models.py

from django.contrib.auth.models import AbstractUser
from django.db import models
from django.db.models import Avg


class UserRole(models.TextChoices):
    """Роли пользователей"""
    USER = 'user'
    MODERATOR = 'moderator'
    ADMIN = 'admin'


class User(AbstractUser):
    """Расширение стандартной модели пользователя Django"""
    bio = models.TextField(blank=True)
    email = models.EmailField(unique=True)
    role = models.CharField(
        max_length=255,
        choices=UserRole.choices,
        default=UserRole.USER
        )


class Category(models.Model):
    name = models.CharField(max_length=300, verbose_name='Категория')
    slug = models.SlugField(unique=True)


class Genre(models.Model):
    name = models.CharField(max_length=250, verbose_name='Жанр')
    slug = models.SlugField(unique=True)


class Title(models.Model):
    name = models.CharField(max_length=250, verbose_name='Название')
    year = models.PositiveSmallIntegerField(
        null=True,
        blank=True,
        db_index=True,
        verbose_name='Год'
        )
    description = models.CharField(
        max_length=2000,
        null=True,
        blank=True,
        verbose_name='Описание'
        )
    genre = models.ManyToManyField(Genre,)
    category = models.ForeignKey(
        Category, on_delete=models.SET_NULL, null=True, blank=True
    )
    rating = models.IntegerField(null=True, blank=True, verbose_name='Рейтинг')


class Review(models.Model):
    title = models.ForeignKey(
        Title,
        related_name='reviews',
        verbose_name='Произведение',
        on_delete=models.CASCADE,
    )
    text = models.TextField(verbose_name='Текст отзыва')
    author = models.ForeignKey(
        User,
        related_name='reviews',
        on_delete=models.CASCADE,
        verbose_name='Автор',
    )
    score = models.PositiveSmallIntegerField(
        verbose_name='Оценка', choices=[(r, r) for r in range(1, 11)],
    )
    pub_date = models.DateTimeField(
        verbose_name='Дата оценки', auto_now_add=True, db_index=True
    )

    def __str__(self):
        return self.text

    def save(self, *args, **kwargs):
        super().save(*args, **kwargs)
        self.score_avg = Review.objects.filter(title_id=self.title).aggregate(
            Avg('score')
        )
        self.title.rating = self.score_avg['score__avg']
        self.title.save()


class Comment(models.Model):
    """Комментарии к отзывам"""
    review = models.ForeignKey(
        Review,
        on_delete=models.CASCADE,
        related_name='comments',
        verbose_name='Отзыв'
        )
    text = models.TextField(verbose_name='Комментарий')
    author = models.ForeignKey(
        User,
        on_delete=models.CASCADE,
        related_name='comments',
        verbose_name='Автор'
        )
    pub_date = models.DateTimeField(
        'comment pub date',
        auto_now_add=True,
        db_index=True
        )