संबंधित वस्तुओं को थोड़ा अधिक कुशलता से पुनः प्राप्त करने के लिए आप लीगेसी मॉडल में कुछ तरीके जोड़ सकते हैं:
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)
लेकिन अगर यह आखिरी बार नहीं है जब आप इस डेटा के साथ काम करते हैं तो शायद बेहतर तरीका है कि नियमित django मॉडल को fks के साथ परिभाषित करें और विरासत डेटा को एक नई मॉडल संरचना में बदलने के लिए एक बार एक स्क्रिप्ट लिखें। चुनौती में एक घंटे से अधिक समय नहीं लगना चाहिए।
अपडेट करें
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)
