Array of foreign keys in Django Model

Question

I'm not sure this is the best title, but I'm having trouble phrasing it simply. Basically, I'm creating a model that represents a business. This includes and address, operating hours, etc. It's the operating hours that are tripping me up. I have my address

class Address(models.Model):
    --snip--
   Business = models.ForeignKey(BusinessInfo)

So each business has one or more location addresses. I'm looking to do similar with Hours

class HoursOnDay(models.Model):
    open = isOpen = models.BooleanField()
    open = models.TimeField(null=True)
    closed = models.TimeField(null=True)

What I want to enforce is that each business has to have an array of 7 HoursOnDay - one for each day of the week. I can't seem to stumble on the obvious, elegant way to do this. Is there a good way to model this in django?

Answer 1

use ManyToManyField:

class HoursOnDay(models.Model):
    is_open = models.BooleanField()
    open = models.TimeField(null=True)
    closed = models.TimeField(null=True)

class Day(models.Model):
    hours = models.ManyToManyField(HoursOnDay)

class Business(models.Model):
    days = models.ManyToManyField(Day)

if you want to have limit for 7hours and 7days you can check Limit number of model instances to be created

Answer 2

I have come across a similar problem (needed a bunch of fields for every hour of the day) and reached the following conclusion:

The most djangoish way to do this, is to not try and do anything smart. If you need a bunch of fields seven times, just copy paste the fields and give them different postfix or prefix. Eg:

class Business(models.Model):
    --snip--
    monday_is_open = models.BooleanField()
    monday_opens_at = models.TimeField(null=True)
    monday_closes_at = models.TimeField(null=True)

    tuesday_is_open = models.BooleanField()
    tuesday_opens_at = models.TimeField(null=True)
    tuesday_closes_at = models.TimeField(null=True)

    wednesday_is_open = models.BooleanField()
    wednesday_opens_at = models.TimeField(null=True)
    wednesday_closes_at = models.TimeField(null=True)

    ...

    sunday_is_open = models.BooleanField()
    sunday_opens_at = models.TimeField(null=True)
    sunday_closes_at = models.TimeField(null=True)

Of course Americans (and others?) would start with sunday, but you get the idea.

Following this approach greatly simplifies updating opening hours. This approach (and what you requested) fail to model changing opening hours from week to week, but that is probably not your need either.

Also, if you are concerned with schema normalization, get rid of the is_open, and just use xxx_opens_at__isnull=True, xxx_closes_at__isnull=True where you would have used xxx_is_open=True .

You can still do smart stuff with iteration across the weekdays in Business.clean() .