Question

Problem domain

• We have Projects and Milestones
• Once created, a Milestone has a Project

Routing

In my original approach, I had something like:

  resources :projects do
    resources :milestones
  end

So all the RESTful routes looked like: projects/PROJ_ID/milestones/ID

This was getting a bit long for my liking and you don’t need the Project ID all the time: only just when you create the Milestone.

Now, the routes look like:

  resources :projects do
    resources :milestones, :only => [:new, :create]
  end

  resources :milestones, :except => [:new, :create]

When I create a new Milestone (first route):

• I use the nested resource
• This is so as to get the Project ID
• We are creating a new Milestone, we need a Project ID

With other Milestone operations (second route):

• I use standard Milestone resource
• We’re already operating on an existing Milestone
• The Milestone already carries a Project ID

Problem: Rendering __form.html.erb

All is fine, except when I get to the views for new.html.erb and edit.html.erb for Milestone. These render _form.html.erb.

Original approach (all resources nested)

<%= form_for([@project, @milestone]) do |f| %>
  ...
<% end %>

Due to nested resource, we need to have Project and Milestone as parameters.

The same code above works fine for new and edit. because the original approach assumed Project/Milestone nested routing for all REST operations.

Current approach (only create/new nested)

We want _form.html.erb to look like this when we are creating a new Milestone:

<%= form_for([@project, @milestone]) do |f| %>
  ...
<% end %>

And for all other REST operations on a Milestone, we want _form.html.erb to look like this:

<%= form_for(@milestone) do |f| %>
  ...
<% end %>

So …

Current solution is not pretty:

• View code checks if “new” or non-“new” action called it
• Use “if” test to choose which code (as above) the view should execute

It’s not DRY, it’s messy and it feels like there should be a more elegant way.

Would appreciate any input. Very much still coming up to speed with Rails. Thanks in advance 😉

Answer 1

You can pass variable with you resource to _form partial. For example:

New:

render "form", :resource => [@project, @milestone]

Edit:

render "form", :resource => @milestone

Inside the form

<%= form_for resource do |f| %>
  ...
<% end %>