feat: add pagination and color filter to catalog view and templates

- Implemented pagination for catalog items with Django's Paginator
- Updated `item-list.html` to include pagination controls
- Added color filtering logic to catalog view with support for `Color` model
- Enhanced `side-bar.html` with a dynamic color dropdown filter
- Adjusted filtering URL logic to accommodate color filters and pagination parameters
- Prefetched `colors` in item queries to optimize performance

items/views.py

@@ -2,11 +2,12 @@ from dataclasses import dataclass
 from decimal import Decimal, InvalidOperation
 from urllib.parse import urlencode
 
+from django.core.paginator import Paginator
 from django.http import HttpRequest, HttpResponse, Http404
 from django.shortcuts import redirect, render
 
 from favorites.services import get_user_favorite_item_ids
-from items.models import Category, Item, Subcategory
+from items.models import Category, Color, Item, Subcategory
 from orders.services import get_user_cart_item_ids
 
 
@@ -45,6 +46,7 @@ def _build_catalog_url(
     max_price: str = "",
     sale: bool = False,
     new: bool = False,
+    color: str = "",
 ) -> str:
     base_url = "/catalog/"
     if category_slug:
@@ -63,6 +65,8 @@ def _build_catalog_url(
         query_params["sale"] = "1"
     if new:
         query_params["new"] = "1"
+    if color:
+        query_params["color"] = color
 
     if not query_params:
         return base_url
@@ -100,6 +104,7 @@ def index(request: HttpRequest, category: str | None = None) -> HttpResponse:
     selected_scope = request.GET.get('category', '').strip()
     filter_sale = request.GET.get('sale') == '1'
     filter_new = request.GET.get('new') == '1'
+    selected_color_id_raw = request.GET.get('color', '').strip()
 
     if category is None and selected_scope:
         category_slug, selected_subcategory_slug = _resolve_catalog_scope(selected_scope)
@@ -113,12 +118,13 @@ def index(request: HttpRequest, category: str | None = None) -> HttpResponse:
                     max_price=max_price_raw,
                     sale=filter_sale,
                     new=filter_new,
+                    color=selected_color_id_raw,
                 )
             )
 
     items = (
         Item.objects.select_related('category', 'subcategory')
-        .prefetch_related('images')
+        .prefetch_related('images', 'colors')
         .order_by('category__name', 'name')
     )
 
@@ -159,6 +165,16 @@ def index(request: HttpRequest, category: str | None = None) -> HttpResponse:
     if filter_new:
         items = [item for item in items if item.is_new]
 
+    color_item_ids = {c.id for item in items for c in item.colors.all()}
+    available_colors = list(Color.objects.filter(id__in=color_item_ids))
+
+    if selected_color_id_raw:
+        try:
+            selected_color_id_int = int(selected_color_id_raw)
+            items = [item for item in items if any(c.id == selected_color_id_int for c in item.colors.all())]
+        except ValueError:
+            pass
+
     item_prices = [item.display_price for item in items]
     slider_min_bound = min(item_prices, default=Decimal('0'))
     slider_max_bound = max(item_prices, default=slider_min_bound)
@@ -176,6 +192,13 @@ def index(request: HttpRequest, category: str | None = None) -> HttpResponse:
     slider_selected_min = min(max(slider_selected_min, slider_min_bound), slider_max_bound)
     slider_selected_max = min(max(slider_selected_max, slider_min_bound), slider_max_bound)
 
+    page_number = request.GET.get('page', 1)
+    paginator = Paginator(items, 24)
+    page_obj = paginator.get_page(page_number)
+
+    pagination_params = {k: v for k, v in request.GET.items() if k != 'page'}
+    pagination_query_string = urlencode(pagination_params)
+
     categories = list(Category.objects.order_by('name'))
     all_items_url = _build_catalog_url(
         search_query=search_query,
@@ -183,6 +206,7 @@ def index(request: HttpRequest, category: str | None = None) -> HttpResponse:
         max_price=max_price_raw,
         sale=filter_sale,
         new=filter_new,
+        color=selected_color_id_raw,
     )
     for catalog_category in categories:
         catalog_category.catalog_url = _build_catalog_url(
@@ -192,6 +216,7 @@ def index(request: HttpRequest, category: str | None = None) -> HttpResponse:
             max_price=max_price_raw,
             sale=filter_sale,
             new=filter_new,
+            color=selected_color_id_raw,
         )
 
     subcategories = list(subcategories)
@@ -204,6 +229,7 @@ def index(request: HttpRequest, category: str | None = None) -> HttpResponse:
             max_price=max_price_raw,
             sale=filter_sale,
             new=filter_new,
+            color=selected_color_id_raw,
         )
         for catalog_subcategory in subcategories:
             catalog_subcategory.catalog_url = _build_catalog_url(
@@ -214,6 +240,7 @@ def index(request: HttpRequest, category: str | None = None) -> HttpResponse:
                 max_price=max_price_raw,
                 sale=filter_sale,
                 new=filter_new,
+                color=selected_color_id_raw,
             )
 
     price_filter_action = _build_catalog_url(selected_category.id)
@@ -235,6 +262,11 @@ def index(request: HttpRequest, category: str | None = None) -> HttpResponse:
         'categories': categories,
         'subcategories': subcategories,
         'items': items,
+        'page_obj': page_obj,
+        'paginator': paginator,
+        'pagination_query_string': pagination_query_string,
+        'available_colors': available_colors,
+        'selected_color_id': selected_color_id_raw,
         'selected_category': selected_category,
         'selected_subcategory': selected_subcategory,
         'all_items_url': all_items_url,

templates/catalog/_fragments/item-list.html

@@ -1,3 +1,18 @@
 <main class="item-list">
-    {% include "_fragments/item-grid.html" with items=items empty_message="В этой категории пока нет товаров." %}
+    {% include "_fragments/item-grid.html" with items=page_obj empty_message="В этой категории пока нет товаров." %}
+
+    {% if paginator.num_pages > 1 %}
+    <nav class="catalog-pagination">
+        {% if page_obj.has_previous %}
+            <a href="?{{ pagination_query_string }}&page={{ page_obj.previous_page_number }}" class="catalog-pagination__btn">&laquo;</a>
+        {% endif %}
+        {% for i in paginator.page_range %}
+            <a href="?{{ pagination_query_string }}&page={{ i }}"
+               class="catalog-pagination__btn {% if i == page_obj.number %}active{% endif %}">{{ i }}</a>
+        {% endfor %}
+        {% if page_obj.has_next %}
+            <a href="?{{ pagination_query_string }}&page={{ page_obj.next_page_number }}" class="catalog-pagination__btn">&raquo;</a>
+        {% endif %}
+    </nav>
+    {% endif %}
 </main>

templates/catalog/_fragments/side-bar.html

@@ -85,13 +85,19 @@
             <button type="submit" class="catalog-filter-submit">Применить</button>
         </section>
 
+        {% if available_colors %}
         <section class="a-section color-section">
             <h2>Цвет</h2>
+            <select name="color" onchange="this.form.submit()">
+                <option value="">Любой</option>
+                {% for color in available_colors %}
+                    <option value="{{ color.id }}" {% if selected_color_id == color.id|stringformat:"i" %}selected{% endif %}>
+                        {{ color.name }}
+                    </option>
+                {% endfor %}
+            </select>
         </section>
-
-        <section class="a-section material-section">
-            <h2>Материал</h2>
-        </section>
+        {% endif %}
     </form>
 
     <section class="a-section promotions-section">