feat: add favorites feature for users

- Implemented `Favorite` model with unique user-item constraint and timestamped records
- Added `favorites:index` and `favorites:toggle` views with AJAX support for toggling favorites
- Built templates and front-end assets for the favorites page and integration with item grids
- Extended header with favorites link and dynamic counter
- Added tests covering models, views, and templates for the favorites functionality
- Updated admin to enable management of favorites via Django admin interface

favorites/__init__.py

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+

favorites/admin.py

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+from django.contrib import admin
+
+from .models import Favorite
+
+
+@admin.register(Favorite)
+class FavoriteAdmin(admin.ModelAdmin):
+    list_display = ("user", "item", "created_at")
+    list_filter = ("created_at",)
+    search_fields = ("user__username", "user__email", "item__name", "item__slug")
+

favorites/apps.py

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+from django.apps import AppConfig
+
+
+class FavoritesConfig(AppConfig):
+    default_auto_field = "django.db.models.BigAutoField"
+    name = "favorites"
+

favorites/migrations/0001_initial.py

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+# Generated by Django 6.0.4 on 2026-05-10 17:49
+
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ('items', '0003_subcategory_item_subcategory_and_more'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Favorite',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('created_at', models.DateTimeField(auto_now_add=True, verbose_name='Дата добавления')),
+                ('item', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='favorite_entries', to='items.item', verbose_name='Товар')),
+                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='favorite_entries', to=settings.AUTH_USER_MODEL, verbose_name='Пользователь')),
+            ],
+            options={
+                'verbose_name': 'Избранный товар',
+                'verbose_name_plural': 'Избранные товары',
+                'ordering': ('-created_at', '-id'),
+                'constraints': [models.UniqueConstraint(fields=('user', 'item'), name='unique_favorite_user_item')],
+            },
+        ),
+    ]

favorites/migrations/__init__.py

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+

favorites/models.py

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+from django.conf import settings
+from django.db import models
+
+from items.models import Item
+
+
+class Favorite(models.Model):
+    user = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.CASCADE,
+        related_name="favorite_entries",
+        verbose_name="Пользователь",
+    )
+    item = models.ForeignKey(
+        Item,
+        on_delete=models.CASCADE,
+        related_name="favorite_entries",
+        verbose_name="Товар",
+    )
+    created_at = models.DateTimeField(auto_now_add=True, verbose_name="Дата добавления")
+
+    class Meta:
+        ordering = ("-created_at", "-id")
+        constraints = [
+            models.UniqueConstraint(fields=("user", "item"), name="unique_favorite_user_item"),
+        ]
+        verbose_name = "Избранный товар"
+        verbose_name_plural = "Избранные товары"
+
+    def __str__(self):
+        return f"{self.user} -> {self.item}"
+

favorites/services.py

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+from typing import Any
+
+from favorites.models import Favorite
+
+
+def get_user_favorite_item_ids(user: Any) -> set[int]:
+    if not user.is_authenticated:
+        return set()
+
+    return set(
+        Favorite.objects.filter(user=user).values_list("item_id", flat=True)
+    )

favorites/tests.py

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+from django.contrib.auth import get_user_model
+from django.db import IntegrityError
+from django.test import TestCase
+from django.urls import reverse
+
+from favorites.models import Favorite
+from items.models import Category, Item, ItemImage, Subcategory
+
+
+User = get_user_model()
+
+
+class FavoritePageTests(TestCase):
+    def setUp(self):
+        self.user = User.objects.create_user(
+            username="marina",
+            email="marina@example.com",
+            password="StrongPassword123",
+            is_active=True,
+        )
+        self.plumbing = Category.objects.create(name="Сантехника", slug="plumbing")
+        self.sinks = Subcategory.objects.create(name="Мойки", slug="sinks", category=self.plumbing)
+        self.taps = Subcategory.objects.create(name="Смесители", slug="taps", category=self.plumbing)
+        self.sink = Item.objects.create(
+            name="Кухонная мойка",
+            slug="kitchen-sink",
+            category=self.plumbing,
+            subcategory=self.sinks,
+            description="Искусственный камень",
+            price="1600.00",
+            is_available=True,
+        )
+        self.tap = Item.objects.create(
+            name="Смеситель Mono",
+            slug="mono-tap",
+            category=self.plumbing,
+            subcategory=self.taps,
+            description="Однорычажный смеситель",
+            price="320.00",
+            is_available=False,
+        )
+
+    def test_favorites_page_redirects_unauthenticated_users(self):
+        response = self.client.get(reverse("favorites:index"))
+
+        self.assertEqual(response.status_code, 302)
+        self.assertIn(reverse("users:login"), response["Location"])
+
+    def test_favorites_page_shows_empty_state(self):
+        self.client.force_login(self.user)
+
+        response = self.client.get(reverse("favorites:index"))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "В избранном пока нет товаров.")
+
+    def test_favorites_page_shows_items_in_tile_grid(self):
+        self.client.force_login(self.user)
+        ItemImage.objects.create(
+            item=self.sink,
+            image="items/sink-primary.jpg",
+            alt="Главное фото мойки",
+            sort_order=0,
+            is_primary=True,
+        )
+        Favorite.objects.create(user=self.user, item=self.tap)
+        Favorite.objects.create(user=self.user, item=self.sink)
+
+        response = self.client.get(reverse("favorites:index"))
+
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "Избранное")
+        self.assertContains(response, "Кухонная мойка")
+        self.assertContains(response, "Смеситель Mono")
+        self.assertContains(response, "/media/items/sink-primary.jpg")
+        self.assertContains(response, 'href="/catalog/plumbing/kitchen-sink/"', html=False)
+        self.assertContains(response, 'href="/catalog/plumbing/mono-tap/"', html=False)
+        self.assertContains(response, "Удалить из избранного")
+
+    def test_toggle_endpoint_adds_and_removes_favorite(self):
+        self.client.force_login(self.user)
+
+        add_response = self.client.post(
+            reverse("favorites:toggle"),
+            data={"item_id": self.sink.pk, "next": reverse("favorites:index")},
+        )
+
+        self.assertRedirects(add_response, reverse("favorites:index"))
+        self.assertTrue(Favorite.objects.filter(user=self.user, item=self.sink).exists())
+
+        remove_response = self.client.post(
+            reverse("favorites:toggle"),
+            data={"item_id": self.sink.pk, "next": reverse("favorites:index")},
+        )
+
+        self.assertRedirects(remove_response, reverse("favorites:index"))
+        self.assertFalse(Favorite.objects.filter(user=self.user, item=self.sink).exists())
+
+    def test_toggle_endpoint_returns_json_for_ajax_requests(self):
+        self.client.force_login(self.user)
+
+        response = self.client.post(
+            reverse("favorites:toggle"),
+            data={"item_id": self.sink.pk, "next": reverse("favorites:index")},
+            HTTP_X_REQUESTED_WITH="XMLHttpRequest",
+            HTTP_ACCEPT="application/json",
+        )
+
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response["Content-Type"], "application/json")
+        self.assertEqual(response.json()["item_id"], self.sink.pk)
+        self.assertTrue(response.json()["is_favorite"])
+        self.assertEqual(response.json()["favorite_count"], 1)
+        self.assertTrue(Favorite.objects.filter(user=self.user, item=self.sink).exists())
+
+    def test_favorite_pair_is_unique_per_user_and_item(self):
+        Favorite.objects.create(user=self.user, item=self.sink)
+
+        with self.assertRaises(IntegrityError):
+            Favorite.objects.create(user=self.user, item=self.sink)

favorites/urls.py

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+from django.urls import path
+
+from favorites import views
+
+app_name = "favorites"
+
+urlpatterns = [
+    path("", views.index, name="index"),
+    path("toggle/", views.toggle, name="toggle"),
+]

favorites/views.py

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+from django.contrib import messages
+from django.contrib.auth.decorators import login_required
+from django.http import HttpRequest, HttpResponse, JsonResponse
+from django.shortcuts import get_object_or_404, redirect, render
+from django.urls import reverse
+from django.utils.http import url_has_allowed_host_and_scheme
+from django.views.decorators.http import require_POST
+
+from favorites.models import Favorite
+from items.models import Item
+
+
+def wants_json_response(request: HttpRequest) -> bool:
+    return (
+        request.headers.get("x-requested-with") == "XMLHttpRequest"
+        or "application/json" in request.headers.get("accept", "")
+    )
+
+
+@login_required
+def index(request: HttpRequest) -> HttpResponse:
+    favorite_records = (
+        Favorite.objects.filter(user=request.user)
+        .select_related("item__category", "item__subcategory")
+        .prefetch_related("item__images")
+        .order_by("-created_at", "-id")
+    )
+    items = [favorite.item for favorite in favorite_records]
+
+    return render(request, "favorites/index.html", {
+        "items": items,
+        "favorite_count": len(items),
+        "favorite_item_ids": {item.id for item in items},
+    })
+
+
+@login_required
+@require_POST
+def toggle(request: HttpRequest) -> HttpResponse:
+    item_id = request.POST.get("item_id")
+    item = get_object_or_404(Item, pk=item_id)
+
+    favorite = Favorite.objects.filter(user=request.user, item=item).first()
+    if favorite:
+        favorite.delete()
+        is_favorite = False
+        message = f"Товар «{item.name}» удалён из избранного."
+    else:
+        Favorite.objects.create(user=request.user, item=item)
+        is_favorite = True
+        message = f"Товар «{item.name}» добавлен в избранное."
+
+    favorite_count = Favorite.objects.filter(user=request.user).count()
+    next_url = request.POST.get("next") or reverse("favorites:index")
+
+    if wants_json_response(request):
+        return JsonResponse({
+            "item_id": item.pk,
+            "is_favorite": is_favorite,
+            "favorite_count": favorite_count,
+            "message": message,
+        })
+
+    messages.success(request, message)
+
+    if not url_has_allowed_host_and_scheme(
+        next_url,
+        allowed_hosts={request.get_host()},
+        require_https=request.is_secure(),
+    ):
+        next_url = reverse("favorites:index")
+
+    return redirect(next_url)