Using javascript to get an attribute using an ID

Rails
1

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

2

On Jun 18, 2006, at 10:57 AM, Daniel H. wrote:

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

3

That did it - thanks so much!

Daniel