validates_presence_of not working properly...how to debug? - ruby-on-rails

Question

In my Review model, I have the following:
class Review < ActiveRecord::Base
belongs_to :vendor
belongs_to :user
has_many :votes
validates_presence_of :summary
end
I submit a new entry as follows in the URL:
vendors/9/reviews/new
The new.html.erb contains a form as follows:
<%= error_messages_for 'review' %>
<h1>New review for <%= link_to #vendor.name, #vendor%></h1>
<% form_for(#review, :url =>vendor_reviews_path(#vendor.id)) do |f| %>
<%= f.error_messages %>
<p>
<%= f.label :summary %><br />
<%= f.text_area :summary, :rows=>'3', :class=>'input_summary' %>
<%= f.hidden_field :vendor_id, :value => #vendor.id %>
</p>
<p>
<%= f.submit 'Submit Review' %>
</p>
<% end %>
When I leave the field for :summary blank, I get an error, not a validation message:
You have a nil object when you didn't expect it!
The error occurred while evaluating nil.name
Extracted source (around line #3):
1: <%= error_messages_for 'review' %>
2:
3: <h1>New review for <%= link_to #vendor.name, #vendor%></h1>
I don't understand what is happening, it works if :summary is populated
def new
#review = Review.new
#vendor = Vendor.find(params[:vendor_id])
#review = #vendor.reviews.build
respond_to do |format|
format.html # new.html.erb
format.xml { render :xml => #review }
end
end
def create
#review = Review.new(params[:review])
##vendor = Vendor.find(params[:vendor_id]) #instantiate the vendor from the URL id -- NOT WOKRING
##review = #vendor.reviews.build #build a review with vendor_id -- NOT working
#review = #current_user.reviews.build params[:review]#build a review with the current_user id
respond_to do |format|
if #review.save
flash[:notice] = 'Review was successfully created.'
format.html { redirect_to review_path(#review) }
format.xml { render :xml => #review, :status => :created, :location => #review }
else
format.html { redirect_to new_review_path(#review) }
format.xml { render :xml => #review.errors, :status => :unprocessable_entity }
end
end
end
My guess is that when it fails it is going to redirect_to new_review_path(#review) and so doesn't know the vendor it. How can I redirect to vendor/:vendor_id/reviews/new instead?

Answer 1

You probably don't have #vendor member variable set - but to fix this, it would be more correct to use not #vendor directly, but through your #review variable instance.
If you are creating new review, you already have #review member variable created, and you simply are populating fields in it - so, you need to set the vendor for #review (unless it's optional)... it would be more correct to use #review.vendor.name instead.
(If vendor is optional, then you obviously must catch all vendor.nil? cases.)

Answer 2

What code do you have in the new and create actions in your ReviewsController?
I suspect that your new Review is failing validation because the summary field is blank and then when the form is redisplayed on validation failure, the #vendor instance variable is nil.
You need to make sure that #vendor is assigned a value for both code paths.

Answer 3

I think you need to render :action => 'new' instead of your redirect_to new_review_path(#review). This will keep your error_messages on the #review object. By redirecting you are losing the old object and creating a new one.
As others has said, you also need to make sure you re-populate the #vender variable in your create method before rendering the view.
PS. I like to use the ardes resources_controller plugin for bog standard controller actions like these, makes life a lot easier for me and it handles nested resources really well.