manytomany relationships to define a manytomany relationship use manytomanyfield in this example an article can be published in multiple publication objects and a publication has multiple article objects assign a string as name to make sure the intermediary model is correctly created refs 20207 models to test correct relatedname inheritance assign a string as name to make sure the intermediary model is correctly created refs 20207 models to test correct related_name inheritance
from django.db import models


class Publication(models.Model):
    title = models.CharField(max_length=30)

    class Meta:
        ordering = ("title",)

    def __str__(self):
        return self.title


class Tag(models.Model):
    id = models.BigAutoField(primary_key=True)
    name = models.CharField(max_length=50)

    def __str__(self):
        return self.name


class NoDeletedArticleManager(models.Manager):
    def get_queryset(self):
        return super().get_queryset().exclude(headline="deleted")


class Article(models.Model):
    headline = models.CharField(max_length=100)
    
    
    publications = models.ManyToManyField(Publication, name="publications")
    tags = models.ManyToManyField(Tag, related_name="tags")
    authors = models.ManyToManyField("User", through="UserArticle")

    objects = NoDeletedArticleManager()

    class Meta:
        ordering = ("headline",)

    def __str__(self):
        return self.headline


class User(models.Model):
    username = models.CharField(max_length=20, unique=True)

    def __str__(self):
        return self.username


class UserArticle(models.Model):
    user = models.ForeignKey(User, models.CASCADE, to_field="username")
    article = models.ForeignKey(Article, models.CASCADE)



class AbstractArticle(models.Model):
    class Meta:
        abstract = True

    publications = models.ManyToManyField(
        Publication, name="publications", related_name="+"
    )


class InheritedArticleA(AbstractArticle):
    pass


class InheritedArticleB(AbstractArticle):
    pass