feat(material): 新增 H5 大类/种类聚合查询接口

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/apps/material/views.py

@@ -7,6 +7,7 @@ from openpyxl import Workbook
 from openpyxl.worksheet.datavalidation import DataValidation
 from openpyxl.styles import Alignment, Border, Font, PatternFill, Side
 from openpyxl.utils import get_column_letter
+from django.db.models import Count
 from rest_framework import generics, status
 from rest_framework.decorators import api_view, action
 from rest_framework.permissions import IsAuthenticated
@@ -483,6 +484,37 @@ class MaterialViewSet(ModelViewSet):
 
         return Response(result)
 
+    @action(detail=False, methods=['get'], url_path='categories-by-major')
+    def categories_by_major(self, request):
+        major = request.query_params.get('major_category')
+        if not major:
+            return Response({"detail": "major_category 参数必填"}, status=status.HTTP_400_BAD_REQUEST)
+        qs = (Material.objects
+              .filter(major_category=major, status='approved')
+              .exclude(material_category__isnull=True)
+              .exclude(material_category__exact='')
+              .values('material_category')
+              .annotate(count=Count('id'))
+              .order_by('material_category'))
+        data = [{"value": row['material_category'], "count": row['count']} for row in qs]
+        return Response(data)
+
+    @action(detail=False, methods=['get'], url_path='subcategories-by-category')
+    def subcategories_by_category(self, request):
+        major = request.query_params.get('major_category')
+        category = request.query_params.get('material_category')
+        if not major or not category:
+            return Response({"detail": "major_category 和 material_category 均必填"}, status=status.HTTP_400_BAD_REQUEST)
+        qs = (Material.objects
+              .filter(major_category=major, material_category=category, status='approved')
+              .exclude(material_subcategory__isnull=True)
+              .exclude(material_subcategory__exact='')
+              .values('material_subcategory')
+              .annotate(count=Count('id'))
+              .order_by('material_subcategory'))
+        data = [{"value": row['material_subcategory'], "count": row['count']} for row in qs]
+        return Response(data)
+
 
 class MaterialCategoryViewSet(ModelViewSet):
     """