[NOD-324] Properly handle GORM errors in API server (#409)

* [NOD-324] Properly handle GORM errors in API server

* [NOD-324] Handle RecordNotFound error in GetBlockByHashHandler

* [NOD-324] Make a separate function for NewErrorFromDBErrors

apiserver/controllers/block.go

@@ -38,10 +38,13 @@ func GetBlockByHashHandler(blockHash string) (interface{}, *utils.HandlerError)
 	}
 
 	block := &models.Block{}
-	db.Where(&models.Block{BlockHash: blockHash}).Preload("AcceptingBlock").First(block)
+	dbResult := db.Where(&models.Block{BlockHash: blockHash}).Preload("AcceptingBlock").First(block)
-	if block.ID == 0 {
+	if dbResult.RecordNotFound() && len(dbResult.GetErrors()) == 1 {
 		return nil, utils.NewHandlerError(http.StatusNotFound, "No block with the given block hash was found.")
 	}
+	if len(dbResult.GetErrors()) > 0 {
+		return nil, utils.NewHandlerErrorFromDBErrors("Some errors where encountered when loading transactions from the database:", dbResult.GetErrors())
+	}
 	return convertBlockModelToBlockResponse(block), nil
 }
 

apiserver/controllers/transaction.go

@@ -28,10 +28,13 @@ func GetTransactionByIDHandler(txID string) (interface{}, *utils.HandlerError) {
 
 	tx := &models.Transaction{}
 	query := db.Where(&models.Transaction{TransactionID: txID})
-	addTxPreloadedFields(query).First(&tx)
+	dbResult := addTxPreloadedFields(query).First(&tx)
-	if tx.ID == 0 {
+	if dbResult.RecordNotFound() && len(dbResult.GetErrors()) == 1 {
 		return nil, utils.NewHandlerError(http.StatusNotFound, "No transaction with the given txid was found.")
 	}
+	if len(dbResult.GetErrors()) > 0 {
+		return nil, utils.NewHandlerErrorFromDBErrors("Some errors where encountered when loading transaction from the database:", dbResult.GetErrors())
+	}
 	return convertTxModelToTxResponse(tx), nil
 }
 
@@ -49,10 +52,13 @@ func GetTransactionByHashHandler(txHash string) (interface{}, *utils.HandlerErro
 
 	tx := &models.Transaction{}
 	query := db.Where(&models.Transaction{TransactionHash: txHash})
-	addTxPreloadedFields(query).First(&tx)
+	dbResult := addTxPreloadedFields(query).First(&tx)
-	if tx.ID == 0 {
+	if dbResult.RecordNotFound() && len(dbResult.GetErrors()) == 1 {
 		return nil, utils.NewHandlerError(http.StatusNotFound, "No transaction with the given txhash was found.")
 	}
+	if len(dbResult.GetErrors()) > 0 {
+		return nil, utils.NewHandlerErrorFromDBErrors("Some errors where encountered when loading transaction from the database:", dbResult.GetErrors())
+	}
 	return convertTxModelToTxResponse(tx), nil
 }
 
@@ -81,7 +87,10 @@ func GetTransactionsByAddressHandler(address string, skip uint64, limit uint64)
 		Limit(limit).
 		Offset(skip).
 		Order("`transactions`.`id` ASC")
-	addTxPreloadedFields(query).Find(&txs)
+	dbErrors := addTxPreloadedFields(query).Find(&txs).GetErrors()
+	if len(dbErrors) > 0 {
+		return nil, utils.NewHandlerErrorFromDBErrors("Some errors where encountered when loading transactions from the database:", dbErrors)
+	}
 	txResponses := make([]*transactionResponse, len(txs))
 	for i, tx := range txs {
 		txResponses[i] = convertTxModelToTxResponse(tx)
@@ -97,11 +106,14 @@ func GetUTXOsByAddressHandler(address string) (interface{}, *utils.HandlerError)
 	}
 
 	var transactionOutputs []*models.TransactionOutput
-	db.
+	dbErrors := db.
 		Joins("LEFT JOIN `addresses` ON `addresses`.`id` = `transaction_outputs`.`address_id`").
 		Where("`addresses`.`address` = ? AND `transaction_outputs`.`is_spent` = 0", address).
 		Preload("Transaction.AcceptingBlock").
-		Find(&transactionOutputs)
+		Find(&transactionOutputs).GetErrors()
+	if len(dbErrors) > 0 {
+		return nil, utils.NewHandlerErrorFromDBErrors("Some errors where encountered when loading UTXOs from the database:", dbErrors)
+	}
 
 	UTXOsResponses := make([]*transactionOutputResponse, len(transactionOutputs))
 	for i, transactionOutput := range transactionOutputs {

apiserver/utils/error.go

@@ -1,6 +1,10 @@
 package utils
 
-import "net/http"
+import (
+	"fmt"
+	"net/http"
+	"strings"
+)
 
 // HandlerError is an error returned from
 // a rest route handler or a middleware.
@@ -39,3 +43,21 @@ func NewHandlerErrorWithCustomClientMessage(code int, message, clientMessage str
 func NewInternalServerHandlerError(message string) *HandlerError {
 	return NewHandlerErrorWithCustomClientMessage(http.StatusInternalServerError, message, http.StatusText(http.StatusInternalServerError))
 }
+
+// NewErrorFromDBErrors takes a slice of database errors and a prefix, and
+// returns an error with all of the database errors formatted to one string with
+// the given prefix
+func NewErrorFromDBErrors(prefix string, dbErrors []error) error {
+	dbErrorsStrings := make([]string, len(dbErrors))
+	for i, dbErr := range dbErrors {
+		dbErrorsStrings[i] = fmt.Sprintf("\"%s\"", dbErr)
+	}
+	return fmt.Errorf("%s [%s]", prefix, strings.Join(dbErrorsStrings, ","))
+}
+
+// NewHandlerErrorFromDBErrors takes a slice of database errors and a prefix, and
+// returns an HandlerError with error code http.StatusInternalServerError with
+// all of the database errors formatted to one string with the given prefix
+func NewHandlerErrorFromDBErrors(prefix string, dbErrors []error) *HandlerError {
+	return NewInternalServerHandlerError(NewErrorFromDBErrors(prefix, dbErrors).Error())
+}