How do I return to a function and pass it parameters in the url?

Hi EEers,

I am currently doing this after running an update function:

return $this->view_gradebook($LANG->line('assignment_added'));

Which results in the following url:

index.php?S=0&C=modules&M=gradebook

What I need to do is return to the following url:

index.php?S=0&C=modules&M=gradebook&P=view_gradebook&class_id=1&class_group=9

Does anyone know how I can return the longer url with parameters?

Thanks, Zac