Find Out if an Extension is Installed, part 2

“Hi, this is Library, is Extension 1 home? What about Extension 2, are they home too?”

In my previous post on this topic, I explained how you can use the NAV App Installed App system table to see if a specific extension is installed. I later found out though that the ability to access that table may not always be available in the Dynamics 365 for Financials platform, so back to square one. I want a stable long-lasting solution.

Alas…events!

First…some background on why I need this functionality. I’m developing 2 extensions that share a common library, but I want to develop these extensions so that they are independent, meaning that a customer is able to install only one of the extensions if they choose to, and not be forced to install both. I also need certain features in each extension to act differently depending on if the other extension is installed or not. I know….never simple. 🙂

For those that are not aware, when you submit an extension to AppSource, you are able to submit along with it a library extension. Multiple extensions can be dependent on the same library, which makes it easy to deliver foundation type functions that are shared amongst your extensions. The library extension will not be seen in AppSource, but it will be automatically installed when any of the dependent extensions are installed.

What this also means is that when I am developing in the context of one of my “functional” extensions, I am able to directly reference objects that are contained in my library because the library is guaranteed to exist when the functional extension is installed. What I cannot do though is the opposite, because although the library extension knows that at least one functional extension was installed, it does not know directly which one it was. Make sense!? Clear as mud I know. 🙂

In the example below, let’s assume that I have a “Library” extension, and two functional extensions, brilliantly named “Extension 1” and “Extension 2”.

First, I need to create a codeunit in my library extension that will act as the “extension handler” so to speak. In other words it will house the functions required to determine what extensions are installed. In my library codeunit, I’ll add the following functions:

CheckIsExtensionInstalled(ExtensionAppID : GUID) : Boolean
IsInstalled := FALSE;
IsExtensionInstalled(ExtensionAppID,IsInstalled);
EXIT(IsInstalled);

GetExtension1AppID() : GUID
EXIT('743ba26c-1f75-4a2b-9973-a0b77d2c77d3');

GetExtension2AppID() : GUID
EXIT('a618dfa7-3cec-463c-83f7-7d8f6f6d699b');

LOCAL [IntegrationEvent] IsExtensionInstalled(ExtensionAppID : GUID;VAR IsInstalled : Boolean)

The above functions allow me to call into the codeunit to determine if either of my functional extensions are installed. The GUIDs that I used are samples above, but you should use the same GUID that is used in the corresponding extension manifest file.

The piece that makes this all possible is the published event IsExtensionInstalled. What I can do now is from within each functional extension, I can subscribe to that event so that each extension can basically give “answer” the library when it asks if it’s installed.

To do that, I create 2 more codeunits, one in each functional extension. These codeunits will contain a subscriber to the event that we published in the library codeunit. This way, if the extension is installed, its subscriber will respond to the event and let the library know that it is installed. If the extension is not installed then there won’t be anyone home to answer that call.

Extension 1

LOCAL [EventSubscriber] OnCheckIsExtensionInstalled(ExtensionAppID : GUID;VAR IsInstalled : Boolean)
IF ExtensionAppID = ExtensionHandler.GetExtension1AppID THEN
  IsInstalled := TRUE;

Extension 2

LOCAL [EventSubscriber] OnCheckIsExtensionInstalled(ExtensionAppID : GUID;VAR IsInstalled : Boolean)
IF ExtensionAppID = ExtensionHandler.GetExtension2AppID THEN
  IsInstalled := TRUE;

So how do we use all of this? Easy, of course. The example below shows code that you could use from either of the functional extensions, so that your extensions can act differently depending on what other extensions are installed.

IF LibraryCodeunit.CheckIsExtensionInstalled(LibraryCodeunit.GetExtension1AppID) THEN
  MESSAGE('Extension 1 is installed.');

IF LibraryCodeunit.CheckIsExtensionInstalled(LibraryCodeunit.GetExtension2AppID) THEN
  MESSAGE('Extension 2 is installed.');

There, easy right? If you want to try it out yourself, you can grab the above example on GitHub here.

Now, while you can do this if you own all of the source code for each extension, you cannot use this solution to determine if “any old random extension” is installed, as you need to add the subscriber function to the functional extension code. But, if you are developing out multiple extensions and if you need to know which of them are installed, then this solution will work wonderfully!

Happy coding!

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One thought on “Find Out if an Extension is Installed, part 2

  1. Pingback: Find Out if an Extension is Installed | NAV Bits and Bytes

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