Beginner Error: You have a nil object

rubyonrails-talk
1

So I set out to build an app that is very similar to the Depot app to build my experience. I added a lot of constant lists for the pulldowns on the admin add product page. Then this error?

NoMethodError in Admin#new

Showing app/views/admin/_form.rhtml where line #9 raised:

You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occurred while evaluating nil.select

Extracted source (around line #9):

6: 7: <p><label for="vehicle_newused">Newused</label><br/> 8: <%= 9: form.select :newused, 10: Vehicle::NEWUSED, 11: :prompt => "New or used vehicle?" 12: %></p>

from vehicle.rb

  NEWUSED = [     ["New", "New"],     ["Used", "Used"]   ]

2

The error is related to the 'form' variable being nil, not your NEWUSED constant. So start looking there. Where is form defined?

3

I don't, I thought it was universal: form.select and form.text_field and form.text_area. Hrm. I'm assuming that I missed one of these guys: <div class="fss-form">

4

You just added a div field, which certainly doesn't do anything as far as Ruby is concerned.

You're probably missing something like

<% form_for :something, :url => some_url, do |form| %>

Take a closer look at whatever code you're copying. It'll show you exactly what you need to do.

Pat

5

Ok, you are correct. I found out the problem but that led to another problem. I'm converted a dynamic scaffold to a static and then edited the rhtml so that all of the fields wouldn't be textboxes. In this case I want a select pulldown and have two options to choose from. I just removed the form. on each one and now I've got a page with the pulldowns with one option: prompt.

6

Ok, I'm getting closer. This gives me the pull-down with NewNew in it -- I need it to be New or Used and not printed twice.

<p><label for="vehicle_newused">Newused</label><br/> <%=   select 'vehicle_newused','newused',   [Vehicle::NEWUSED]    %></p>

7

This appears to be the answer, thanks to AgileROR: <p><label for="vehicle_newused">Newused</label><br/> <%=   select (:vehicle, :newused, Vehicle::NEWUSED, :prompt => "New or used?")    %></p>