Go through the user input, get/validate some important values.

def parse_input(self):
        """
        Go through the user input, get/validate some important values.
        """
        app_split = self.args[0].split('.')
        app = app_split[0]
        model_name = app_split[1].lower()
        
        self.model = get_model(app, model_name)

        # String field name to re-generate.
        self.field = self.args[1]