How to: use carrierwave with devise

These instructions assume:

• you've followed the instructions on CarrierWave installation, and generating an AvatarUploader class
• already have a Devise model named User
• you wish to add an avatar to that model using CarrierWave, mounted on a column named avatar

1) Migrate to add the new avatar column to the User model

class AddUserAvatar < ActiveRecord::Migration
  def self.up
    add_column :users, :avatar, :string
  end

  def self.down
    remove_column :users, :avatar
  end
end

2) Add the CarrierWave avatar to your User model

• Add a mount_uploader line at the top of the User class
• Add :avatar, :avatar_cache, and :remove_avatar to the list of accessible attributes you already have generated by Devise.
• Optional: Add avatar validations

This looks something like:

class User < ActiveRecord::Base
  mount_uploader :avatar, AvatarUploader

  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  # Setup accessible (or protected) attributes for your model
  attr_accessible :email, :password, :remember_me, :avatar, :avatar_cache, :remove_avatar

  validates_presence_of   :avatar
  validates_integrity_of  :avatar
  validates_processing_of :avatar
end

3) Add avatar upload to the sign up form (optional)

Assuming you have generated custom Devise views in the standard location, and that you are using Haml, this file is something like app/views/devise/registrations/new.html.haml. You need to:

• Add :multipart => true to the :html hash passed to form_for.
• Add a file_field named :avatar to upload an avatar
• Add a hidden_field named :avatar_cache if you want to preserve uploads across form re-renders due to model validation failures

In Haml, this looks something like this:

= form_for(resource, :as => resource_name, :url => registration_path(resource_name), :html => {:multipart => true}) do |f| 
  - # ...other form fields 
  = f.label :avatar do
    = f.file_field :avatar 
    = f.hidden_field :avatar_cache

4) Add avatar display and upload to the edit form (optional)

Assuming you have generated custom Devise views in the standard location, and that you are using Haml, this file is something like app/views/devise/registrations/edit.html.haml. You need to:

• Add :multipart => true to the :html hash passed to form_for.
• Add an image_tag if you want to display the current avatar
• Add a file_field named :avatar to upload a new avatar
• Add a hidden_field named :avatar_cache if you want to preserve uploads across form re-renders due to model validation failures
• Add a check_box named :remove_avatar if you want to support removing existing avatars.

In Haml, this looks something like this:

= form_for(resource, :as => resource_name, :url => registration_path(resource_name), :html => {:method => :put, :multipart => true}) do |f| 
  - # ...other form fields... 
  - if current_user.avatar.url.present?
    = image_tag(current_user.avatar.url) 
    = f.label :remove_avatar do
      = f.check_box :remove_avatar 
  = f.file_field :avatar  
  = f.hidden_field :avatar_cache