Django: Is there any way to have "unique for date range"?

Question

If my model for Items is:

class Item(models.Model):
    name = models.CharField(max_length=500)
    startDate = models.DateField("Start Date", unique="true")
    endDate = models.DateField("End Date")      

Each Item needs to have a unique date range. for example, if i create an Item that has a date range of June 1st to June 8th, how can I keep and Item with a date range of June 3rd to June 5th from being created (or render an error with template logic)?

PLEASE let me know if I can clarify this question better!

Answer 1

http://docs.djangoproject.com/en/dev/ref/models/fields/#unique-for-date

Answer 2

You can not enforce this on the model level, you can however override the save method to something like this:

class Item(models.Model):
    name = models.CharField(max_length=500)
    startDate = models.DateField("Start Date", unique="true")
    endDate = models.DateField("End Date")     

    def save(self, *args, **kwargs):
        try:
            Item.objects.get(Q(startDate__range=(self.startDate,self.endDate))|Q(endDate__range=(self.sartDate,self.endDate))|Q(startDate__lt=self.startDate,endDate__gt=self.endDate))
            #raise some save error
        except Item.DoesNotExist:
            super(Item,self).save(*args,**kwargs)

edit: maybe the date range check can go easier, long time since I did it, but it shows the general concept :).