Question

I’m trying to build a rails form that will pass a local variable back to a controller, using a collection_select call, and am generating errors that I can’t for the life of me work out.

The form is in the Network#new view. The collection_select should create a drop down menu of existing superusers, so the new network can be assigned a superuser (via a superuser_id) on creation. The Network#create method knows how to deal with the superuser_id. So my form looks like this:

<%= form_for(@network) do |f| %>
  <%=render(partial: 'edit_form', locals: {f: f} ) %>

  <% fields_for 'superuser_id', url: {action: :create} do |su| %>
    <div>
      <%= su.label 'Network Superuser' %>
      <%= su.collection_select( 'superuser_id',@superusers, :id, :user_name)  %>
    </div>
  <% end %>

  <div>
    <%= f.submit %>
  </div>

The error I get is:

ActionView::Template::Error (undefined method `superuser_id' for {:url=>{:action=>:create}}:Hash):
6:   <% fields_for 'superuser_id', url: {action: :create}  do |su| %>
7:      <div>
8:        <%= su.label 'Network Superuser' %>
9:        <%= su.collection_select( 'superuser_id', @superusers, :id, :user_name)  %>
app/views/networks/new.html.erb:9:in `block (2 levels) in _app_views_networks_new_html_erb__687644901_79475060'

Any ideas where I am going wrong?

Thanks

Steve

Answer 1

fields_for is designed to handle a sub form of a relationship, and so it is usually used like fields_for :supervisor without the _id. However, it looks like this is a :belongs_to relationship, and fields_for is completely unneeded. You aren’t trying to create a form to edit the attributes of the supersuser, you are only assigning an existing id to the network object.

Try: <%= f.collection_select( 'superuser_id',@superusers, :id, :user_name) %> without the fields_for block