*datatypes.JSON in model causes panic on tx.Statement.Changed (#6611)

* do not panic on nil

* more explanation in comments

* get things compact

utils/utils.go

@@ -89,19 +89,28 @@ func Contains(elems []string, elem string) bool {
 	return false
 }
 
-func AssertEqual(src, dst interface{}) bool {
-	if !reflect.DeepEqual(src, dst) {
-		if valuer, ok := src.(driver.Valuer); ok {
-			src, _ = valuer.Value()
-		}
+func AssertEqual(x, y interface{}) bool {
+	if reflect.DeepEqual(x, y) {
+		return true
+	}
+	if x == nil || y == nil {
+		return false
+	}
 
-		if valuer, ok := dst.(driver.Valuer); ok {
-			dst, _ = valuer.Value()
-		}
+	xval := reflect.ValueOf(x)
+	yval := reflect.ValueOf(y)
+	if xval.Kind() == reflect.Ptr && xval.IsNil() ||
+		yval.Kind() == reflect.Ptr && yval.IsNil() {
+		return false
+	}
 
-		return reflect.DeepEqual(src, dst)
+	if valuer, ok := x.(driver.Valuer); ok {
+		x, _ = valuer.Value()
+	}
+	if valuer, ok := y.(driver.Valuer); ok {
+		y, _ = valuer.Value()
 	}
-	return true
+	return reflect.DeepEqual(x, y)
 }
 
 func ToString(value interface{}) string {

utils/utils_test.go

@@ -98,6 +98,7 @@ func TestAssertEqual(t *testing.T) {
 		{"error not equal", errors.New("1"), errors.New("2"), false},
 		{"driver.Valuer equal", ModifyAt{Time: now, Valid: true}, ModifyAt{Time: now, Valid: true}, true},
 		{"driver.Valuer not equal", ModifyAt{Time: now, Valid: true}, ModifyAt{Time: now.Add(time.Second), Valid: true}, false},
+		{"driver.Valuer equal (ptr to nil ptr)", (*ModifyAt)(nil), &ModifyAt{}, false},
 	}
 	for _, test := range assertEqualTests {
 		t.Run(test.name, func(t *testing.T) {