Sie können älteren Modellen einige Methoden hinzufügen, um verwandte Elemente etwas effizienter abzurufen:
class Listflower(models.Model):
especies_id = models.AutoField(primary_key=True)
family_id = models.IntegerField(blank=True, null=True)
especies = models.CharField(max_length=255, blank=True, null=True)
class Meta:
managed = False
db_table = 'listflower'
def get_family(self):
return FamilyModel.objects.get(family_id=self.family_id)
class Estate(models.Model):
estate_id = models.AutoField(primary_key=True)
estate_name = models.CharField(max_length=100, blank=True, null=True)
class Meta:
managed = False
db_table = 'estates'
def get_flowers(self):
flower_ids = Flower2Estate.objects.filter(estate_id=self.estate_id).values_list('especies_id', flat=True)
return Listflower.objects.filter(especies_id__in=flower_ids)
Aber wenn es nicht das letzte Mal ist, dass Sie mit diesen Daten arbeiten, ist es wahrscheinlich besser, reguläre Django-Modelle mit fks zu definieren und einmal ein Skript zu schreiben, um ältere Daten in eine neue Modellstruktur zu konvertieren. Die Herausforderung sollte nicht länger als eine Stunde dauern.
AKTUALISIEREN
class FlowerFamily(models.Model):
# assuming you old family model has
# "family_id" and "family_name" fields
family_id = models.IntegerField(blank=True, null=True)
family_name = models.CharField(max_length=255, blank=True, null=True)
class Flower(models.Model):
# you might want preserve old model fields in the new model
# at least id fields
especies_id = models.IntegerField(blank=True, null=True)
family_id = models.IntegerField(blank=True, null=True)
especies = models.CharField(max_length=255, blank=True, null=True)
family = models.ForegnKey(FlowerFamily, related_name='flowers')
class NewEstate(models.Model):
estate_id = models.IntegerField(blank=True, null=True)
estate_name = models.CharField(max_length=100, blank=True, null=True)
flowers = models.ManyToManyField(Flower, related_name='estates')
# this is a slightly primitive example
# in real life you might want to use get_or_create instead of direct creation
# in case script fails and you'll need to run it again
# also objects.get() might better be used with try-except ObjectDoesNotExist
def convert_legacy():
# create new instances
for ff in YourOldFamilyModel.objects.all():
new_ff = FlowerFamily(family_id=ff.family_id, family_name=ff.family_name)
new_ff.save()
for fl in Listflower.objects.all():
new_fl = Flower(...)
family = FlowerFamily.objects.get(family_id=fl.family_id)
new_fl.family = family
new_fl.save()
# same thing for Estate
for ...:
new_estate ...
new_estate.save()
# and restore relations
flower_ids = Flower2Estate.objects.filter(estate_id=new_estate.estate_id).values_list('especies_id', flat=True)
for new_lf in Flower.objects.filter(especies_id__in=flower_ids):
new_estate.flowers.add(new_fl)
