Re: [Rails] Re: accepts_nested_attributes_for doesn't show output

[Jen]

Hi,
After getting nowhere I decided to follow this article:
http://ryandaigle.com/articles/2009/2/1/what-s-new-in-edge-rails-nested-attributes

This meant replicating some already existing fields in my 
universities/_form, but I felt it would atleast rule out the possibility 
I was doing something silly with partials. Now I am receiving the 
following error:

NoMethodError in Universities#new

Showing 
/home/resource_portal/website/app/views/universities/_form.html.erb 
where line #26 raised:

undefined method `fields_for' for nil:NilClass

Extracted source (around line #26):

23: <%= f.label :country %><br />
24: <%= f.text_field :country %>
25: </div>
26: <%= form.fields_for :resources do |resource| %>
27: <%= f.label :resource_type %><br />
28: <%= f.text_field :resource_type %>
29: </div>

Trace of template inclusion: app/views/universities/new.html.erb

Rails.root: /home/resource_portal/website
Application Trace | Framework Trace | Full Trace

rake-0.8.7/ruby/1.9.1/gems/activesupport-3.0.3/lib/active_support/whiny_nil.rb:48:in 
`method_missing'

My code for the models, universities controller and view is attached. 
Can someone please point out what I am doing wrong? I have read many 
articles, posts and have tried many variations to achieve this. Do I 
need to set @resources and @universities to equal some value before 
rendering the form?

Code for controller:

class UniversitiesController < ApplicationController
#insure users are signed in before viewing these pages
before_filter :authenticate

  # GET /universities
  # GET /universities.xml
  def index
    @universities = University.all

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

  # GET /universities/1
  # GET /universities/1.xml
  def show
    @university = University.find(params[:id])

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

  # GET /universities/new
  # GET /universities/new.xml
  def new
    @university = University.new
@resource = @university.resources.build
    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @university }

    end
  end

  # GET /universities/1/edit
  def edit
    @university = University.find(params[:id])
  end

  # POST /universities
  # POST /universities.xml
  def create
    @university = University.new(params[:university])

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

  # PUT /universities/1
  # PUT /universities/1.xml
  def update
    @university = University.find(params[:id])

    respond_to do |format|
      if @university.update_attributes(params[:university])
        format.html { redirect_to(@university, :notice => 'University 
was successfully updated.') }
        format.xml  { head :ok }
      else
        format.html { render :action => "edit" }
        format.xml  { render :xml => @university.errors, :status => 
:unprocessable_entity }
      end
    end
  end

  # DELETE /universities/1
  # DELETE /universities/1.xml
  def destroy
    @university = University.find(params[:id])
    @university.destroy

    respond_to do |format|
      format.html { redirect_to(universities_url) }
      format.xml  { head :ok }
    end
  end
end

Code for models:

class University < ActiveRecord::Base
has_many :resources
accepts_nested_attributes_for :resources, :allow_destroy => :true,
    :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } }
attr_accessible :resource_attributes
end

class Resource < ActiveRecord::Base
#Defines the relationship between resource and user.
belongs_to :user
belongs_to :university
attr_accessible :resource_type, :subject, :author, :course, 
:alternative_use,
#Need to add some more validation to the fields.
def self.search(search)
  if search
    find(:all, :conditions => ['subject LIKE ?', "%#{search}%"])
#Join tables here

  else
    find(:all)
  end
end
#End class.
end

Code for views:

<%= form_for(@university) do |f| %>
<% if @university.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(@university.errors.count, "error") %> prohibited this 
university from being saved:</h2>

<ul>
<% @university.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>

<div class="field">
<%= f.label :name %><br />
<%= f.text_field :name %>
</div>
<div class="field">
<%= f.label :address %><br />
<%= f.text_field :address %>
</div>
<div class="field">
<%= f.label :country %><br />
<%= f.text_field :country %>
</div>
<%= form.fields_for :resources do |resource| %>
<%= f.label :resource_type %><br />
<%= f.text_field :resource_type %>
</div>
<% end %>
<div class="actions">
<%= f.submit %>
</div>
<% end %>

<h1>New university</h1>

<%= render 'form' %>
<ul>
<li> <%= link_to 'Back', universities_path %> </li>
</ul>

Thanks in advance for any further assistance,
Jen.
On 21/07/11 12:11, Colin Law wrote:
On 21 July 2011 11:55, Jen<jen.bot...@gmail.com>  wrote:

Please don't top post, it makes it difficult to follow the thread.
Insert your reply at appropriate point(s) in previous post.  Thanks.

Hi Colin,
I can't see anything in my controller that indicates I have set @resource to
nil.
When I go directly to the resources form it renders fine and I can add data
about new resources. It's just when trying to render the form as a partial
within the universities/_form view.
I had missed the fact that you were in a partial.  Have a look at the
Rails Guide on Layouts and Rendering, specifically the section on
using partials and passing values to it.

If you have not already done so, also have a good look the other
guides, it will be time well spent.


Colin

Do I need to add something in the 'universities_controller' that gives
@resource a value. Perhaps '@resource = Resource.new'?

Below is the code from the 'universities_controller' so far:

class UniversitiesController<  ApplicationController
#insure users are signed in before viewing these pages
before_filter :authenticate

  # GET /universities
  # GET /universities.xml
  def index
    @universities = University.all

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

  # GET /universities/1
  # GET /universities/1.xml
  def show
    @university = University.find(params[:id])

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

  # GET /universities/new
  # GET /universities/new.xml
  def new
    @university = University.new

    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml =>  @university }
resource = @university.resources.build

    end
  end

  # GET /universities/1/edit
  def edit
    @university = University.find(params[:id])
  end

  # POST /universities
  # POST /universities.xml
  def create
    @university = University.new(params[:university])

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

  # PUT /universities/1
  # PUT /universities/1.xml
  def update
    @university = University.find(params[:id])

    respond_to do |format|
      if @university.update_attributes(params[:university])
        format.html { redirect_to(@university, :notice =>  'University was
successfully updated.') }
        format.xml  { head :ok }
      else
        format.html { render :action =>  "edit" }
        format.xml  { render :xml =>  @university.errors, :status =>
:unprocessable_entity }
      end
    end
  end

  # DELETE /universities/1
  # DELETE /universities/1.xml
  def destroy
    @university = University.find(params[:id])
    @university.destroy

    respond_to do |format|
      format.html { redirect_to(universities_url) }
      format.xml  { head :ok }
    end
  end
end

Thanks,
Jen.

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