[Python] How to migrate Enumfield values in Django properly?

Suppose we have an Enum:

class MyEnum(Enum):
FOO = "FOO"
BAR = "BAR"
BAZ = "BAZ"


that is used in a field:

from enumfields import EnumField

class FooModel (models.Model)
foo_field = EnumField(
MyEnum, null=True, blank=True, default=MyEnum.FOO)


Then I want to remove one of the fields in MyEnum, because I do not want value FOO in my database anymore

class MyEnum(Enum):
BAR = "BAR"
BAZ = "BAZ"


from enumfields import EnumField

class FooModel (models.Model)
foo_field = EnumField(
MyEnum, null=True, blank=True, default=MyEnum.BAR)


I need to migrate data, so my migration may look like this:

def migrate_not_for_sale_to_private(apps, schema_editor):
FooModel = apps.get_model("foo", "FooModel")
for obj in FooModel.objects.all():
if obj.foo_field == "FOO":
obj.foo_field = "BAR"
obj.save()


This one fails, because I changed allowed values for foo_field to BAR and BAZ, and so if obj has value FOO, it blows up with not allowed value error.

How one should do it properly? I could leave MyEnum values as they are, marking one as legacy, but in a long run it leads to a lot of potential legacy fields. The other way could be running raw SQL command (assume I am using PostgreSQL).

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