Judge add or change view in Admin

change Form depending on add or change view

class CourseAdminForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(CourseAdminForm, self).__init__(*args, **kwargs)

        # self.fields['get_learn_time'].label = 'Schulungdauer'
        # self.fields['get_learn_time'].help_text = 'Zeitdauer der gesamten Schulung'
        if self.instance:
            self.fields['image'].required = False