Upgrading circular foreign keys from Peewee 2.7 to 3.13

[Stefano Menci]

I am upgrading an old app from Python 3.4 with Peewee 2.7.4 to Python 3.8 with Peewee 3.13.3.

The old code complains with AttributeError: Cannot use uninitialized Proxy.

# TempFile and PdfPageNumber have a circular foreign key dependency
# See http://peewee.readthedocs.org/en/latest/peewee/cookbook.html#circular-foreign-key-dependencies

PageNumberProxy = Proxy()

class TempFile(Model):
    png_page = ForeignKeyField(PageNumberProxy, null=True)

class PdfPageNumber(Model):
    pdf_file = ForeignKeyField(TempFile, backref='page_numbers')

PageNumberProxy.initialize(PdfPageNumber)

The link mentioned in the old comment is now broken. Instead I found this page that seems to be the one I'm interested on.

I changed the old code to this, it seems to be working well, but I would like a confirmation that it's the right thing to do:

class TempFile(PeeweeModel):
 png_page = peewee.DeferredForeignKey('PdfPageNumber', null=True)


class PdfPageNumber(PeeweeModel):
 pdf_file = peewee.ForeignKeyField(TempFile, backref='page_numbers')

Thanks,

Stefano

[Charles Leifer]

The docs have a section devoted to circular foreign-keys:

http://docs.peewee-orm.com/en/latest/peewee/models.html#circular-foreign-key-dependencies

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