Check-in document via powershell

Your best strategy would be to use the REST API from PowerShell if you want to do everything in PowerShell script: logging on to a vault,  creating an object, settings properties and uploading a file.

I have been trying to use the M-Files COM API from PowerShell (Windows PowerShell 5.1), and API calls. Logging in into a vault and using methods like $vault.ObjectFileOperations.FindFilesByChecksumWithNumericalDigests(...) can be easily done in PowerShell script, but setting up some COM objects that need to be used in other API methods is a PITA and I haven't found any way to do it in PowerShell (for example setting up search conditions). PowerShell will throw an error like  "Cannot convert the "System.__ComObject" ... to "Object" which has to do how PowerShell lazy binds COM objects.

Should you really need to use the M-Files COM API, then program the functionality in a c# .NET full framework 4.x DLL and call this from PowerShell. You can easily add DLLs into the PowerShell runtime with Add-Type cmdlet and use the DLL classes from PowerShell.

Thanks - I guess I will write a small EXE to encapsulate this and simply call it from PowrrShell.

That is a possibility as well, but you would need some plumbing to start the exit, wait for it to exit, handle exit code, output and error channel. 

Consider encapsulating the functionality into a .NET DLL instead of an EXE and injecting it into the PowerShell runtime/.NET Appdomain using "Add-Type", like this:

• https://activedirectoryfaq.com/2016/01/use-net-code-c-and-dlls-in-powershell/
• https://devblogs.microsoft.com/scripting/use-powershell-to-work-with-the-net-framework-classes/