>" },
                              :default_url => "missing_:style.png"

just place images in your assets/images folder named: missing_large.png, missing_medium.png, missing_small.png and missing_thumb.png

回答6:

In rails 4.0.0 and paperclip 4.1.1 this worked for me:

has_attached_file :avatar,
  styles: { medium: '300x300#', small: '100x100#', thumb: '25x25#' },
  default_url: ->(attachment) { 'avatar/:style.gif' },
  convert_options: { all: '-set colorspace sRGB -strip' }

回答7:

I ended up having to use something like the following.

DEFAULT_URL = "#{Rails.configuration.action_controller.asset_host}#{Rails.configuration.assets.prefix}/:attachment/:style/missing.png"
has_attached_file :art, :styles => { :large => "398x398#", :medium => "200x200#", :small=>"100x100#", :smaller=>"50x50#", :smallest=>"25x25"}, :path=>"images/:attachment/:id/:style/:basename.:extension", :default_url => DEFAULT_URL

I statically compile the assets and was getting an error in production, this helped me.

回答8:

In your model file, change this line:

has_attached_file :avatar, styles: { medium: "300x300>", thumb: "100x100>" }, default_url: "/images/:style/missing.png"

by removing this:

/images/

Create a folder for each style, in this example medium and thumb, in assests/images and place an image called missing.png there (or whatever name you want it to have of course, as long as it matches the file name in the model)

Worked for me.

回答9:

I've solved this problem by using a custom interpolator.

The problem from other solutions that suggest using

:default_url => ActionController::Base.helpers.asset_path('missing_:style.png')

is that you will get an error saying "missing_style.png" is not precompiled.

I created an initializer with the following code:

module Paperclip
  module AssetPipeline
    module Interpolator
      def self.interpolate(pattern, *args)
        ActionController::Base.helpers.asset_path Paperclip::Interpolations.interpolate(pattern, *args)
      end
    end
  end
end

Then in my model I would do:

has_attached_file :image, interpolator: Paperclip::AssetPipeline::Interpolator, ...

回答10:

Just remove the / from /images/pic.png: images/pic.png

来源：https://stackoverflow.com/questions/9646549/default-url-in-paperclip-broke-with-asset-pipeline-upgrade