Rails - Jun 2006 - using javascript to get an attribute using an ID

Hi everyone,

I''m trying to use ajax to update the selected value of a select
element.
Here''s what I have so far:

function RailsModel(model_name)
{
  this.model_name = model_name;
}

RailsModel.prototype.getAttributeById = function(attribute, id)
{
  Ajax.Request(''/models/get_attribute_by_id/'' +
this.model_name + ''/'' +
attribute + ''/'' + id,
                {
                  onSuccess:function(response){
                    this.currentValue = response.responseText;
                  }
                }
              );
}

var model = new RailsModel(''user'');

$(''some_element'').railsModel = model;
$(''some_element'').getAttributeById(''position'',
4);


I''m not entirely sure that this works.  However, my question is, how to
I
actually load the correct model in Rails when this request is received?

The URL will be /models/get_attribute_by_id/user/position/4 - I can set up
the routing so that the params "model", "attribute", and
"id" will be set.
But how do I take the value of params[:model], which will be a string, and
use it to load the right model AND to use that model/class?

So, using a string with value of ''user'', how can I do the
equivalent of

require ''User'' #(this part isn''t that hard)
#accessing User here is the hard part
model_instance = User.find_by_id(params[:id].to_i)
render :text => model_instance.send(params[:attribute]) #Haven''t
tried this


Thanks!
Daniel

On Jun 18, 2006, at 10:57 AM, Daniel Higginbotham wrote:
>
> So, using a string with value of ''user'', how can I do the
> equivalent of
>
> require ''User'' #(this part isn''t that hard)
> #accessing User here is the hard part
> model_instance = User.find_by_id(params[:id].to_i)
> render :text => model_instance.send(params[:attribute])
#Haven''t
> tried this
>
>
> Thanks!
> Daniel

Daniel-

	How about something like this:

I don''t think you will need to require User at all:


render :text => params[:model].constantize.find(params[:id]).send 
(params[:attribute])


Cheers-
-Ezra

That did it - thanks so much!

Daniel

-----Original Message-----
From: rails-bounces@lists.rubyonrails.org
[mailto:rails-bounces@lists.rubyonrails.org] On Behalf Of Ezra Zygmuntowicz
Sent: Sunday, June 18, 2006 9:56 AM
To: rails@lists.rubyonrails.org
Subject: Re: [Rails] using javascript to get an attribute using an ID


On Jun 18, 2006, at 10:57 AM, Daniel Higginbotham wrote:
>
> So, using a string with value of ''user'', how can I do the
> equivalent of
>
> require ''User'' #(this part isn''t that hard)
> #accessing User here is the hard part
> model_instance = User.find_by_id(params[:id].to_i)
> render :text => model_instance.send(params[:attribute])
#Haven''t
> tried this
>
>
> Thanks!
> Daniel

Daniel-

	How about something like this:

I don''t think you will need to require User at all:


render :text => params[:model].constantize.find(params[:id]).send 
(params[:attribute])


Cheers-
-Ezra
_______________________________________________
Rails mailing list
Rails@lists.rubyonrails.org
http://lists.rubyonrails.org/mailman/listinfo/rails