Rails Form Object with Virtus: has_many association

Question

I am having a tough time figuring out how to make a form_object that creates multiple associated objects for a has_many association with the virtus gem.

Answer 1

You have an issue because you haven't whitelisted any attributes under :emails. This is confusing, but this wonderful tip from Pat Shaughnessy should help set you straight.

This is what you're looking for, though:

params.require(:user_form).permit(:name, { emails: [:email_text, :id] })

Note the id attribute: it's important for updating the records. You'll need to be sure you account for that case in your form objects.

If all this form object malarkey with Virtus gets to be too much, consider Reform. It has a similar approach, but its raison d'etre is decoupling forms from models.

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You also have an issue with your form… I'm not sure what you were hoping to achieve with the syntax you're using, but if you look at your HTML you'll see that your input names aren't going to pan out. Try something more traditional instead:

<%= f.fields_for :emails do |ff| %>
  <%= ff.text_field :email_text %>
<% end %>

With this you'll get names like user_form[emails][][email_text], which Rails will conveniently slice and dice into something like this:

user_form: { 
  emails: [
    { email_text: '...', id: '...' },
    { ... }
  ]
}

Which you can whitelist with the above solution.