Question

RoR is famous for being “convention over configuration”, so it’s likely that my question is off — I don’t know the convention I should be following.

I have 2 model objects, ParseException and ParseResolution, and ParseResolution belongs_to ParseException.

I am simply making an admin panel off of the Rails scaffolding, and I want to add a new ParseResolution object, tied to a ParseException object.

After generating controllers for both models, I added a link to parse_resolution/new from parse_exception/index. Since ParseResolution needs to know which ParseException it is resolving (belongs_to), I am also passing it as a parameter:

<td><%= link_to 'Add Resolution', new_parse_resolution_path(:parse_exception => parse_exception) %></td>

So far so good.

In my ParseResolution controller, I have:

def new
  @parse_resolution = ParseResolution.new
  @parse_resolution.parse_exception = ParseException.find(params[:parse_exception])

  respond_to do |format|
    format.html # new.html.erb
    format.xml  { render :xml => @parse_resolution }
  end
end

So far so good, as I can access the ParseException object inside my ERB file and display its details.

However, when I press the “Create” button to add my new ParseResolution object, the save method complains that I’m not providing it with a ParseException, which is a required column.

I tried doing this with a hidden_field:

<%= hidden_field(:parse_resolution, :parse_exception) %>

But that just converts the actual ParseException object into a string:

<input id="parse_resolution_parse_exception" name="parse_resolution[parse_exception]" type="hidden" value="#&lt;ParseException:0x1108a8930&gt;" />

Which clearly won’t work.

OK, so I’m trying again not to hate Ruby on Rails for all of its voodoo-like convention. Would someone please enlighten me on the best way to do what I am trying to do?

Answer 1

If you want follow good practices, you should do something like this:

Your routes to new,create,destroy action should looks like:

parse_exceptions/:parse_exception_id/parse_resolutions/new

in routes.rb it gonna be:

  resources :parse_exceptions do
    resources :parse_resolutions
  end

and then your path to new action should be something like that:

new_parse_exception_parse_resolution_path(@parse_exception)

(you also need to change path to create action in form)

Then in your ParseResolutionsController:

before_filter :load_parse_exception
.
def new
  @parse_resolution = @parse_exception.parse_resolutions.new
end

def create
  @parse_resolution = @parse_exception.parse_resolutions.new(params[:parse_collection]
  .
  .
end
private
def load_parse_exception
  @parse_exception = ParseException.find params[:parse_exception_id]
end