from django.db import models class Experiment(models.Model): start_datetime = models.DateTimeField() start_date = models.DateField(null=True, blank=True) start_time = models.TimeField(null=True, blank=True) end_datetime = models.DateTimeField(null=True, blank=True) end_date = models.DateField(null=True, blank=True) end_time = models.TimeField(null=True, blank=True)