Rails form object with reform-rails with collections not working or validating

Question

I am using the reform-rails gem In order to utilize a form object in my rails project.

I realize a form object is probably overkill for the example code I use below, but it is for demonstration purposes.

In the form I am creating a user, and associated to that user record are two user_emails.

# models/user.rb
class User < ApplicationRecord
  has_many :user_emails
end

# models/user_email.rb
class UserEmail < ApplicationRecord
  belongs_to :user
end

Notice that I am not using accepts_nested_attributes_for :user_emails within the User model. It appears to me that one of the main points of form objects is that it helps you get away from using accepts_nested_attributes_for, so that is why I am attempting to do this without it. I got that idea from this video which talks about refactoring fat models. I have the link pointing to the section of the video on form objects, and he expresses how much he dislikes accepts_nested_attributes_for.

I then proceed to create my user_form:

# app/forms/user_form.rb
class UserForm < Reform::Form
  property :name
  validates :name, presence: true

  collection :user_emails do
    property :email_text
    validates :email_text, presence: true
  end
end

So the user_form object wraps a user record and then a couple of user_email records associated to that user record. There are form-level validations on the user and on the user_email records this form wraps:

• the user#name must have a value
• each user_email#email_text must have a value

If the form is valid: then it should create one user record and then a couple of associated user_email records. If the form is not valid: then it should re-render the form with error messages.

I will show what I have in the controller thus far. For brevity: only displaying the new action and the create action:

# app/controllers/users_controller.rb
class UsersController < ApplicationController

  def new
    user = User.new
    user.user_emails.build
    user.user_emails.build
    @user_form = UserForm.new(user)
  end

  def create
    @user_form = UserForm.new(User.new(user_params))
    if @user_form.valid?
      @user_form.save
      redirect_to users_path, notice: 'User was successfully created.'
    else
      render :new
    end
  end

  private
    def user_params
      params.require(:user).permit(:name, user_emails_attributes: [:_destroy, :id, :email_text])
    end
end

Lastly: the form itself:

# app/views/users/_form.html.erb
<h1>New User</h1>
<%= render 'form', user_form: @user_form %>
<%= link_to 'Back', users_path %>

---

# app/views/users/_form.html.erb
<%= form_for(user_form, url: users_path) do |f| %>
  <% if user_form.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(user_form.errors.count, "error") %> prohibited this user from being saved:</h2>

      <ul>
      <% user_form.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :name %>
    <%= f.text_field :name %>
  </div>
  <% f.fields_for :user_emails do |email_form| %>
    <div class="field">
      <%= email_form.label :email_text %>
      <%= email_form.text_field :email_text %>
    </div>
  <% end  %>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

As a test: here is the form with inputted values:

Now I proceed to submit. What should happen is there should be a validation error because a value for that second email must be present. However, when submitted here are the logs:

Parameters: {"utf8"=>"✓", "authenticity_token"=>”123abc==", "user"=>{"name"=>"neil", "user_emails_attributes"=>{"0"=>{"email_text"=>"email_test1"}, "1"=>{"email_text"=>""}}}, "commit"=>"Create User"}

ActiveModel::UnknownAttributeError (unknown attribute 'user_emails_attributes' for User.):

So there is some issue with my form object.

How can I get this form object to work? Is it possible to use reform_rails and get this form object to work without using accepts_nested_attributes? Ultimately: I just want to get the form objet to work.

Some resource I have already explored in addition to the reform-rails docs:

• reform_example project on gitlab, outdated
• article on reform
• another article

My first attempt to make a form object was with the virtus gem, but I could not seem to get that one working either. I did post a stackoverflow question for that implementation as well.

Carder

You might want to check how Reform handles instantiation and validation of collection objects from parameters in the case that they've never been persisted. accepts_nested_attributes_for has options around rejecting blanks, for example. – Killingsworth

Answer 1

Complete Answer:

Models:

# app/models/user.rb
class User < ApplicationRecord
  has_many :user_emails
end

# app/models/user_email.rb
class UserEmail < ApplicationRecord
  belongs_to :user
end

Form Object:

# app/forms/user_form.rb
# if using the latest version of reform (2.2.4): you can now call validates on property 
class UserForm < Reform::Form
  property :name, validates: {presence: true}

  collection :user_emails do
    property :email_text, validates: {presence: true}
  end
end

Controller:

# app/controllers/users_controller.rb
class UsersController < ApplicationController
  before_action :user_form, only: [:new, :create]

  def new 
  end

  # validate method actually comes from reform this will persist your params to the Class objects
  # you added to the UserForm object. 
  # this will also return a boolean true or false based on if your UserForm is valid. 
  # you can pass either params[:user][:user_emails] or params[:user][user_email_attributes]. 
  # Reform is smart enough to pick up on both.
  # I'm not sure you need to use strong parameters but you can. 

  def create    
    if @user_form.validate(user_params)
      @user_form.save
      redirect_to users_path, notice: 'User was successfully created.'
    else
      render :new
    end
  end

  private

  # call this method in a hook so you don't have to repeat
  def user_form
    user = User.new(user_emails: [UserEmail.new, UserEmail.new])
    @user_form ||= UserForm.new(user)
  end 

  # no need to add :id in user_emails_attributes
  def user_params
    params.require(:user).permit(:name, user_emails_attributes: [:_destroy, :email_text])
   end
 end

The Form:

# app/views/users/new.html.erb
<h1>New User</h1>
<%= render 'form', user_form: @user_form %>
<%= link_to 'Back', users_path %>

---

#app/views/users/_form.html.erb
<%= form_for(user_form, url: users_path) do |f| %>
  <% if user_form.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(user_form.errors.count, "error") %> prohibited this user from being saved:</h2>

      <ul>
      <% user_form.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :name %>
    <%= f.text_field :name %>
  </div>
  <%= f.fields_for :user_emails do |email_form| %>
    <div class="field">
      <%= email_form.label :email_text %>
      <%= email_form.text_field :email_text %>
    </div>
  <% end  %>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

Pout

Wow! Thanks so much! Please approve my minor edits which include all the pieces (for completion sake) and I will gladly mark your answer as the accepted answer! – Carder

I will be working through your answer on the virtus implementation question too. If you are feeling up to it: feel free to checkout my raw rails 5 implementation question on form objects. Unfortunately I'm pretty much out of reputation points so I can't offer much of a bounty on that one. – Carder

you have saved my life :D – Wavelength

Answer 2

I finally got it working!!!

First, I couldn't get it saving the collection on Rails 5. I created a 4.2.6 and it works our of the box. I suggest you to create an issue on the github repository page of the Reform gem.

So, this is the working code :

models/user.rb

class User < ActiveRecord::Base
  has_many :user_emails
end

models/user_email.rb

class UserEmail < ActiveRecord::Base
  belongs_to :user
end

user_form.rb

class UserForm < Reform::Form

  property :name
  validates :name, presence: true

  collection :user_emails, populate_if_empty: UserEmail do
    property :email_text
    validates :email_text, presence: true
  end
end

The populate_if_empty is important when validation occurs.

And the controller create method:

def create
  @user_form = UserForm.new(User.new)
  if @user_form.validate(user_params)
    @user_form.save
    redirect_to users_path, notice: 'User was successfully created.'
  else
    render :new
  end
end

This will validates your User model AS WELL AS any nested associations.

There you have it! Dry models, validations and saving of the model and associations.

I hope this helps!

Montmartre