I have a module setup that uses ajax calls, should I have one file for all my ajax calls or should all the calls have their own file?
Example of what I mean:
index.php ------ With the ajax calls
Should I have one file such as 'ajax.php' that has functions for update, delete, and edit. Or should I have update.php, delete.php, and edit.php?
Depends on how you want to structure it. If you are looking to do page based permissions at any point, having multiple files may be beneficial. However, having all the actions in a single file will make your life a little easier when reading through the code.
You need to pick what is best for your design.
All these actions are db action, so i would just group them in one file. Unless your deleting, updating and editing is tedious, i would give one script the ability to perform all. Otherwise having a one file per action performed seems like going overboard. Generally speaking, you should write your scripts to by dynamic and reusable.
It'll be definitely more convenient for you to have just one entrance point to your program. Put all your operations in one file (like, in index.php) and use switch or whatever logic you want to fire appropriate action. Moreover, even if your have enough logic to separate in to different files or modules, one entrance point still will be nice design decision so you can, for example, perform consistent access control, logging, etc.
It all depends on the functions your application will need to complete.
If you will have several functions that edit, several functions that delete, and several functions that update, all functions having separate needs and requirements (thus cannot be made into a single universal function), then separate files for each function (edit_ajax.php, update_ajax.php, etcetera) would be easiest in the long run.
Or, are these Ajax calls only a few of the ones you'll need involving Ajax? In that case, it may be better to group them by their domain function, which is what they're handling (students_ajax.php if those Ajax calls involve updating, deleting and editing students, for example).
Also, make sure your function calls are separated by concern if your application architecture supports it. If these calls are purely sending data to PHP to update your database, keep them in a separate file from the Ajax calls that are merely passing parameters in for a specific set of HTML to load into a page.
Ultimately, your choice is heavily dependent on your application architecture and design style, which may sound more obvious than needed but very true nonetheless.
I usually use multiple files with one include file that they all use to get all their functions.
That way you get the convenience of a single library, but it's much cleaner and more straightforward having a different file for each.
I would suggest using folders to separate your different pages though. Otherwise your ajax folder gets all cluttered and that can be worse than your code file being cluttered.