Django models

We can now take a look at how these normalized tables can be represented as Django models. Composite keys are not directly supported in Django. The solution used here is to apply the surrogate keys and specify the unique_together property in the Meta class:

class Origin(models.Model): 
    superhero = models.ForeignKey( 
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE) 
    origin = models.CharField(max_length=100) 
 
    def __str__(self): 
        return "{}'s orgin: {}".format(self.superhero, self.origin) 
 
 
class Location(models.Model): 
    latitude = models.FloatField() 
    longitude = models.FloatField() 
    country = models.CharField(max_length=100) 
 
    def __str__(self): 
        return "{}: ({}, {})".format(self.country, 
                                     self.latitude, self.longitude) 
 
    class Meta: 
        unique_together = ("latitude", "longitude") 
 
 
class Sighting(models.Model): 
    superhero = models.ForeignKey( 
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE) 
    power = models.CharField(max_length=100) 
    location = models.ForeignKey(Location, on_delete=models.CASCADE) 
    sighted_on = models.DateTimeField() 
 
    def __str__(self): 
        return "{}'s power {} sighted at: {} on {}".format( 
            self.superhero, 
            self.power, 
            self.location.country, 
            self.sighted_on) 
 
    class Meta: 
        unique_together = ("superhero", "power")