Getting a strange nil in Rails with Select

I'm getting a strange nil problem with the following code.

The view (part of it):

<p>
  <%= label :maintenance, :name %>
  <%= text_field(:maintenance, :name, :size => 20) %>
</p>
<p>
  <%= label :maintenance, :type %>
  <%= select :maintenance, :type, @m_types  %>
</p>

If I remove the text_field or move it below the select, I get a nil for the :maintenance in the select.

the controller method:

def new
  @log = Log.new
  @maintenance = Maintenance.new

  @m_types = Maintenance.types
  @cars = Car.all

  print @maintenance

  if not params[:car].nil?
@log.car = params[:car]
  end

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

I'm assuming it must be some strange Ruby evaluation thing, but I have no idea what I'm 开发者_运维问答looking for. I searched around with Google, but not knowing what you're searching for makes that pretty hard.

TIA!

Thanks to all who helped out, but I refactored my models, changed my inheritance column and it works now. I think the problem was that I was using :type as the inheritance column, so when I asked to set the :type in the select before I did the text_field it didn't know I was using a Maintenance object and it was looking for a regular object. Any normal Ruby object uses the :type field for something else. So it was looking for the :type set to a module, and not to a String as I was trying to do.

You can see my new setup that's working. Hope someone can learn from this.

---

I highly suggest that you use the form_for method to declare your forms.

In your case you can do (in your view):

form_for @maintenance do |f|
  f.label :name
  f.text_field :name
end

This will attach the form variables to your instance of @maintenance.

Check out this guide for more info on forms in Rails - Dealing with Model Objects in Forms