Error Handling Multi-Model Form - ruby-on-rails

Question

I have a multi-model form and I cannot seem to capture the errors related to the nested models. This is the hierarchy of the form Project->Team->Roles->Role_skill_relationship. I am able to capture errors related the project model instance #project but I have been unsuccessful at capturing validations related to the Role and Skills models. The errors are directly returned in the browser page rather than redirecting and flashing to the screen. One example of an error if I intentionally fill out a role portion of the form incorrectly is
NoMethodError in Roles#create
Showing
C:/Users/Dstile/Documents/GitHub/creunity_app/app/views/skills/_form.html.erb
where line #8 raised:
undefined method `map' for nil:NilClass Extracted source (around line #8)
7: <%= skill_form.label :skill %>
8: <%= skill_form.collection_select :skill_id, #skills, :id, :name, :prompt => "Select a > skill" %>
Here is a portion of the code
<%= render 'shared/project_error_messages' %>
<%= project_form.label :title %>
<%= project_form.text_field :title %>
<%= project_form.label :category, "Category" %>
<%= project_form.select(:category, Project::CATEGORY_TYPES) %>
<%= project_form.label :description %>
<%= project_form.text_area :description %>
<%= project_form.label :goal_1, "Goal 1:" %>
<%= project_form.text_field :goal_1 %>
<h2>Your Team</h2>
<%= project_form.fields_for :team do |f| %>
<%= render 'teams/form', :team_form => f %>
<% end %>`
Here is the error render code
'<% if #project.errors.any? %>
<div id="error_explanation">
<div class="alert alert-error">
The form contains <%= pluralize(#project.errors.count, "error") %>.
</div>
<ul>
<% #project.errors.full_messages.each do |msg| %>
<li>* <%= msg %></li>
<% end %>
</ul>
</div>
<% end %>'
The role form is nested within the team form in the same manner team is nested in project. From all of the other threads I have read my understanding is that the errors for project and all of its children models (team, roles, role_skill_relationships) should be captured by the #parent object.
Is there a config setting or piece of code I am missing that should force the browser to ignore the errors? My thinking is that the errors may be in #project but that this process is interrupted.

Answer 1

It appears #skills has not been set. #collection_select runs #map on the passed-in collection (#skills in this case), and will show that error if the collection is nil (which is the default value for undefined instance variables).
Remember that, in the case of validation errors, the #create method in your controller will simply be rendering a template - it does not run the corresponding action method for that template. So if you're defining #skills in your #new action, then you need to also define it in your #create action (or, better yet, in a before_filter).