feat: 新增基础模型定义和交易数据仓库接口。

internal/models/models.go

@@ -31,8 +31,9 @@ const (
 	AccountTypeDebitCard  AccountType = "debit_card"
 	AccountTypeCreditCard AccountType = "credit_card"
 	AccountTypeEWallet    AccountType = "e_wallet"
-	AccountTypeCreditLine AccountType = "credit_line" // 花呗、白<EFBFBD>?
+	AccountTypeCreditLine AccountType = "credit_line" // 花呗、白条
 	AccountTypeInvestment AccountType = "investment"
+	AccountTypeReceivable AccountType = "receivable" // 应收账款（别人欠我的钱）
 )
 
 // FrequencyType represents the frequency of recurring transactions

internal/repository/transaction_repository.go

@@ -264,11 +264,15 @@ func (r *TransactionRepository) applyFilters(query *gorm.DB, filter TransactionF
 
 	// Entity filters
 	if filter.CategoryID != nil {
-		// Include sub-categories
-		var subCategoryIDs []uint
-		r.db.Model(&models.Category{}).Where("parent_id = ?", *filter.CategoryID).Pluck("id", &subCategoryIDs)
-		ids := append(subCategoryIDs, *filter.CategoryID)
-		query = query.Where("category_id IN ?", ids)
+		// Include all descendant sub-categories recursively
+		subCategoryIDs, err := r.getAllSubCategoryIDs(*filter.CategoryID)
+		if err == nil {
+			ids := append(subCategoryIDs, *filter.CategoryID)
+			query = query.Where("category_id IN ?", ids)
+		} else {
+			// Fallback: just use the specified category ID
+			query = query.Where("category_id = ?", *filter.CategoryID)
+		}
 	}
 	if filter.AccountID != nil {
 		query = query.Where("account_id = ? OR to_account_id = ?", *filter.AccountID, *filter.AccountID)
@@ -308,6 +312,29 @@ func (r *TransactionRepository) applyFilters(query *gorm.DB, filter TransactionF
 	return query
 }
 
+// getAllSubCategoryIDs recursively gets all descendant category IDs
+func (r *TransactionRepository) getAllSubCategoryIDs(parentID uint) ([]uint, error) {
+	var allIDs []uint
+	var currentLevelIDs = []uint{parentID}
+
+	// Iteratively find children level by level
+	for len(currentLevelIDs) > 0 {
+		var nextLevelIDs []uint
+		if err := r.db.Model(&models.Category{}).Where("parent_id IN ?", currentLevelIDs).Pluck("id", &nextLevelIDs).Error; err != nil {
+			return nil, err
+		}
+
+		if len(nextLevelIDs) == 0 {
+			break
+		}
+
+		allIDs = append(allIDs, nextLevelIDs...)
+		currentLevelIDs = nextLevelIDs
+	}
+
+	return allIDs, nil
+}
+
 // applySorting applies sorting to the query
 func (r *TransactionRepository) applySorting(query *gorm.DB, sort TransactionSort) *gorm.DB {
 	// Default sorting: transaction_date DESC (newest first)