Rails - May 2006 - Real life use of multiple linked models in the same view

I''m pretty new to Rails and now, in order to fully learn RoR,
I''m trying to replicate a project developed in Java using
Hibernate+Tapestry. Tapestry is based on components and you can really use
objects mappings in views like:

Example from the contact edit (view).
<input jwcid="@TextField" value="ognl:contact.name" />
<input jwcid="@TextField"
value="ognl:contact.officePhone.value" />

The same RoR code should look like:
<%= text_field ''contact'', ''name'' 
%></p>
<%= text_field ''contact[office_phone]'',
''value''  %></p>

I would preffer the patched version that should work like:
<%= text_field ''contact.office_phone'',
''value''  %></p>

Why to have other calling method than usual dot? the [] are not even permitted
by the W3C standard.
There is a patch at http://dev.rubyonrails.org/ticket/2053 but nobody seamns to
give it some credit. It''s 9 month old!!

The parameters are putted in a nested hash. The question is why the above code
doesn''t work on submission of the form.

The error reported is "Phone expected, got HashWithIndifferentAccess"

Parameters: {"commit"=>"Edit",
"id"=>"1",
"contact"=>{"office_phone"=>{"text"=>"123"},
"name"=>"same name"}}

I''m looking for a beautiful solution with some magic in it just because
I want to keep my code as clean as possible. I''ve read the most RoR
books but none seams to target medium-advanced use of RoR and this problems
it''s clear not for the beginners.


-- 
Best regards,

Sorin Sbarnea

Sorin Sbarnea wrote:
> I would preffer the patched version that should work like:
> <%= text_field ''contact.office_phone'',
''value''  %></p>
> 
> Why to have other calling method than usual dot? the [] are not even 
> permitted by the W3C standard.
They aren''t.

The [] were embraced in programming languages to auto-create associative 
arrays or hashes from flat POST data. This wasn''t proposed by W3C 
because they don''t specify what should server-side scripts do with POST
data. Why the []? Because they usually denote array or attribute 
accessors (or hashes in Ruby).

I realize this is counter-intuitive in this particular case but it''s 
very intuitive for most of the people doing various languages out there.
> There is a patch at http://dev.rubyonrails.org/ticket/2053 but nobody 
> seamns to give it some credit. It''s 9 month old!!
The patch doesn''t say nothing about ''.'' character
instead of []?
> The parameters are putted in a nested hash. The question is why the 
> above code doesn''t work on submission of the form.
> 
> The error reported is "Phone expected, got
HashWithIndifferentAccess"
Well, it''s because you are trying to save what you get from POST (or 
GET, doesn''t matter) data into an ActiveRecord association. The thing 
is, what you get from ''params'' is HashWithIndifferentAccess,
and
ActiveRecord associations expect an ActiveRecord::Base subclasses (in 
this case, the ''Phone'' model). In other words: associations
are made out
of models, so you cannot put everything into them.
> I''m looking for a beautiful solution with some magic in it just
because
> I want to keep my code as clean as possible.
What you want (POST/GET data being saved instantly into models) seems 
pretty dangerous to me. Not everything can be ''magic'', even in
Rails.
IMO, this will never be core, so the best solution for you is to take a 
few days to study Rails internals, make yourself a plugin to add 
features you need and use it in your project, even release it into 
public.

--
Mislav

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

Thanks for your reply and correct me if I''m wrong. 

What is bad if the entire HashWithIndifferentAccess is translated to model(s)?
I think that the best way is to include the security checks in any attribute=()
methods of the class and not in update_attributes method.

I think of this because controller is supposed to control the web pages and for
example if I want to create a gui or an WAP interface I would like to have the
same security rules for all controllers that edits the same model.

(By security features I mean: user x can write y attribute, and so on... almost
any kinds of constrains)

After I manage how to make rails views similar to Tapestry. I want to have
minimum code in the Controller and View so I''ll be able to develop
better models with lots of business logic in them.

I suppose I could get the desired behavior by writing a better
update_attributes(). I don''t think this would be quite simple because
the edited model can be in various forms: new records (no id), existing records
(with id) or worse combinations of the first two.

The second (#2) problem would be: how can I receive all validation messages on
the page. Let''s say that Phone.value will generate and error even if
the Person is valid.

Still looking for a good Rails FAQ - best found until now was
http://rails.techno-weenie.net and the mailling list archive (>40,000 mesages
- quite hard to find in them).

Mislav wrote:
> Sorin Sbarnea wrote:
> 
> They aren''t.
> 
> The [] were embraced in programming languages to auto-create associative 
> arrays or hashes from flat POST data. This wasn''t proposed by W3C 
> because they don''t specify what should server-side scripts do with
POST
> data. Why the []? Because they usually denote array or attribute 
> accessors (or hashes in Ruby).
> 
> I realize this is counter-intuitive in this particular case but
it''s
> very intuitive for most of the people doing various languages out there.
> 
> 
> The patch doesn''t say nothing about ''.''
character instead of []?
> 
> 
> Well, it''s because you are trying to save what you get from POST
(or
> GET, doesn''t matter) data into an ActiveRecord association. The
thing
> is, what you get from ''params'' is
HashWithIndifferentAccess, and
> ActiveRecord associations expect an ActiveRecord::Base subclasses (in 
> this case, the ''Phone'' model). In other words:
associations are made out
> of models, so you cannot put everything into them.
> 
> 
> What you want (POST/GET data being saved instantly into models) seems 
> pretty dangerous to me. Not everything can be ''magic'',
even in Rails.
> IMO, this will never be core, so the best solution for you is to take a 
> few days to study Rails internals, make yourself a plugin to add 
> features you need and use it in your project, even release it into 
> public.
> 
> --
> Mislav
>

Sorin Sbarnea wrote:
> Thanks for your reply and correct me if I''m wrong.
> 
> What is bad if the entire HashWithIndifferentAccess is translated to 
> model(s)?
Well you can make a new entry out of params, that is the translation for 
you. As you''ve noticed, that doesn''t fill in associated
models, because
it doesn''t know how. You can override the write accessors for the 
association, eg. attribute=() that takes a hash and creates a new one, 
then adds it to the association.
> The second (#2) problem would be: how can I receive all validation 
> messages on the page. Let''s say that Phone.value will generate and
error
> even if the Person is valid.
Read about the error object: 
http://api.rubyonrails.com/classes/ActiveRecord/Validations.html
> Still looking for a good Rails FAQ - best found until now was 
> http://rails.techno-weenie.net and the mailling list archive (>40,000 
> mesages - quite hard to find in them).
First, use the API, then the Wiki; if you are still confused refer to 
the list, Rails Weenie IRC and blogs (Google search). A book on the side 
can''t hurt, too ;)


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