Django 3 Web Development Cookbook - Fourth Edition

How to do it...

The following steps will show you how to switch from a foreign key relation to a many-to-many relation, while preserving the already existing data:

1. Add a new many-to-many field, called categories, as follows:

# myproject/apps/ideas/models.pyfrom django.db import modelsfrom django.conf import settingsfrom django.utils.translation import gettext_lazy as _from myproject.apps.core.model_fields import (    MultilingualCharField,    MultilingualTextField,)class Idea(models.Model):    title = MultilingualCharField(        _("Title"),        max_length=200,    )    content = MultilingualTextField(        _("Content"),    )    category = models.ForeignKey(        "categories.Category",        verbose_name=_("Category"),        blank=True,        null=True,        on_delete=models.SET_NULL, related_name="category_ideas", ...