Rails - Aug 2005 - Using form helpers with a collection of new model objects

I''m working on my first Rails project and have hit a problem that I
can''t seem to work around. Basically, I''m making an
application that
tracks access requests to various resources. When a user makes a
request they should be presented with a set of questions which all
should be answered. Those answers need to be stored along with all
other request information. I''m including my models (stripped of
validation code) as well as my request controller and a view that''s
causing my problem.

When the user selects a resource I grab all of the questions
associated with that resource and make an array of Answer objects. My
problem is this: I want to use form helpers in the view to present
those objects and then to handle the display of errors and validation
problems but the helper expects objects in a collection to have id''s
which my new, unsaved objects don''t have. Is there some way to use
form helpers with a collection of new objects that don''t have ids? It
would be nice to leverage the form helpers and Active Record models to
handle verification and error display and it seems like this would be
a common activity... I''m at the point were I feel I''m missing
something obvious. ;-)

For reference, here are the models, controller and view in concern:

app/model/resource.rb
----------------------------------
class Resource < ActiveRecord::Base
    has_and_belongs_to_many :questions
    has_many :requests
end

app/model/question.rb
----------------------------------
class Question < ActiveRecord::Base
    has_and_belongs_to_many :resources
end

app/model/answer.rb
--------------------------------
class Answer < ActiveRecord::Base
    belongs_to :request
end

app/model/request.rb
--------------------------------
class Request < ActiveRecord::Base
    belongs_to :resource
    has_many :answers
end

app/controllers/request_controller.rb
-------------------------------------------------------
class RequestController < ApplicationController
    def index
        @resources = Resource.find(:all)
    end

    def make_request
        session[:resource] ||= Resource.find(@params[:resource][:id])

        @answers = Array.new
        session[:resource].questions.each do |question|
            answer = Answer.new
            answer.question_text = question.text
            @answers << answer
        end
    end

    def complete_request
        request = Request.new
        request.resource = session[:resource]

        answers = Array.new
        @params[:answer].each do |answer|
            answer = Answer.new(answer.keys, answer.values)
            request.answers << answer
        end

        if request.save
            redirect_to_index(''Your request has been received. Expect
a reply soon!'')
        else
            flash[:notice] = ''Unable to save request''
            redirect_to(:action => ''make_request''
        end
    end
end

app/viewes/request/make_request.rhtml
--------------------------------------------------------------
<%= start_form_tag :action => ''complete_request'' %> 
<table>
    <% for @answer in @answers %>
    <tr>
        <td><%= answer.question_text %></td>
        <td><%= text_field ''answer[]'',
''text'' %></td>
    </tr>
    <% end %>
</table>
<%= submit_tag "Submit" %> 
<%= end_form_tag %> 


Thanks for any advice!

--
Ryan

Let me try distilling this down to the key question: Is there a way to
use Rails'' form helpers with a collection of new model objects? Since
the new model objects haven''t been saved they don''t have
associated
ids that the form helpers seem to expect they have. I don''t want to
save and then potentially later delete these objects, however, just to
use the form helpers.

Any suggestions? Am I going about my problem (described below...) in
the completely wrong way? I welcome any tips and criticisms!

--
Ryan

On 8/23/05, Ryan Nielsen
<rpnielsen-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> I''m working on my first Rails project and have hit a problem that
I
> can''t seem to work around. Basically, I''m making an
application that
> tracks access requests to various resources. When a user makes a
> request they should be presented with a set of questions which all
> should be answered. Those answers need to be stored along with all
> other request information. I''m including my models (stripped of
> validation code) as well as my request controller and a view
that''s
> causing my problem.
> 
> When the user selects a resource I grab all of the questions
> associated with that resource and make an array of Answer objects. My
> problem is this: I want to use form helpers in the view to present
> those objects and then to handle the display of errors and validation
> problems but the helper expects objects in a collection to have
id''s
> which my new, unsaved objects don''t have. Is there some way to use
> form helpers with a collection of new objects that don''t have ids?
It
> would be nice to leverage the form helpers and Active Record models to
> handle verification and error display and it seems like this would be
> a common activity... I''m at the point were I feel I''m
missing
> something obvious. ;-)
> 
> For reference, here are the models, controller and view in concern:
> 
> app/model/resource.rb
> ----------------------------------
> class Resource < ActiveRecord::Base
>     has_and_belongs_to_many :questions
>     has_many :requests
> end
> 
> app/model/question.rb
> ----------------------------------
> class Question < ActiveRecord::Base
>     has_and_belongs_to_many :resources
> end
> 
> app/model/answer.rb
> --------------------------------
> class Answer < ActiveRecord::Base
>     belongs_to :request
> end
> 
> app/model/request.rb
> --------------------------------
> class Request < ActiveRecord::Base
>     belongs_to :resource
>     has_many :answers
> end
> 
> app/controllers/request_controller.rb
> -------------------------------------------------------
> class RequestController < ApplicationController
>     def index
>         @resources = Resource.find(:all)
>     end
> 
>     def make_request
>         session[:resource] ||= Resource.find(@params[:resource][:id])
> 
>         @answers = Array.new
>         session[:resource].questions.each do |question|
>             answer = Answer.new
>             answer.question_text = question.text
>             @answers << answer
>         end
>     end
> 
>     def complete_request
>         request = Request.new
>         request.resource = session[:resource]
> 
>         answers = Array.new
>         @params[:answer].each do |answer|
>             answer = Answer.new(answer.keys, answer.values)
>             request.answers << answer
>         end
> 
>         if request.save
>             redirect_to_index(''Your request has been received.
Expect
> a reply soon!'')
>         else
>             flash[:notice] = ''Unable to save request''
>             redirect_to(:action => ''make_request''
>         end
>     end
> end
> 
> app/viewes/request/make_request.rhtml
> --------------------------------------------------------------
> <%= start_form_tag :action => ''complete_request''
%>
> <table>
>     <% for @answer in @answers %>
>     <tr>
>         <td><%= answer.question_text %></td>
>         <td><%= text_field ''answer[]'',
''text'' %></td>
>     </tr>
>     <% end %>
> </table>
> <%= submit_tag "Submit" %>
> <%= end_form_tag %>
> 
> 
> Thanks for any advice!
> 
> --
> Ryan
>