新增单词管理后台,分类有单词时禁止删除,支持 Docker 一键部署

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

backend/internal/services/category_service.go

@@ -2,11 +2,15 @@ package services
 
 import (
 	"context"
+	"errors"
 
 	"github.com/fish/language/backend/internal/models"
 	"github.com/fish/language/backend/internal/repository/queries"
 )
 
+// ErrCategoryNotEmpty is returned when deleting a category that still has words.
+var ErrCategoryNotEmpty = errors.New("category has words")
+
 // CategoryService handles business logic for categories.
 type CategoryService struct {
 	q *queries.Queries
@@ -64,8 +68,15 @@ func (s *CategoryService) Update(ctx context.Context, id int32, req models.Updat
 	return toCategory(row), nil
 }
 
-// Delete removes a category by id.
+// Delete removes a category by id. It refuses to delete a category that still has words.
 func (s *CategoryService) Delete(ctx context.Context, id int32) error {
+	count, err := s.q.CountWords(ctx, queries.CountWordsParams{CategoryID: id})
+	if err != nil {
+		return err
+	}
+	if count > 0 {
+		return ErrCategoryNotEmpty
+	}
 	return s.q.DeleteCategory(ctx, id)
 }