Django - makemigrations - No changes detected

Question

I was trying to create migrations within an existing app using the makemigrations command but it outputs \"No changes detected\".

Usually I create new apps using the

Answer 1

I had copied a table in from outside of django and the Meta class defaulted to "managed = false". For example:

class Rssemailsubscription(models.Model):
    id = models.CharField(primary_key=True, max_length=36)
    ...
    area = models.FloatField('Area (Sq. KM)', null=True)

    class Meta:
        managed = False
        db_table = 'RSSEmailSubscription'

By changing manged to True, makemigrations started picking up changes.

Answer 2

It is a comment but should probably be an answer.

Make sure that your app name is in settings.py INSTALLED_APPS otherwise no matter what you do it will not run the migrations.

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',

    'blog',
]

Then run:

./manage.py makemigrations blog

Answer 3

The possible reason could be deletion of the existing db file and migrations folder you can use python manage.py makemigrations <app_name> this should work. I once faced a similar problem.

Answer 4

Another possible reason is if you had some models defined in another file (not in a package) and haven't referenced that anywhere else.

For me, simply adding from .graph_model import * to admin.py (where graph_model.py was the new file) fixed the problem.

Answer 5

I had another problem not described here, which drove me nuts.

class MyModel(models.Model):
    name = models.CharField(max_length=64, null=True)  # works
    language_code = models.CharField(max_length=2, default='en')  # works
    is_dumb = models.BooleanField(default=False),  # doesn't work

I had a trailing ',' in one line perhaps from copy&paste. The line with is_dumb doesn't created a model migration with './manage.py makemigrations' but also didn't throw an error. After removing the ',' it worked as expected.

So be careful when you do copy&paste :-)

Answer 6

In my case, I first added a field to the model, and Django said there're no changes.

Than I decided to change the "table name" of the model, makemigrations worked. Than I changed table name back to default, and the new field was also there.

There is a "bug" in django migration system, sometimes it doesn't see the new field. Might be related with date field.