Rails spinoffs - Nov 2007 - Getting multi-valued form values by name

Hi --

The Prototype documentation suggests the following to get form values
by name:
<code>
$F( $( formID )[fieldName] )
</code>

However the above does not work if I have multiple checkboxes or radio
buttons with the same name, since in that case $( formID )[fieldName]
returns a NodeList.  I understand the suggestion of using
Form.getInputs() however I prefer to use field names instead so that I
don''t have to worry about what type of input a particular field is.

So, I found I can solve this problem by changing
Form.Element.Methods.getValue to support taking a NodeList parameter
as well as a single argument, like so:
<code>
var old$F = Form.Element.Methods.getValue;
/* Handles multiple-valued elements for the case where form[fieldName]
 * returns multiple elements (i.e. checkboxes and radio buttons
 */
Form.Element.Methods.getValue = function(element) {
  if( element instanceof NodeList )
    return $A( element ).collect( function(e) { return
$F(e); } ).compact();
  else return old$F( element );
};
var $F = Form.Element.Methods.getValue;
</code>

I don''t purport to know anything about Prototype but this seems to
work without breaking backwards compatibility.  I also added a new
utility method to get a field value given a form and a field name:
<code>
Form.Element.Methods.getValueByName = function(form, fieldName) {
  if( form instanceof String ) form = $(form);
  return $F( form[fieldName] );
};
var $FN = Form.Element.Methods.getValueByName;
</code>

Any thoughts on why this might be a _bad_ idea?
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