Recently I was working on a Rails app where every user who signed up also needed to be assigned to an account. Since User and Account are two different models, this can be a bit ugly to handle when Devise expects a single resource. However, by leveraging Reform we can use the Form Object Pattern (#3) to create a RegistrationForm that composes Account and User for registration but doesn’t require creating unnecessary linkages between the actual models.
In this post, I’ll walk through the code on how I made it work. I won’t delve too deeply on actually getting Devise setup since the Devise documentation does a pretty good job of covering that. Just note that you will need to copy the Devise views into your app and you will need a local RegistrationsController that inherits from Devise::RegistrationsController.
The Tests
Let’s start first with the tests. This will show you what we want the final experience to look like.
Controller
This is a basic controller test that lets us validate that we can send a post request with the form parameters and the expected objects get created. Please note, even though we will be using a RegistrationForm object, Devise thinks that we will be using a User object and so we need to use :user params to keep Devise happy.
Please note, I am using factory_girl_rails to get the attributes_for methods. Also note the necessity to specify the devise.mapping; this is discussed further down in Some Final Caveats.
Feature
This is a basic feature test to verify that the process works as expected for a regular site user. The page after a successful login contains the word “Welcome”.
The Form Object
As stated above, we are using Reform to implement a Form Object so that we don’t need to insert any logic into the User or Account models to support capturing fields for both models on user signup.
First take a look at the code for the entire form, then we’ll walk through it step-by-step.
Standard Reform Stuff
The first half of the code is standard Reform stuff. We are using Compositions for cleaner fields, setting up our properties, and configuring validation.
Satisfying Devise Processes
The #active_for_authentication? and #authenticatable_salt methods are to make Devise happy because it’s trying to treat the RegistrationForm as if it was the User model with all of the Devise authenticatable methods mixed in.
Saving the Record
The save method is the most interesting thing here (combined with #build_resource from the RegistrationsController below). The Devise::RegistrationsController#create method expects to work with a standard ActiveModel object where the model is validated at the same time that it is saved. However, Reform uses the validation process to actually populate data into the object and validate it. Saving (or syncing) is a separate step. Here is a snippet of the Devise #create method to see what Devise is doing
As you can see, Devise expects the output from resource.save to indicate if the record is valid. Since we need to check validity differently with Reform, we have our own #save method in the form which fails fast if the RegistrationForm is not valid, but actually handles the save if it is.
The Controller
This is a fairly straightforward implantation of a custom Devise controller with one twist.
As noted above, Reform uses the validation process to populate the form with data from the params hash. Since the #build_resource method is the only time we can get access to the params hash from Devise, we need to validate there so that we have the params data for later usage. But, #build_resource gets called from both #create and #new; and when it’s called from #new the hash is empty. If we try to validate with an empty hash we’ll show the signup form form with validation errors – definitely not something that is conducive to people signing up.
The View
The view is pretty standard. Only significant thing to note is that we are treating the :company_name field as if it belongs to the resource – which in this case it does. It’s not a field on User, but it is a field on RegistrationForm which is the resource for Devise.
Some Final Caveats
Reform and SimpleForm
The latest version of Reform has some issues with SimpleForm. I’ve been working with the Reform maintainer on a patch but you may need to use my fork of Reform.
RSpec and Devise
In order to get RSpec to work correctly with Devise in controller tests, you will need to edit your spec file and your rails_helper.rb (or spec_helper.rb if you’re running an older RSpec). The Devise How To: Test controllers with Rails 3 and 4 (and RSpec) wiki page has the details.