[Instantrails-developers] RESOLVED - Assistance needed
bill.walton at charter.net
Fri Jun 30 12:24:21 EDT 2006
David Morton wrote:
> I don't see what the bug is.
I'm still doing a bit of research to determine whether or not to call this a
bug. I hope you'll understand that this response is not intended to be
confrontational. I intend it to be conversational and would be interested
in your thoughts re: my thoughts below.
> How is a function supposed to work on a particular
> element if there are two elements with the same name?
> If I submit a form with two inputs both named "username"
> I wouldn't expect it to work...
The DOM is a hierarchy. The limitation on uniqueness is, as I understand
it, intended to be at the container level. If you could point me to a spec
that says otherwise (i.e., that specifically says that all DOM names have to
be unique across the DOM), I'll definitely call off my inquiry. Just coming
at it from a less-than-completely-informed position, however, I can have two
forms on the same page, each one having a :name field, without causing any
problem. No? Why would different rules apply to it than to the DOM
elements inside it?
> In the case of observe_field, I think it is looking
> for a DOM element with the specified name,
I understand that that's what observe_field is doing. The question I'm
currently looking at boils down to what it *could* be doing. A couple of
things seem to me to be relevant to that question.
First, it seems to me, at this point, that the root of the problem lies in
the implementation/specification of getElementById("elementID"). In
than one instance of an ID, the method returns a reference to the first
element in source code order with that ID." OK. But, given the object
hierarchy, why's it taking such a lame approach to the request. At a
minimum, it seems to me we should be able to give getElementById an
xPath-type name to uniquely identify the element we're asking about. On a
slightly different tack, getElementByName returns an array. Why shouldn't
Secondly, once we have an element we have access to a whole bunch of
property information about it that we could use to determine if it's the one
we're looking for. In the case of observe_field, it seems odd to me that it
would throw-up over encountering a <div> with the same name as something
it's being asked to observe. AFAIK, a <div> is not something observe_field
would be observing. So why couldn't it continue looking for another DOM
element with that same name that would be an appropriate target?
> Oh, another debugging tip. Any time you get a
> "undefined method" error, it probably means that the
> object it is trying to do that method on is not what you
> think; so the best bet is to go back to where it is assigned
> and see what the object actually is.
Thanks for the tip. I'm definitely accruing them in my 'lessons learned'
More information about the Instantrails-developers