Django 3.1 Makemigrations fails with FilePathField but succeeds with CharField

Converting path from Pathlib to str, allowed makemigrations to pass, at the cost of having a single test to rewrite

class Firmware(models.Model):

    filepath = models.FilePathField(path=str(settings.VENDOR_STATIC_ROOT), match=settings.FIRMWARE_REGEX, recursive=True)
    display_name = models.CharField(default='foobar', max_length=32, help_text='Value as shown in HTTP User-Agent string')

    def __str__(self):
        return self.relative_path()

    def relative_path(self):
        return str(pathlib.Path(self.filepath).relative_to(settings.VENDOR_STATIC_ROOT))

I would be very curious to get a deeper understanding of what is happening here.

Thanks in advance.

Le jeudi 18 mars 2021 à 16:51:13 UTC+1, Olivier a écrit :

PS: In case the errors comes from the  '/var/www/vhosts/foo/vendorstatic' value itself , may I add that VENDOR_STATIC_ROOT is defined in settings.py, with:

from pathlib import Path

BASE_DIR = Path(__file__).resolve(strict=True).parent.parent

VENDOR_STATIC_ROOT = BASE_DIR / 'vendorstatic'

and that /var/www/vhosts/foo/vendorstatic directory exists.

Python version 3.7.3 and Django 3.1.7.

Le jeudi 18 mars 2021 à 15:28:21 UTC+1, Olivier a écrit :

Hello,

I've got a Django app which has over 200 migration steps.

To shorten its test loading time, I'm trying to erase all current migrations and restart from scratch.

I deteted and re-created my app Postgres database.

I deleted all files (but __init__.py) in migrations directory.

I typed "python manage.py makemigrations --verbosity 3".

1. Latest makemigrations failed with:

  File "/home/perenip/venv-flexcore/lib/python3.7/site-packages/django/db/migrations/serializer.py", line 339, in serializer_factory
    "topics/migrations/#migration-serializing" % (value, get_docs_version())
ValueError: Cannot serialize: PosixPath('/var/www/vhosts/foo/vendorstatic')
There are some values Django cannot serialize into migration files.
For more, see https://docs.djangoproject.com/en/3.1/topics/migrations/#migration-serializing

If I'm not mistaken, I couldn't read any reference to the Model/Field that triggered the error.

Should we expect an explicit mention of the faulty statement/line ?

2. I edited a Model within models.py with:

class Firmware(models.Model):
    #filepath = models.FilePathField(path=settings.VENDOR_STATIC_ROOT, match=settings.FIRMWARE_REGEX, recursive=True)
    filepath = models.CharField(max_length=64)
    display_name = models.CharField(default='foobar', max_length=32, help_text='Value as shown in HTTP User-Agent string')

    def __str__(self):
        return self.relative_path()

    def relative_path(self):
        return str(pathlib.Path(self.filepath).relative_to(settings.VENDOR_STATIC_ROOT))

After changing from a PathFileField to a CharFiled as shown above, I could successfully run makemigrations.

Doc [1] mentions Django can serialize "any Django field". Should it serialize FilePathField ?

[1] https://docs.djangoproject.com/en/3.1/topics/migrations/#migration-serializing

3. How to work around this with rewriting my app (and its tests) ?

Best regards

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