Question

I have written a function in Django to look up an object based on its type that works akin to the following:

def lookup(modelType, item_id):
    try:
        return eval(modelType).objects.get(pk=item_id)
    except ObjectDoesNotExist:
        return None

lookup(Course, 14) should return Course.objects.get(pk=14) if there is a Course object with ID 14.

Is this function feasible to write? Thank you.

Answer 1

If you want to use lookup(Course, 14) then do this.

def lookup( the_model, item_id ):
    try:
        the_model.objects.get( pk=item_id )
    except the_model.DoesNotExist:
        return None

If you want to keep using the function you wrote, then you have to pass the model as a string.

lookup( "Course", 14)

Also. return None is a very bad idea. It’s usually much better to use exceptions properly.