Add test for second insert error (#1527)

Add test for second insert error

Reviewed-on: https://gitea.com/xorm/xorm/pulls/1527

error.go

@@ -27,7 +27,7 @@ var (
 	// ErrConditionType condition type unsupported
 	ErrConditionType = errors.New("Unsupported condition type")
 	// ErrUnSupportedSQLType parameter of SQL is not supported
-	ErrUnSupportedSQLType = errors.New("unsupported sql type")
+	ErrUnSupportedSQLType = errors.New("Unsupported sql type")
 )
 
 // ErrFieldIsNotExist columns does not exist

session_insert.go

@@ -16,6 +16,9 @@ import (
 	"xorm.io/core"
 )
 
+// ErrNoElementsOnSlice represents an error there is no element when insert
+var ErrNoElementsOnSlice = errors.New("No element on slice when insert")
+
 // Insert insert one or more beans
 func (session *Session) Insert(beans ...interface{}) (int64, error) {
 	var affected int64
@@ -67,7 +70,10 @@ func (session *Session) Insert(beans ...interface{}) (int64, error) {
 			sliceValue := reflect.Indirect(reflect.ValueOf(bean))
 			if sliceValue.Kind() == reflect.Slice {
 				size := sliceValue.Len()
-				if size > 0 {
+				if size <= 0 {
+					return 0, ErrNoElementsOnSlice
+				}
+
 				if session.engine.SupportInsertMany() {
 					cnt, err := session.innerInsertMulti(bean)
 					if err != nil {
@@ -83,7 +89,6 @@ func (session *Session) Insert(beans ...interface{}) (int64, error) {
 						affected += cnt
 					}
 				}
-				}
 			} else {
 				cnt, err := session.innerInsert(bean)
 				if err != nil {

session_insert_test.go

@@ -1067,3 +1067,38 @@ func TestInsertMultiWithOmit(t *testing.T) {
 	assert.EqualValues(t, 3, num)
 	check()
 }
+
+func TestInsertTwice(t *testing.T) {
+	assert.NoError(t, prepareEngine())
+
+	type InsertStructA struct {
+		FieldA int
+	}
+
+	type InsertStructB struct {
+		FieldB int
+	}
+
+	assert.NoError(t, testEngine.Sync2(new(InsertStructA), new(InsertStructB)))
+
+	var sliceA []InsertStructA // sliceA is empty
+	sliceB := []InsertStructB{
+		InsertStructB{
+			FieldB: 1,
+		},
+	}
+
+	ssn := testEngine.NewSession()
+	defer ssn.Close()
+
+	err := ssn.Begin()
+	assert.NoError(t, err)
+
+	_, err = ssn.Insert(sliceA)
+	assert.EqualValues(t, ErrNoElementsOnSlice, err)
+
+	_, err = ssn.Insert(sliceB)
+	assert.NoError(t, err)
+
+	assert.NoError(t, ssn.Commit())
+}