CODEWITHSUNDEEP
django
HPJM
HPJM

Reputation: 537

Many to many objects duplicated

I am running a process to migrate a lot of call data. I have a model representing a phone line, and another model representing a caller. A phone line can have more than one caller, and a caller can phone more than one phone line. So a many to many relation is needed.

For 442/444 of the phone lines, the code below works and the caller is created and linked to a phone line or added to the relation.

However, in 2 cases duplicates are being created. That is, the phone line will store two caller instances with the same number.

How can I prevent this?

class Caller(models.Model):
    number = models.CharField(max_length=20)
    phoneline = models.ManyToManyField(
        PhoneLine,
        related_name="callers"
    )

class PhoneLine(models.Model):
    number = models.CharField(
        max_length=20, 
        default=""
    )

try:
    caller = Caller.objects.get(number=number)
except ObjectDoesNotExist:
    caller = Caller.objects.create(number=number)
    caller.save()
if not caller.phoneline.filter(pk=phoneline.pk).exists():
    caller.phoneline.add(phoneline)

Upvotes: 0

Views: 55

Answers (1)

user10958847
user10958847

Reputation:

Change your code to

caller, created = Caller.objects.get_or_create(number=number)
caller.phoneline.add(phoneline)

get_or_create method doc.

Django many to many field automatically check duplicate and if exists, not create.

Upvotes: 1

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