Redirects with Datamapper & Rails

Question

I have a line in my routes.rb to map my Album model as a resource:

  map.resources :albums

However, using Datamapper in place of ActiveRecord in Rails, why would this line:

format.html { redirect_to(@album) }

cause a redirect to:

albums/%23<Album:0x72d452c>

instead of:

albums/1

In case further context is needed, my full create method from the Controller is listed here:

  def create
    @album = Album.new(params[:album])

    respond_to do |format|
      if @album.save
        flash[:notice] = 'Album was successfully created.'
        format.html { redirect_to(@album) }
        format.xml  { render :xml => @album, :status => :created, :location => @album }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @album.errors, :status => :unprocessable_entity }
      end
    end
  end

As is convention, this method is invoked as a result of a form submission from my 'new' method in the new.html.erb:

<h1>New album</h1>

<% form_for(@album) do |f| %>

  <p>
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </p>
  <p>
    <%= f.label :description %><br />
    <%= f.text_field :description %>
  </p>
  <p>
    <%= f.label :genre %><br />
    <%= f.text_field :genre %>
  </p>
  <p>
    <%= f.label :country %><br />
    <%= f.text_field :country %>
  </p>
  <p>
    <%= f.submit 'Create' %>
  </p>
<% end %>

<%= link_to 'Back', albums_path %>

Answer 1

Does Datamapper support a to_param method or have you implemented one on your Album model? Until we have Rails 3 and an "ActiveORM" layer to cover up the differences between ORMs, you have to make sure your code conforms to an AR-like API.

If there is a to_param method and this still doesn't work, try doing it the old fashioned way:

format.html { redirect_to(album_path(@album.id)) }

Clunkier but most likely effective.