How to detect every single part in-game?

I basically want to make cast shadow of every single part in-game false with the command bar. Issue is there are parts in models, and there are many models in even more models.

I do know the basics and I'm aware that this won't work:

for i,v in pairs(game.Workspace:GetChildren()) do 
if v.className == "Part" then 
v.CastShadow = false
end 
end 

Any way to execute this with the command bar?