| Re: form & lookup columns [message #172370 is a reply to message #172366] |
Mon, 14 February 2011 13:06   |
sheldonlg
Messages: 166
Registered: September 2010
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Senior Member |
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On 2/14/2011 7:11 AM, Tim Streater wrote:
> In article <ijb1id$bq3$1(at)news(dot)albasani(dot)net>,
> The Natural Philosopher <tnp(at)invalid(dot)invalid> wrote:
>
>> Wolf wrote:
>>> Thanks a lot for your suggestion; have you got some links with
>>> examples of this solution?
>>
>> which one?
>>
>> Iframes - there probably are solutions out there. I dunno.
>>
>> Javascript? its a question of replicating a lot of SQL style stuff in
>> javascript and no I have no examples. Took me long enough to write a
>> much less complex version of this myself.
>>
>> The approach I followed was to have EVERY POSSIBLE screen loaded, and
>> hide everything except the starting point, and unhide the bits that
>> became relevant as selections were made. In my case it was a giant
>> flyout menu system, so my event triggers were onmouseover events. In
>> your case you probably want to use onselect() events or onclick()..
>
> Use ajax as I just posted.
>
>> Really you are building a custom web page without the convenience of
>> form input elements, if you go this route.
>>
>> And RELYING 100% on javascript being enabled.
>
> Of course it will need to be enabled. I'm always amused by people saying
> make your page work without JS.
>
>> However to do this seamlessly without the user actually pressing a
>> button, you will have to use some form of javascript event handler,
>> even if its as crude as an onselect.. to trigger either javsacript
>> driven page reformat, or a partial reload of the page.
>>
>> What iframes allow, is that partial reload into an area of the page
>> without reloading the whole page, which means you can do a mini form
>> submit of a part of a form to allow the server to dish up the clever
>> stuff.
>
> True but see my other post.
>
>> You still have to trigger that somehow, though, and I am not enough of
>> a guru to say whether or not that can happen without some sort of
>> javascript.
>
> "No" is the answer.
>
>> I think the main point to make is that this is a very big task
>> indeed..days if not weeks, of work. Not a quick cut and paste of some
>> crib code.
>>
>> And will require you to acquire some pretty in depth knowledge of bits
>> of javascript, the DOM and the way server and client side languages
>> work, to get it done.
>
> This is all true. It's quite a big task if you don't have much experience.
>
Absolutely AJAX! It is not such a big deal. There are links out there
with sample code to do the send and to process the receive.
For the OP:
It basically works like this:
1 - The selection of the region invokes a JS call.
2 - That call sets up a listener and sends an asynchronous message to
the server where the php file it calls does a db search for the provinces.
That file also creates a message that it sends back to the listener.
3 - The listener receives the message in JS and processes it creating
the proper HTML.
Google for some examples. What I did when I learned it was to set up my
own general purposes modifications from that code I found and now I use
it as a sort or library whenever I need to use AJAX.
Of course what Tim says is quite true. If you are the beginning stages
of programming, it will take a bit to understand the concept of this
kind of programming.
Without JS, just forget it.
--
Shelly
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