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2016-04-06T20:15:45Z

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I'd say this is one of the more confusing aspects of callbacks.

Some people reference this mysterious directory as ...rt3/local/html/Callbacks/<[[MyCallbacks]]>/...

Others reference it even MORE mysteriously as ...rt3/local/html/Callbacks/*/...

Do this -- don't make yourself crazy. Wherever it says anything like that -- just name the directory

[[MyCallbacks]]

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Now, since you're here. I'm guessing you're slightly baffled about all this Callback gibberish anyway.

Here's what they're saying.

In RT, each page is made up of a lot of different parts. Each of these parts is stored in a different area in the (hard to navigate) rt3 source tree.

Now, in each page, there are sub-objects -- often referred to as Elements -- potentially referred to as other things as well. These Elements in the original source tree hold the magical Callbacks (don't panic, I'm still explaining).

So! For example -- you open a Ticket. It shows you all that Metadata junk (that's a group of Elements), and it shows you the History (that's an Element) and so on.

Let's pretend that you want to mess with the History display (as I did when I wanted to learn this painful lesson).

First you have to find the original bit that makes this happen. You'll find it under the .../share/html/Ticket tree.

That means that it's a sub-Element of the Ticket display... that almost makes sense.

Under the .../share/html/Ticket directory -- there's an Elements directory.

Inside THAT directory is a little piece of code called "[[ShowHistory]]".

Now -- as a hardcore coder, you COULD edit that file -- but you'd be sorry later on. RT changes dramatically between versions, and you might make a lot of changes to that Element and then have that work lost later on.

The right way to edit it directly is to create an "override" version under .../local/html/Ticket/Elements/[[ShowHistory]] ... but even THAT might not be great because the code would still be subject to change without notice.

So you use Callbacks! Let's get excited.

All a Callback does is check a directory for potential extra code.

So, in this "[[ShowHistory]]" Element, there's are many Callbacks -- one is called "[[SkipTransaction]]"

What that means is that when the [[ShowHistory]] Element's code is being run, it checks against the .../local/html/Callbacks/[[MyCallbacks]]/Ticket/Elements/[[ShowHistory]] directory to see if there is a FILE in there named "[[SkipTransaction]]" ... if so, run the code in that file.

That's the magic -- it's a way of calling out to new code without losing your place in the source code.

SOOOO!!!!

When you want to edit a Callback, you create a FILE according to the name suggested by the programmer who made that Callback -- and store it in the right place as described above.

Hope that helps.

[[MGMead]]

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