A Beginners' Guide to Blazor WebAssembly - Add, edit & delete child records

How to add a toolbar to a data grid and then add, edit and delete child records, linking them to a parent record selected from a drop-down list. We will also warn the user if they forget to select a parent record before adding a child, and if they also forget to select a child record when attempting to edit or delete one.
Useful links:
Video script & code: blazorcode.uk/countriesandcit...

[@lantisdylan]

Do you use mudblazor?

[@christopherbell7186]

No. I use Syncfusion controls, but I'm sure MudBlazor is equally good.

[@broadshare]

Mudblazor is good