Rails - Jul 2006 - has_one, belongs_to - I am just not getting it

Let me preface by saying i''m a total noob at ruby/rails. :-)
For some reason, I am just not grasping the concept of has_one & 
belongs_to...

I''m working on a project that includes user authentication, and 3 
different types of user profiles.

User profiles are either "fan", "band", or "venue"
objects, and user
logins are "user" objects.

Just working with the "fan" profiles now.

I have the following tables:
table fans:
id
name
url
...
(etc)
...
user_id (foreign key)

table users:
id
login
hashed_password
email
salt
created_at

In User model:
class User < ActiveRecord::Base
  has_one :fan

In Fan model:
class Fan < ActiveRecord::Base
  belongs_to :user

in user_controller.rb:
    def signup
      @user = User.new(@params[:user])
      if request.post?
        if @user.save
          session[:user] = User.authenticate(@user.login, 
@user.password)
          flash[:message] = "Signup successful"
          redirect_to :controller => ''fan'', :action =>
"new"
        else
          flash[:warning] = "Signup unsuccessful"
        end
      end
    end

In fan_controller.rb:
  def new
    @fan = Fan.new
  end

  def create
    @fan = Fan.new(params[:id])
    @user.fan << @fan
    if @fan.save
      flash[:notice] = ''Your Fan Profile was successfully
created.''
      redirect_to :action => ''list''
    else
      render :action => ''new''
    end
  end

The goal is, when a new user signs up, after creating their login info, 
they get to create their "fan" profile, and when it is saved, the 
profile is saved in the fans table, with the appropriate user_id 
assigned to it.

As I currently have it, the user signup works, then takes me to the new 
profile form, but when I try to save, I get:
NoMethodError in FanController#create

You have a nil object when you didn''t expect it!
The error occured while evaluating nil.fan

RAILS_ROOT: script/../config/..
Application Trace | Framework Trace | Full Trace

#{RAILS_ROOT}/app/controllers/fan_controller.rb:28:in `create''

line 28 is ''@user.fan << @fan''

i''ve tried @user.fan = @fan, that doesn''t work...

I keep reading and reading about this, and I just can''t seem to get a 
handle on it yet. I''m in dire need of help!

much obliged,
Chad



-- 
Posted via http://www.ruby-forum.com/.

>   def create
>     @fan = Fan.new(params[:id])
>     @user.fan << @fan
>     if @fan.save
>       flash[:notice] = ''Your Fan Profile was successfully
created.''
>       redirect_to :action => ''list''
>     else
>       render :action => ''new''
>     end
>   end

you didn''t define @user.

def create
@user = User.find(..whicheveroneyouwant..) OR
@user = User.find(params[:id]) OR
@user = User.find_by_some_column(value) OR
...

@fan = Fan.new...
..
end

i reccomended you should do some tutorial to help you out; have you 
tried four days on rails? or the pragmatic store self-tutorial? these 
are great books and will give you a great base to jump off of.

anyway, i hope that helps you out.

-- 
Posted via http://www.ruby-forum.com/.

On Thu, 6 Jul 2006, Chad Wells wrote:
> In fan_controller.rb:
>  def new
>    @fan = Fan.new
>  end
>
>  def create
>    @fan = Fan.new(params[:id])
>    @user.fan << @fan
>    if @fan.save
>      flash[:notice] = ''Your Fan Profile was successfully
created.''
>      redirect_to :action => ''list''
>    else
>      render :action => ''new''
>    end
>  end
>
> The goal is, when a new user signs up, after creating their login info,
> they get to create their "fan" profile, and when it is saved, the
> profile is saved in the fans table, with the appropriate user_id
> assigned to it.
>
> As I currently have it, the user signup works, then takes me to the new
> profile form, but when I try to save, I get:
> NoMethodError in FanController#create
>
> You have a nil object when you didn''t expect it!
> The error occured while evaluating nil.fan
Instance variables only survive for the duration of one action, which
may include a "render" but not a "redirect" (that''s
a new action).  So
in create, you never initialize @user -- so it''s nil.

I have a feeling that what you really want is something like:

   def create
     @user = User.find(params[:id])
     @fan = Fan.create(params[:fan])
     @user.fan = @fan
   # etc.

Doing Fan.new(params[:id]) doesn''t make sense, since if it''s
new, it
will get assigned an id automatically, and if you''re looking it up by
id, you''d use "find".


David

-- 
  "To fully realize the potential of Rails, it''s crucial that you
take
    the time to fully understand Ruby--and with "Ruby for Rails" David
       has provided just what you need to help you achieve that goal."
       -- DAVID HEINEMEIER HANSSON, in the foreword to RUBY FOR RAILS.
  Complete foreword & sample chapters at http://www.manning.com/black!

unknown wrote:
> Instance variables only survive for the duration of one action, which
> may include a "render" but not a "redirect"
(that''s a new action).  So
> in create, you never initialize @user -- so it''s nil.
> 
I think this is my main problem! I guess I just didn''t realize this
fact. This makes sense as to why I was having so many other little
problems.

Thank you so much!

Another question, is there a way to keep an instance variable alive for
a total session, instead of having to intialize it over and over?

-- 
Posted via http://www.ruby-forum.com/.

On Jul 6, 2006, at 6:16 AM, Chad Wells wrote:
> Another question, is there a way to keep an instance variable alive  
> for
> a total session, instead of having to intialize it over and over?
That''s what session is for:

   session[:key] = @blah

and in a subsequent request:

   @blah = session[:key]

On caveat: Don''t store an ActiveRecord in the session. Instead store  
it''s
id and refetch it the next time, unless it''s you absolutely KNOW that
it
won''t change.

-- 
-- Tom Mornini