Fix Add-PnPDataRowsToSiteTemplate setting KeyColumn to null

[jackpoz]

Type

• Bug Fix
• New Feature
• Sample

Related Issues?

Fixes pnp/pnpframework#1020

What is in this Pull Request ?

This PR fixes Add-PnPDataRowsToSiteTemplate setting KeyColumn to null when the -KeyColumn parameter is not passed. It also fixes the case of -KeyColumn parameter value being ignored.
The old code was updating listInstance.DataRows.KeyColumn only when the -KeyColumn parameter was null, but it should update it only when it's not null.

How to reproduce steps:

1. Get a list template

Get-PnPSiteTemplate -ListsToExtract "Test simple list" -Handlers Lists -Out "list.xml"

2. Manually add a DataRows section to the ListInstance with KeyColumn value set

<pnp:DataRows UpdateBehavior="Overwrite" KeyColumn="Title">
</pnp:DataRows>

3. Call Add-PnPDataRowsToSiteTemplate without -KeyColumn parameter

Add-PnPDataRowsToSiteTemplate -List "Test simple list" -Path "list.xml"

4. Check the KeyColumn attribute in the template

[gautamdsheth]

Awesome stuff as always @jackpoz , thank you !