James Wilding's Weblog

You want to run Rails 3. You want to use the excellent Paperclip plugin to mess with your attached files. Not a problem.

It Just Works

Paperclip on Rails 3 now just works.

Back in February 2010, I wrote about how to use Paperclip on an early beta release of Rails 3 — back then, a few small hacks were required to get Paperclip running. Now Rails 3 is at beta 4, and it’s safe to assume that we’re as close as we can be to an official Rails release — minus a few last minute tweaks, of course — and both the framework itself and the Paperclip plugin are more stable and more compatible. The good news, then, is that it’s very easy to use the Rails 3 and Paperclip together.

How To Use Paperclip With Rails 3

These instructions are good for Rails 3 beta 4, and Paperclip 9223a917. They’ll probably work on other versions of Rails and Paperclip, too.

1. Install Rails 3
2. Create a new Rails app
3. Install Paperclip
4. Create a model
5. Create a controller and views
6. Define your routes

You can find the important files (controller, model, views, and routes) in this gist, and the full application code is available on Github.

Install Rails 3

Install the latest prerelease of Rails with the following:

$ gem install rails --pre

Create a new Rails app

The command for creating Rails apps has changed in Rails 3. In the bright new future, everything is done using “rails” ¹:

$ rails new paperclip_example

Install Paperclip

Paperclip’s master branch is now good to go with Rails 3. Install from Github thus:

$ rails plugin install git://github.com/thoughtbot/paperclip.git

Create a model

In order to work with Paperclip, your model needs a few special database columns. In this case, I’m creating a User class which will have an attached avatar image.

$ rails generate model User \
avatar_file_name:string \
avatar_content_type:string \
avatar_file_size:integer \
avatar_updated_at:datetime
$ rake db:migrate

I use Paperclip’s has_attached_file method to define my avatar attachment:

class User < ActiveRecord::Base
  has_attached_file :avatar, :styles => {
    :thumb => '50x'
  }
end

Create a controller and views

I’m setting up a simple UsersController with index, new, and create actions (and corresponding routes). You’ll probably want to go further, but if all you’re interested in is proof-of-concept then this is enough.

$ rails generate controller Users

See this gist for the code in my UsersController, and the HTML in my views.

Define your routes

In config/routes.rb:

PaperclipExample::Application.routes.draw do |map|
  resources :users, :only => [:index, :new, :create]
  root :to => 'users#index'
end

Lastly, if you’re mapping your app’s root to a controller, remember to delete public/index.html.

And You’re Done

That’s really all there is to it. Use rails server to start your app and view the results. Did it work for you?

Update: you should read this more recent article for an explanation of how to use Paperclip with the latest beta release of Rails 3.

I got Paperclip working on Rails 3 today. Here’s how.

First, I found (by accident) a branch in the Paperclip repository on Github called “Rails 3″. Call me crazy but I thought that might be worth a try.

Normally you’d install Rails 3 plugins using rails plugin install, but in this case I used git submodule:

These two commands checkout the rails3 branch of Paperclip into vendor/plugins/paperclip, as a Git submodule. If you don’t understand Git submodules, you can read about them here.

I also found that Paperclip wasn’t properly handling image styles; the ‘Paperclip’ section of this post explains how I fixed this (a word of warning: it’s a simple one-line edit which solved my problem but is untested with regard to the rest of Paperclip).

As always, feel free to post questions or feedback in the comments. Good luck!

So it’s Sunday, and rather than go to church I decided to take Rails 3 for a test drive. As you do. How did it go? In the main, very smoothly — a couple of bugs, which you Googlers might find it useful to know about, and some nice new stuff.

Bug: the rails command

Failed completely :) Rails my_app fails with “no value provided for required arguments ‘app_path’”. The solution to this is easy, though: first, get a local copy of Rails 3 (I cloned the Rails repo: git clone git://github.com/rails/rails.git) and then use this command instead:

The rubygems require is necessary for Rails 3 to load all the gems it needs to run.

Thoughts

The Rails command

In Rails 3, the rails command replaces script/console, script/server, etc. This is nice: commands are more meaningful (run the rails server with “rails server”), and easier to type.

ActiveRecord’s new finder syntax

ActiveRecord’s new finder syntax is lovely, and has some nice performance gains which you can read about on other blogs. Named scopes look good:

I’m going to write more about this soon.

Speed

Call me crazy but Rails 3 seems faster. Maybe this has something to do with the fact that it uses Erubis instead of ERB, or maybe I’m just easily impressed :)

Paperclip (tiny bug)

Paperclip has a branch called Rails3: I went out on a limb and guessed that was for Rails 3. It almost just worked, except for one thing: custom attachment styles weren’t being created.

If you’ve used paperclip, you’ll know you can do this:

Well, those :medium, :wide, and :small variations weren’t being created. I didn’t have time to investigate properly but this seemed to have something to do with Paperclip’s callbacks (which were returning false even when they shouldn’t be): my one line hack/fix for this:

I freely admit that this might break other parts of Paperclip, but it works for me.

Conclusions

Overall, Rails 3 feels very nice. As you’d expect from a beta it almost just works, and I’ve made a working app with it in a day. Super easy! Next up: deploying to Heroku.