I am having trouble loading Django fixtures into my MySQL database because of contenttypes conflicts. First I tried dumping the data from only my app like this:
./manage.py dumpdata escola > fixture.json
but I kept getting missing foreign key problems, because my app "escola" uses tables from other applications. I kept adding additional apps until I got to this:
./manage.py dumpdata contenttypes auth escola > fixture.json
Now the problem is the following constraint violation when I try to load the data as a test fixture:
IntegrityError: (1062, "Duplicate entry 'escola-t23aluno' for key 2")
It seems the problem is that Django is trying to dynamically recreate contenttypes with different primary key values that conflict with the primary key values from the fixture. This appears to be the same as bug documented here: http://code.djangoproject.com/ticket/7052
The problem is that the recommended workaround is to dump the contenttypes app which I'm already doing!? What gives? If it makes any difference I do have some custom model permissions as documented here: http://docs.djangoproject.com/en/dev/ref/models/options/#permissions
manage.py dumpdata --natural
will use a more durable representation of foreign keys. In django they are called "natural keys". For example:
Permission.codename is used in favour of Permission.id
User.username is used in favour of User.id
Read more: natural keys section in "serializing django objects"
Some other useful arguments for dumpdata
:
--indent=4 make it human readable.
-e sessions exclude session data
-e admin exclude history of admin actions on admin site
-e contenttypes -e auth.Permission exclude objects which are recreated automatically from schema every time during syncdb. Only use it together with --natural or else you might end up with badly aligned id numbers.
The answers here all old... As of 2017, the best answer is:
manage.py dumpdata --natural-foreign --natural-primary -e contenttypes -e auth.Permission --indent 4
Yes, this is really irritating. For a while I worked around it by doing a "manage.py reset" on the contenttypes app prior to loading the fixture (to get rid of the automatically-generated contenttypes data that differed from the dumped version). That worked, but eventually I got sick of the hassles and abandoned fixtures entirely in favor of straight SQL dumps (of course, then you lose DB portability).
update - the best answer is to use the --natural
flag to dumpdata
, as noted in an answer below. That flag did not exist yet when I wrote this answer.
Try skipping contenttypes when creating fixture:
./manage.py dumpdata --exclude contenttypes > fixture.json
It worked for me in a similar situation for unit tests, your insight regarding the contenttypes really helped!
I was not using MySQL but instead importing some data from a live server into sqlite. Clearing the contenttypes
app data before performing loaddata
did the trick:
from django.contrib.contenttypes.models import ContentType
ContentType.objects.all().delete()
quit()
And then
python manage.py loaddata data.json
I have resolved this issue in my test cases by resetting the contenttypes app from the unit test prior to loading my dump file. Carl suggested this already using the manage.py
command and I do the same thing only using the call_command
method:
>>> from django.core import management
>>> management.call_command("flush", verbosity=0, interactive=False)
>>> management.call_command("reset", "contenttypes", verbosity=0, interactive=False)
>>> management.call_command("loaddata", "full_test_data.json", verbosity=0)
My full_test_data.json
fixture contains the contenttypes app dump that corresponds to the rest of the test data. By resetting the app before loading, it prevents the duplicate key IntegrityError
.
You need to use natural keys to represent any foreign key and many-to-many relationships. Moreover, it might be a good idea to exclude the session
table in the sessions
app, and the logentry
table in the admin
app.
Django 1.7+
python manage.py dumpdata --natural-foreign --exclude contenttypes --exclude auth.permission --exclude admin.logentry --exclude sessions.session --indent 4 > fixture.json
Django <1.7
python manage.py dumpdata --natural --exclude contenttypes --exclude auth.permission --exclude admin.logentry --exclude sessions.session --indent 4 > fixture.json
According to the Django documentation, --natural
has been deprecated in version 1.7, so the option --natural-foreign
should be used instead.
You can also omit the primary key in the serialized data of this object since it can be calculated during deserialization by passing the --natural-primary
flag.
python manage.py dumpdata --natural-foreign --natural-primary --exclude contenttypes --exclude auth.permission --exclude admin.logentry --exclude sessions.session --indent 4 > fixture.json
python manage.py dumpdata --natural-primary --exclude=contenttypes --exclude=auth.Permission --exclude=admin.logentry --exclude=sessions.session --indent 4 > initial_data.json
This works for me. Here I am excluding everything bubt the actual models.
If you see any other model other than the models that you created you can safely exclude those. One drawback of this approach is you loose on log data as well as auth data.
./manage.py dumpdata app.Model --natural-foreign
will change
"content_type": 123
to
"content_type": [
"app_label",
"model"
],
And fixture works for TestCase
now
It's really, really annoying .. I get bitten by this every single time.
I tried to dumpdata with --exclude contenttypes and --natural, I always get problems..
What works best for me is simply doing a truncate table django_content_type;
after the syncdb and THEN load the data.
Of course for initial_data.json autoloading you're fallball.
Django 2.2.5
python manage.py dumpdata --exclude=contenttypes > datadump.json
it helped me
I'm going to give another possible answer that I just figured out. Maybe it'll help the OP, maybe it'll help somebody else.
I've got a many-to-many relationship table. It has a primary key and the two foreign keys to the other tables. I found that if I have an entry in the fixture whose two foreign keys are the same as another entry already in the table with a different pk, it will fail. M2M relationship tables have a "unique together" for the two foreign keys.
So, if it's a M2M relationship that is breaking, look at the foreign keys it's adding, look at your database to see if that pair of FKs are already listed under a different PK.
I had encountered similar error sometimes ago. It turned out that I was trying to load the fixtures before creating the necessary tables. So I did:
$ python manage.py makemigrations
$ python manage.py migrate
$ python manage.py loaddata fixtures/initial_data.json
And it worked like a charm
I tried every method from above, Nothing worked for me. I have to exclude the complete auth model and works fine.
python manage.py dumpdata --natural-primary --exclude=contenttypes --exclude=auth --exclude=admin.logentry --exclude=sessions.session --indent 4 > live.json
In my case I had dumped the data from auth
(./manage.py dumpddata auth > fixtures/auth.json
) to use the fixture for testing purposes.
The development continued and I removed most of the models I had defined in models.py
and this is when I started to see this annoying problem.
My solution was regenerating the auth.json fixture again. This one had removed lots of entries in auth.permission
related to the old models I had.
I've fixed this by adding in my tests setUp and tearDown
from django.core import management
=====
def setUp(self):
management.call_command("loaddata", "all-data.yaml", verbosity=0)
super(login_page_test, self).setUp()
def tearDown(self):
management.call_command("flush", verbosity=0, interactive=False)
super(login_page_test, self).setUp()
Success story sharing
-e contenttypes -e auth.permission
with--natural
? I just tried without the--natural
option and it worked. Also the documentation here says one should use this option if DUMPINGauth.permission
andcontenttypes
.ContentType
andPermission
are not guaranteed to get same id as they had before. Your data dump contains ids which might reference different objects on anather database where you will loaddata. It might worked for you because of one of these reasons: 1) your data didn't had any reference to these objects 2) original ids of Permission/ContentTypes were preserved 3) your loaddata was succesful but you actually have corrupt data due to objects referring to wrong objects and you don't yet know about it--natural
is now deprecated in favor of--natural-foreign
(and--natural-primary
)manage.py dumpdata --natural-foreign --natural-primary -e contenttypes -e auth.Permission --indent 4 > project_dump.json
--natural
has now been completely removed, not just deprecated. Use--natural-foreign
or--natural-primary
instead.