How to setup group combo php

Im very new to dhtml and basically all programing languages.

Im trying to create a grouped combo boxes and i found the below example; however, i dont know how to set up the php file that is being loaded.
Can someone please advise on how the php file needs to be setup for the combo box. share links if any.

There is no specific data format for the grouping extension of the dhtmlxCombo.
You need to generate a common json/xml file: … serverside
Here you can find a working example of the grouping combos: … ombos.html

Okay I understand now what you mean about the extension file.

I was able to get one combo box working using an xml file to load the information.
Now i want to try and get grouping combos source code working using xml.

Im having trouble understand how to use the +value in the code and how to set up the second xml file.
Would i need to set up two xml files , one for each combo box?


You can’t use a static xml file for the second combo.

The main idea, that you are loading a static data in the master combo, and each time when it changes, data for second combo is reloaded. To work, such approach need to have a dynamic data script as source for the second combo, which will generate a different data each time, based on values selected in the master combo.