When creating a NuGet PowerShell script, how can you tell the difference between a new install and upgrade?

Question

I have an install.ps1 script in my NuGet package. This script runs both during a new install (after all the files have been copied) and during an upgrade.

I want to show a Getting Started page during a new install, but for an upgrade I want to show the Release Notes.

I found this great answer that tells how to open a URL and it works great. But I am stumped on trying to tell the difference between a new install and an upgrade.

The best solution I have come up with so far is to add a Release Notes link to the top of the Getting Started page, but that is something that could easily be missed by upgraders, and is an unwanted distraction for new installers.

Answer 1

I suppose you could do something with install.ps1 that "dirties" the project in some way on the first install, which you will not clean up with uninstall.ps1. Maybe insert a dummy file into the project (outside of the normal NuGet handling, so the file won't get uninstalled automatically) or add some other dummy element to the project file. Then, when you see those "leftovers" from a previous install (which were purposely not cleanly uninstalled), you will know that you are installing an upgrade.

Answer 2

I don't think it's possible to know if the current operation is install or upgrade. When NuGet upgrades a package, what NuGet does is basically uninstall the existing package and install the new package.