#25771: Serialization of natural foreign key in migration scripts does not work
----------------------------+----------------------------------------------
Reporter: bowensong | Owner: nobody
Type: Bug | Status: new
Component: | Version: 1.8
Uncategorized |
Severity: Normal | Keywords: database migration serialization
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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The `serializers.serialize(..., use_natural_foreign_keys=True)` is not
working in migration scripts, the `ManyToManyField` always have the value
of the `pk` instead of the `natural_key`
An example to reproduce this bug:
models.py
{{{
# -*- coding: utf-8 -*-
from django.db import models
class Student(models.Model):
student_id = models.CharField(max_length=10, unique=True)
name = models.CharField(max_length=30)
def __unicode__(self):
return self.name
def natural_key(self):
return self.student_id
class Teacher(models.Model):
name = models.CharField(max_length=30)
students = models.ManyToManyField(Student)
def __unicode__(self):
return self.name
}}}
migrations/0002_example.py
{{{
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import migrations, models
from django.core import serializers
def example(apps, schema_editor):
Teacher = apps.get_model("mytest", "Teacher")
json_data = serializers.serialize('json', Teacher.objects.all(),
use_natural_foreign_keys=True)
print json_data
class Migration(migrations.Migration):
dependencies = [
('mytest', '0001_initial'),
]
operations = [
migrations.RunPython(example,
reverse_code=migrations.RunPython.noop)
]
}}}
I applied the initial migration, and inserted some data into those tables.
The dumpdata command output is:
{{{
$ python manage.py dumpdata mytest --natural-foreign
[{"fields": {"student_id": "1234567890", "name": "Alice"}, "model":
"mytest.student", "pk": 1}, {"fields": {"student_id": "9876543210",
"name": "Bob"}, "model": "mytest.student", "pk": 2}, {"fields":
{"students": ["1234567890", "9876543210"], "name": "Petter"}, "model":
"mytest.teacher", "pk": 1}]
}}}
When running the migrate command, output is:
{{{
$ python manage.py migrate mytest 0002
Operations to perform:
Target specific migration: 0002_example, from mytest
Running migrations:
Rendering model states... DONE
Applying mytest.0002_example...[{"fields": {"students": [1, 2], "name":
"Petter"}, "model": "mytest.teacher", "pk": 1}]
OK
}}}
Expected output is:
{{{
$ python manage.py migrate mytest 0002
Operations to perform:
Target specific migration: 0002_example, from mytest
Running migrations:
Rendering model states... DONE
Applying mytest.0002_example...[{"fields": {"students": ["1234567890",
"9876543210"], "name": "Petter"}, "model": "mytest.teacher", "pk": 1}]
OK
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/25771>
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