Hierachical dropdown lists

[Anon]

This may be tough to explain but I've got to try - it's killing me...

I have 3 dropdown lists that are generated from a MySQL database. Each one decides the content of the next (i.e. The selection in LIST1 decides LIST2 which in turn decides LIST3). I've already cracked the client side Javascript to switch the dropdown lists depending on users input using a very small amount of test data. Are you still with me so far?

My problem is that there is just too much data to write it all out into a single page. LIST1 might be 30-40 and each of these might have have 10-20 entries in LIST2. And each of those may have 10-20 entries in LIST3. This leads to 40 x 20 x 20 which is 16000 permutations and that is just too much! Still making sense?

So my question is this:

Given that I can only sensibly expect to populate LIST1 when the page loads, how can I achieve the result I am looking for? I.E. Populate LIST2 once a selection is made in LIST1 and then repeat this for LIST3 when an entry in LIST2 is selected

IDEA 1 - I could simply reload the form once a selection is made in LIST1 but then I would have to pull across the input already made into other fields. Plus I would have to repeat the exercise when a selection is made in LIST2 to set up LIST3. Too many delays I'm guessing.

IDEA 2 - I could use a frame for each dropdown but unfortunately the layout has dictated that I cannot do this. Plus I'm not keen on frames anyway.

Thanks in advance
Richard

[Anon]

Hi,

You could make it in 3 steps.

1. The user selects from the LIST1 presses a button NEXT. The selected item is send to the next page.

2. The selected Items is written as simple HTML text and the LIST2 of the second page is populated with help of the variable selected in LIST1

3. Same as step2

making sense?

You can set on all page a back button so the user can always get back to select other items.

This is just an IDEA --> a little bit like Wizards do in software's.

Hope this is useful

[Anon]

There is a tutorial at www.zend.com that is similiar to your problem. Try this link
http://www.zend.com/zend/tut/drop-down.php

However with the amount of data that you need to represent, it might be better to break it up into multiple steps(wizard like) like suggested earlier.

[Anon]

Nice idea but I should have made it clear that ideally I need to keep this all on one screen or the same screen but refreshing parts of it from the server). The end user should only be presented with one input form need to

I like the "wizard" idea but it doesn't make sense in this situation to have a whole screen for each dropdown list.

I think I'll try a brain flash I've just had...More on this if it works...

Thanks for all the ideas