Bagaimana menangani database warisan dalam kerangka kerja Django

Anda dapat menambahkan beberapa metode ke model lama untuk mengambil item terkait sedikit lebih efisien:

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)

Tetapi jika ini bukan terakhir kalinya Anda bekerja dengan data ini mungkin cara yang lebih baik adalah dengan mendefinisikan model Django biasa dengan fks dan menulis sekali skrip untuk mengonversi data lawas ke struktur model baru. Tantangannya tidak boleh lebih dari satu jam.

PERBARUI

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)