Create object if not exists in Django ImportExportModelAdmin - django

Question

I have these two models:
Profile_model.py
class Profile(models.Model):
firstname = models.CharField(max_length=200, blank=False)
lastname = models.CharField(max_length=200, blank=False)
email = models.CharField(max_length=200, unique=True, blank=False)
...
Investment_model.py
class Investment(models.Model):
invested = models.DecimalField(max_digits=9, decimal_places=2, blank=True, null=True)
profile = models.ForeignKey(Profile, on_delete=models.CASCADE)
...
and I have this admin:
Investment_admin.py
class InvestmentResource(resources.ModelResource):
...
firstname = fields.Field(attribute='profile',
widget=ForeignKeyWidget(Profile, field='firstname'),
column_name='firstname')
lastname = fields.Field(attribute='profile',
widget=ForeignKeyWidget(Profile, field='lastname'),
column_name='lastname')
email = fields.Field(attribute='email',
widget=ForeignKeyWidget(Profile, field='email'),
column_name='email')
class Meta:
model = Investment
fields = (
'firstname',
'lastname',
'email',
'invested',)
export_order = fields
class InvestmentAdmin(ImportExportModelAdmin, admin.ModelAdmin):
...
resource_class = InvestmentResource
...
I am using django's ImportExportModelAdmin for bulk imports and exports but when I try to import, I get this error:
I get that its producing this error because the profile hasn't been created yet. But what do I have to do to implement an update_or_create inside the ImportExportModelAdmin?

Answer 1

Option 1 is to use before_import() to scan through the dataset and create Profiles in batch if they do not exist already.
Option 2 is to override methods and create the profiles just before the Investment row is imported. This is only necessary for new Investment objects. This assumes that 'email' will uniquely identify a Profile, you will need to adjust this if not.
Note that firstname and lastname can be set on the Profile object before it is created.
class InvestmentResource(resources.ModelResource):
firstname = fields.Field(attribute='profile__firstname',
widget=CharWidget(), column_name='firstname')
lastname = fields.Field(attribute='profile__lastname',
widget=CharWidget(), column_name='lastname')
email = fields.Field(attribute='email',
widget=ForeignKeyWidget(Profile, field='email'),
column_name='email')
def before_import_row(self, row, row_number=None, **kwargs):
self.email = row["email"]
def after_import_instance(self, instance, new, row_number=None, **kwargs):
"""
Create any missing Profile entries prior to importing rows.
"""
if (
new
and not Profile.objects.filter(
name=self.email
).exists()
):
obj, created = Profile.objects.get_or_create(
name=self.email
)
if created:
logger.debug(f"no Profile in db with name='{self.email}' - created")
instance.profile = obj
Obviously the Profile creation will be a side-effect of an import, so you may need to consider using transactions if you don't want Profiles created if the import fails.