Understanding the IntegrityError with get_or_create()

The IntegrityError: UNIQUE constraint failed you're encountering is likely due to a race condition in your code when using get_or_create(). This method is susceptible to race conditions when multiple processes try to create the same object simultaneously.

The Issue

When you use get_or_create(), Django follows these steps:

1. Try to get an object with the specified lookup parameters
2. If it doesn't exist, create a new one

However, in a concurrent environment (like multiple web requests), two processes might check for existence simultaneously, both find nothing, and both try to create the object - leading to a uniqueness violation.

Solutions

1. Use update_or_create() instead

The update_or_create() method is more robust for this scenario:

PYTHONCopied
for data in objects:
    object, created = self.model1.update_or_create(
        field1=field1,
        field2=field2,
        field3=field3,
        defaults={ 
            'data1': float(data[1]),
            'data2': float(data[2]),
            'data3': float(data[3]),
            'data4': float(data[4]),
            'data5': float(data[5])
        }
    )
    
    if not object.m2mrelation.filter(id=self.id).exists():
        object.m2mrelation.add(self)

2. Use a transaction with savepoint

PYTHONCopied
from django.db import transaction

for data in objects:
    try:
        with transaction.atomic():
            object, created = self.model1.get_or_create(
                field1=field1,
                field2=field2,
                field3=field3,
                defaults={ 
                    'data1': float(data[1]),
                    'data2': float(data[2]),
                    'data3': float(data[3]),
                    'data4': float(data[4]),
                    'data5': float(data[5])
                }
            )
    except IntegrityError:
        # If we get here, another process created the object
        # Get the object that was created
        object = self.model1.get(
            field1=field1,
            field2=field2,
            field3=field3
        )
    
    if not object.m2mrelation.filter(id=self.id).exists():
        object.m2mrelation.add(self)

3. Use UniqueConstraint instead of unique_together

As noted in the Django documentation, unique_together may be deprecated in the future. Consider using UniqueConstraint instead:

PYTHONCopied
class Meta:
    indexes = [
        models.Index(fields=['field1', 'field2', 'field3']),
    ]
    
    constraints = [
        models.UniqueConstraint(
            fields=['field1', 'field2', 'field3'],
            name='unique_model1_fields'
        )
    ]

This won't directly solve your race condition issue, but it's a more modern approach to defining uniqueness constraints in Django.

Additional Note

Make sure that the values for field1, field2, and field3 are consistent across your loop iterations. If these values change within your loop, you might be trying to create objects with different unique combinations.