isnull filter needs boolean value for the Filter function

g_appcode.go

@@ -1062,8 +1062,16 @@ func GetAll{{modelName}}(query map[string]string, fields []string, sortby []stri
 	for k, v := range query {
 		// rewrite dot-notation to Object__Attribute
 		k = strings.Replace(k, ".", "__", -1)
+		if strings.Contains(k, "isnull") {
+			var v2 bool
+			if v == "true" || v == "1" {
+				v2 = true
+			}
+			qs = qs.Filter(k, v2)
+		} else {
 			qs = qs.Filter(k, v)
 		}
+	}
 	// order by:
 	var sortFields []string
 	if len(sortby) != 0 {