feat: Unique Constraint Violation error translator for different drivers (#6004)

* feat: duplicated key error translator for different drivers

* test: removed the dependency

* test: fixed broken tests

* refactor: added ErrorTransltor interface

* style: applied styler

---------

Co-authored-by: Saeid Saeidee <s.saeidee@sensysgatso.com>

errors.go

@@ -45,4 +45,6 @@ var (
 	ErrInvalidValueOfLength = errors.New("invalid association values, length doesn't match")
 	// ErrPreloadNotAllowed preload is not allowed when count is used
 	ErrPreloadNotAllowed = errors.New("preload is not allowed when count is used")
+	// ErrDuplicatedKey occurs when there is a unique key constraint violation
+	ErrDuplicatedKey = errors.New("duplicated key not allowed")
 )

gorm.go

@@ -347,6 +347,10 @@ func (db *DB) Callback() *callbacks {
 
 // AddError add error to db
 func (db *DB) AddError(err error) error {
+	if errTranslator, ok := db.Dialector.(ErrorTranslator); ok {
+		err = errTranslator.Translate(err)
+	}
+
 	if db.Error == nil {
 		db.Error = err
 	} else if err != nil {

interfaces.go

@@ -86,3 +86,7 @@ type Rows interface {
 	Err() error
 	Close() error
 }
+
+type ErrorTranslator interface {
+	Translate(err error) error
+}

tests/error_translator_test.go

@@ -0,0 +1,19 @@
+package tests_test
+
+import (
+	"errors"
+	"testing"
+
+	"gorm.io/gorm"
+	"gorm.io/gorm/utils/tests"
+)
+
+func TestDialectorWithErrorTranslatorSupport(t *testing.T) {
+	translatedErr := errors.New("translated error")
+	db, _ := gorm.Open(tests.DummyDialector{TranslatedErr: translatedErr})
+
+	err := db.AddError(errors.New("some random error"))
+	if !errors.Is(err, translatedErr) {
+		t.Fatalf("expected err: %v got err: %v", translatedErr, err)
+	}
+}

utils/tests/dummy_dialecter.go

@@ -8,7 +8,9 @@ import (
 	"gorm.io/gorm/schema"
 )
 
-type DummyDialector struct{}
+type DummyDialector struct {
+	TranslatedErr error
+}
 
 func (DummyDialector) Name() string {
 	return "dummy"
@@ -92,3 +94,7 @@ func (DummyDialector) Explain(sql string, vars ...interface{}) string {
 func (DummyDialector) DataTypeOf(*schema.Field) string {
 	return ""
 }
+
+func (d DummyDialector) Translate(err error) error {
+	return d.TranslatedErr
+}