Rails - May 2005 - Help with Form Helper

Hello,

Is there a way to use related objects within Form Helpers? Right now I
have an Application object that belongs_to a User. I''d like to do
something like:

<%= text_field("application.user", "first_name") %>

When I try this, I get the error "''@application.user'' is
not allowed as
an instance variable name". So my question is this, can the user object
be assigned into the Form Helper without manually assigning them to
instance variables inside the controller first?

Thanks for the help,

-- 
DeLynn Berry
delynnb-+9FQAZFMD0vCste6SmUHRhL4W9x8LtSr@public.gmane.org

My current method, but I''m rather new to rails,
is to add inside the controller using a begin_filter
thereby isolating it to one line...

if there is a better solution, i dont know about it but I''d love to
hear it.


DeLynn Berry wrote:
>Hello,
>
>Is there a way to use related objects within Form Helpers? Right now I
>have an Application object that belongs_to a User. I''d like to do
>something like:
>
><%= text_field("application.user", "first_name")
%>
>
>When I try this, I get the error "''@application.user''
is not allowed as
>an instance variable name". So my question is this, can the user object
>be assigned into the Form Helper without manually assigning them to
>instance variables inside the controller first?
>
>Thanks for the help,
>
>  
>


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"DeLynn Berry"
<delynnb-+9FQAZFMD0vCste6SmUHRhL4W9x8LtSr@public.gmane.org> writes:
> <%= text_field("application.user", "first_name")
%>
I think you could do <%= test_field("user", "first_name")
%> and then
in the controller just instantiate a user
User.new(@params[''user'']).  Once you have a valid user you can
assign
the application.user = user.
-- 
doug-jGAhs73c5XxeoWH0uzbU5w@public.gmane.org

I posted a question a couple of weeks ago about this same issue and 
didn''t get a response, I think it would be a worthy feature though it 
could be vulnerable to tampering if proper precautions aren''t being
used
if you expose your entire model.

In the webwork2 mvc framework for java this can be used, and I believe 
Spring-mvc can also do this, just pass in 
user.billingInfo.address.street, etc..
was expecting rails to behave similarly in rails using something like 
user[billingInfo][address][street]

Doug Alcorn wrote:
>"DeLynn Berry"
<delynnb-+9FQAZFMD0vCste6SmUHRhL4W9x8LtSr@public.gmane.org> writes:
>
>  
>
>><%= text_field("application.user", "first_name")
%>
>>    
>>
>
>I think you could do <%= test_field("user",
"first_name") %> and then
>in the controller just instantiate a user
>User.new(@params[''user'']).  Once you have a valid user you
can assign
>the application.user = user.
>  
>

Francisco Hernandez <lagcisco-b7MHZcQsHeJWk0Htik3J/w@public.gmane.org>
writes:
> In the webwork2 mvc framework for java this can be used, and I believe 
> Spring-mvc can also do this, just pass in 
> user.billingInfo.address.street, etc..
> was expecting rails to behave similarly in rails using something like 
> user[billingInfo][address][street]
When you call update_attributes, the model will call attribute= for
anything that''s in the parameter hash.  So:

 billing = BillingInfo.new
 billing.update_attributes({address_street => "123 Anystreet"}) 

will in turn call BillingInfo#address_street=.  It doesn''t matter if
 address_street is an attribute or not; just whether BillingInfo has
 an address_street= method.

I''m exactly sure how to leverage this to get associations updated with
form helpers though.  Here''s what I''ve done, but I''m
not sure if it''s
the best solution.

class Hobby < ActiveRecord::Base
end

Class MemberProfile < ActiveRecord::Base
  has_and_belongs_to_many :hobbies, :uniq => true

  def hobbies_ids=(list)
    hobbies.clear
    hobbies << list.collect { |o| Hobby.find(o) }
  end
end

and then in the view I have:

<% Hobby.option_list.each do |o| %>
   <% name = o.first; id = o.last %>
   <input type="checkbox" id="<%= id %>"
name="member_profile[hobbies_ids][]" value="<%= id %>"
          <% if @member_profile.hobby_by_name?(name) %>
checked="checked" <% end %> /><%= name %>
<% end  %></p>

That gives my controller a list of ids as strings in
@params[''member_profile''][''hobbies_ids'']. 
When my controller calls
@member_profile.update_attributes(@params[''member_profile''])
the
hobbies_ids= method converts that list of string ids into a list of
objects.

I definitely think we need more examples of how to update associations
on the wiki.
-- 
doug-jGAhs73c5XxeoWH0uzbU5w@public.gmane.org