fix: scan array (#5624)

Co-authored-by: Jinzhu <wosmvp@gmail.com>

scan.go

@@ -243,15 +243,18 @@ func Scan(rows Rows, db *DB, mode ScanMode) {
 
 		switch reflectValue.Kind() {
 		case reflect.Slice, reflect.Array:
-			var elem reflect.Value
-			recyclableStruct := reflect.New(reflectValueType)
+			var (
+				elem             reflect.Value
+				recyclableStruct = reflect.New(reflectValueType)
+				isArrayKind      = reflectValue.Kind() == reflect.Array
+			)
 
 			if !update || reflectValue.Len() == 0 {
 				update = false
 				// if the slice cap is externally initialized, the externally initialized slice is directly used here
 				if reflectValue.Cap() == 0 {
 					db.Statement.ReflectValue.Set(reflect.MakeSlice(reflectValue.Type(), 0, 20))
-				} else {
+				} else if !isArrayKind {
 					reflectValue.SetLen(0)
 					db.Statement.ReflectValue.Set(reflectValue)
 				}
@@ -285,10 +288,15 @@ func Scan(rows Rows, db *DB, mode ScanMode) {
 				db.scanIntoStruct(rows, elem, values, fields, joinFields)
 
 				if !update {
-					if isPtr {
-						reflectValue = reflect.Append(reflectValue, elem)
+					if !isPtr {
+						elem = elem.Elem()
+					}
+					if isArrayKind {
+						if reflectValue.Len() >= int(db.RowsAffected) {
+							reflectValue.Index(int(db.RowsAffected - 1)).Set(elem)
+						}
 					} else {
-						reflectValue = reflect.Append(reflectValue, elem.Elem())
+						reflectValue = reflect.Append(reflectValue, elem)
 					}
 				}
 			}

tests/query_test.go

@@ -216,6 +216,30 @@ func TestFind(t *testing.T) {
 		}
 	}
 
+	// test array
+	var models2 [3]User
+	if err := DB.Where("name in (?)", []string{"find"}).Find(&models2).Error; err != nil || len(models2) != 3 {
+		t.Errorf("errors happened when query find with in clause: %v, length: %v", err, len(models2))
+	} else {
+		for idx, user := range users {
+			t.Run("FindWithInClause#"+strconv.Itoa(idx+1), func(t *testing.T) {
+				CheckUser(t, models2[idx], user)
+			})
+		}
+	}
+
+	// test smaller array
+	var models3 [2]User
+	if err := DB.Where("name in (?)", []string{"find"}).Find(&models3).Error; err != nil || len(models3) != 2 {
+		t.Errorf("errors happened when query find with in clause: %v, length: %v", err, len(models3))
+	} else {
+		for idx, user := range users[:2] {
+			t.Run("FindWithInClause#"+strconv.Itoa(idx+1), func(t *testing.T) {
+				CheckUser(t, models3[idx], user)
+			})
+		}
+	}
+
 	var none []User
 	if err := DB.Where("name in (?)", []string{}).Find(&none).Error; err != nil || len(none) != 0 {
 		t.Errorf("errors happened when query find with in clause and zero length parameter: %v, length: %v", err, len(none))