The CarrierWave and Cloudinary gems provide us with an easy way to allow image uploads through forms.
In your Gemfile, include
gem "carrierwave"
gem "cloudinary"
and then run bundle install in the Terminal.
In the file config/environment.rb, add this line to the end:
require "carrierwave/orm/activerecord"
You need to have a column of type String in whichever table that you want to
attach a file upload to. This column will, ultimately, store the URL of the
uploaded file after CarrierWave hosts it.
If you already included the column when you generated your resource, great. Skip to the next step.
If not, you have to add it. For example, here we add a column called avatar to
the users table, which we plan to store an image in:
rails generate migration add_avatar_to_users avatar:string
rails db:migrate
In your case, it may be song, transcript, image, etc.
From the command line:
rails generate uploader Avatar
In your case, change Avatar to match whatever you are trying to upload / the
column you added to the table: Song, Transcript, Image, etc.
Restart your bin/server.
In the relevant model add mount_uploader :avatar, AvatarUploader.
# app/models/user.rb
class User < ApplicationRecord
mount_uploader :avatar, AvatarUploader
end
Again, customize to match your use case. :avatar should be the column you
created, and AvatarUploader should be whatever uploader you generated.
We need an <input type="file"> in our form to handle the upload. If you
already have a type="text" input, change it; or if you don’t, add a new one:
<input type="file" id="avatar" name="avatar" class="form-control">
We also need to change the <form> tag itself to allow files to be uploaded by
adding the enctype="multipart/form-data" attribute:
<form action="/create_user" method="post" class="form-horizontal" enctype="multipart/form-data">
In your create/update actions, assign the new file upload just like any other form parameter:
@user.avatar = params.fetch(:avatar)
That should be it!
CarrierWave will, by default, process the upload and then store it in your
public folder, so that you can use it just like any other URL on the internet.
For example, we could now do
<img src="<%= user.avatar %>" class="img-responsive">
CarrierWave works fine locally at this point, but it’s going to break if you try to host your project live on Heroku. That’s because Heroku won’t let you permanently write to the public folder of a live application.
If you’re going to deploy your app to Heroku, then you’ll need to find a file hosting service, like Amazon AWS S3, to store any uploaded files. Fortunately, there’s a great service called Cloudinary that makes it easy to host uploaded images; and they have a generous free tier.
To integrate Cloudinary, first adjust your ImageUploader file so it looks like:
class ImageUploader < CarrierWave::Uploader::Base
include Cloudinary::CarrierWave
end
Most importantly, make sure you remove the line that says:
storage :file
Create an initializer file called carrierwave.rb in config/initializers and add the following content:
CarrierWave.configure do |config|
config.cache_storage = :file
end
Next, you’ll need to sign up for a Cloudinary account. and get your API info. You can find your cloud name by going to Settings and clicking the Account tab. You can find your API key and secret by going to Settings and clicking the Security tab.
For security, it’s best to store your keys in environment variables. Read more on the how and why this is important in the guide on storing your credientials securely.
After pushing to Heroku, you’ll need to manually add these environment variables (Heroku calls them “Config Vars”) in the Settings tab of your application.
Finally, create an initializer file called cloudinary.rb in config/initializers and add the following content:
Cloudinary.config do |config|
config.cloud_name = ENV["CLOUDINARY_CLOUD_NAME"]
config.api_key = ENV["CLOUDINARY_API_KEY"]
config.api_secret = ENV["CLOUDINARY_API_SECRET"]
config.cdn_subdomain = true
end