from django.db import models
from django.contrib.auth.models import User

class Article(models.Model):
    title = models.CharField(max_length=200)
    content = models.TextField()
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    published = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    tags = models.ManyToManyField('Tag', blank=True)

    class Meta:
        ordering = ['-created_at']
        indexes = [models.Index(fields=['title', 'published'])]

    def __str__(self):
        return self.title

    @property
    def summary(self):
        return self.content[:200] + "..."

class Tag(models.Model):
    name = models.SlugField(unique=True)

    def __str__(self):
        return self.name

from django.db.models import Count, Q, Avg, Prefetch

# Basic queries
articles = Article.objects.filter(published=True)
recent = Article.objects.order_by('-created_at')[:10]

# Complex filtering
popular = Article.objects.filter(
    Q(published=True) & Q(title__icontains='python')
).exclude(author__username='test')

# Aggregation
stats = Article.objects.aggregate(
    total=Count('id'),
    avg_length=Avg('content__len')
)

# Prefetch related (avoid N+1)
articles_with_tags = Article.objects.prefetch_related(
    Prefetch('tags', queryset=Tag.objects.only('name'))
).select_related('author')

# Bulk operations
Article.objects.filter(published=False).update(published=True)
Article.objects.bulk_create([
    Article(title=f"Article {i}", content="...") for i in range(100)
])

from django.views.generic import ListView, DetailView

class ArticleListView(ListView):
    model = Article
    paginate_by = 20

    def get_queryset(self):
        return super().get_queryset().filter(
            published=True
        ).select_related('author').prefetch_related('tags')