Country/State/City drop down lists again

[Anon]

Hi there,

I have implemented the script from <http://www.zend.com/zend/tut/drop-down.php> but did not foresee the BIG problem that I am now faced with !!!

The above script loads ALL of the data into the javascript before the page is displayed for the first time. Forgetting for the moment that I still need to include the countries table etc. .... I have a table with 51 states and my second table has just over 26000 towns/cities in it thus the code execution time is around 45seconds which I could still live with but the resulting page which the browser loads is OVER 3MB in size!!! I do not know how large the page actually is because my browser crashes out before the page is finished loading 🙂

What I need is a script similar to the one above BUT it should ONLY go and fetch the required info once the first option is selected. It would be easy enough if I reload the page but I'd really rather not have to do that!

ie. When the page loads it should populate the STATE drop down list only, the person then selects say "Georgia" and the script then goes to fetch the towns in the second table which match "GA" and populates the second listbox with those values.

If anyone has any bright ideas or suggestions here I would really like to hear them!

BTW: Anyone able to solve my problem for me would be welcome to my Country, US States, and US Towns (by state) tables. Creating these took lots of hard work so I'm hoping someone will take the bait. LOL

Thanx
Grant

[Anon]

You can't do it.

If you want to filter the cities by state on the client side, then you just have to download everything to begin with. As you say, this will be unmanageably huge.

If you want the server to only send the towns appropriate for a selected state, then you have to break your form up over a number of pages. You can do this sequentially or in parallel.

Sequentially, the user selects the state and the form either autosubmits or the user clicks "Continue". Either way, the City dropdown list is populated for the selected state. The State dropdown can reappear on this page if required so that the user doesn't have to use the back button if they accidentally click the wrong state.

You could also do in this in parallel, using frames. Load the States dropdown list into one frame. This dropdown autosubmits, sending the output to the next frame. This frame contains the correct Cities dropdown and has the State coded as a hidden field. Any other inputs can also be managed on this second frame.

The second is probably the neatest option, but you must consider all of the usual arguments against frames.

Cheers,

Jack
[e-mail]

[Anon]

Thanx Jack,

DAMN ... I knew I was chancing my arm when I asked the question ... sigh

[doormat]

I think it might actually be possible, but in a limited way - it would impact cross-browser compatibility.

IE3+, Netscape 4.7+ (probably) and Opera 4+ support them to one degree or another, so its really up to you - for info, visit http://www.cs.tut.fi/~jkorpela/html/iframe.html.

Inline frames allow you to embed a frame within the document, into which you can load a different page - so in theory, the selection of your state (Eg) from a drop down could call a script to deliver the appropriate towns.