date_creation = models.DateTimeField(auto_now_add=True)
date_modification = models.DateTimeField(auto_now=True)
date_debut = models.DateField(verbose_name="Date de début",
- help_text=HELP_TEXT_DATE)
+ help_text=HELP_TEXT_DATE,
+ null=True, blank=True)
date_fin = models.DateField(null=True, blank=True,
verbose_name="Date de fin",
help_text=HELP_TEXT_DATE)