CODEWITHSUNDEEP
django
Gabin TEKAM
Gabin TEKAM

Reputation: 83

how can I select items from one table and and sort it by his attribute mark as FK

I want to select items of reservation and sort it by option.effectif where option is declared as FK in table reservation. The sql that I want to have is:

select * from configuration_option, configuration_reservation
where configuration_reservation.option_id= configuration_option.id and valide=True
order by configuration_option.effectif;

For this selection I have tried:

p=Reservation.objects.all().filter(Q(option_id__in=Option.objects.all().order_by('effectif'), valide=True))

The models are:

models

class Reservation( models.Model):
    cours=models.ForeignKey(Cours, on_delete=models.CASCADE)
    enseignant=models.ForeignKey(Enseignant, on_delete=models.CASCADE)
    date_du_jour_reserve=models.DateField("Date du jour reservé")
    option=models.ForeignKey(Option,on_delete=models.CASCADE )
    valide=models.BooleanField(blank=True, default=False)
    class Meta:
        ordering=('date_du_jour_reserve')

class Option(models.Model):
    code_option=models.CharField("Code de l'option", max_length=6,)
    libelle_option= models.CharField("Libélle de l'option", max_length=100)
    effectif=models.IntegerField("Effectif", default=0, validators=[
        MinValueValidator(limit_value=0 , message=" Attention votre option a un effectif négatif"),
    ])

    def __str__(self):
        return self.libelle_option
    class Meta:
        ordering=('libelle_option',)

Upvotes: 1

Views: 30

Answers (1)

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 476659

You should order the queryset itself. You can .order_by(..) [Django-doc] on related models by using double underscores (__):

Reservation.objects.filter(valide=True).order_by('option__effectif')

The filtering here is not necessary on the option, since an Option is a ForeignKey with no null=True, hence that means that each Reservation is always pointing to an Option model.

If you later would allow null=True, you can filter with:

Reservation.objects.filter(
    option__isnull=False,
    valide=True
).order_by('option__effectif')

Upvotes: 1

Related Questions