I imagine Radarr always has IMDB IDs, but for Sonarr that's not always the case, it'd be more reliable to have TheTVDB links instead.

I imagine Radarr always has IMDB IDs, but for Sonarr that's not always the case, it'd be more reliable to have TheTVDB links instead.
Every TV series on my sonarr has IMDB link... The links from IMDB also has nice preview... So i prefer IMDB.

Trakt also is good:

Making it optional and giving a choice should be easy enough whenever someone picks this up.

I recently thought about this too.
I guess the easy way would be adding the imdb url in the GetMessage method in NotificationService.cs just like Radarr does. But maybe you have something else in mind? @markus101

I can do this, it does't seem to be really hard, but I'm a bit confused as how would I make it an optional feture. It seems that it could either be an option for the telegram connection, or it could be included in the GetMessage method, but that would make it appear on all connections, and I don't see how could I make that optional.

I don't think we want to add it to every message by adding to to NotificationService.

The simplest solution would be to add an option to TelegramSettings, then conditionally append it to the message before sending, which can be done with a function in Telegram.cs that takes the message input and outputs the updated message.

I'd be happy to take a shot at this if nobody else has given it a go. I've already put together a reference implementation that includes an IMDb link. However, I'm a bit uncertain about how to generate a TVDb URL from the ID. It would be great to have a conditional setting that allows you to pick the database you prefer, although we should be careful not to make it overly complex. If IMDb suits your needs, that would be the most straightforward option.

I'm a bit uncertain about how to generate a TVDb URL from the ID

Series details uses the IDs to create links to the various metadata sites so you can see how it's done there.

It would be great to have a conditional setting that allows you to pick the database you prefer, although we should be careful not to make it overly complex

There are quite a few examples where an enum is used to generate a select list on the UI (ReleaseTypeSpecification for Custom Formats is a recently added example).