check whether amount is less than 0 for transfer transaction

pkg/api/transactions.go

@@ -689,6 +689,10 @@ func (a *TransactionsApi) TransactionCreateHandler(c *core.WebContext) (any, *er
 		return nil, errs.ErrTransactionDestinationAmountCannotBeSet
 	}
 
+	if transactionCreateReq.Type == models.TRANSACTION_TYPE_TRANSFER && (transactionCreateReq.SourceAmount < 0 || transactionCreateReq.DestinationAmount < 0) {
+		return nil, errs.ErrTransferTransactionAmountCannotBeLessThanZero
+	}
+
 	uid := c.GetCurrentUid()
 	user, err := a.users.GetUserById(c, uid)
 
@@ -819,6 +823,10 @@ func (a *TransactionsApi) TransactionModifyHandler(c *core.WebContext) (any, *er
 		return nil, errs.ErrTransactionTypeInvalid
 	}
 
+	if transaction.Type == models.TRANSACTION_DB_TYPE_TRANSFER_OUT && (transactionModifyReq.SourceAmount < 0 || transactionModifyReq.DestinationAmount < 0) {
+		return nil, errs.ErrTransferTransactionAmountCannotBeLessThanZero
+	}
+
 	allTransactionTagIds, err := a.transactionTags.GetAllTagIdsOfTransactions(c, uid, []int64{transaction.TransactionId})
 
 	if err != nil {

pkg/errs/transaction.go

@@ -34,4 +34,5 @@ var (
 	ErrNoDataToImport                                           = NewSystemError(NormalSubcategoryTransaction, 27, http.StatusBadRequest, "no data to import")
 	ErrCannotAddTransactionBeforeBalanceModificationTransaction = NewSystemError(NormalSubcategoryTransaction, 28, http.StatusBadRequest, "cannot add transaction before balance modification transaction")
 	ErrBalanceModificationTransactionCannotModifyTime           = NewSystemError(NormalSubcategoryTransaction, 29, http.StatusBadRequest, "balance modification transaction cannot modify transaction time")
+	ErrTransferTransactionAmountCannotBeLessThanZero            = NewNormalError(NormalSubcategoryTransaction, 30, http.StatusBadRequest, "transfer transaction amount cannot be less than zero")
 )