public void Test1([DataSources] string context) { Query.ClearCaches(); var ms = new MappingSchema(); ms.SetConvertExpression <string?, CustomFieldType?>(s => CustomFieldType.FromString(s)); ms.SetConvertExpression <CustomFieldType, DataParameter>(_ => new DataParameter(null, _ != null ? _.ToString() : null), false); using (var db = GetDataContext(context, ms)) using (var tbl = db.CreateLocalTable <Issue1363Record>()) { db.Insert(new Issue1363CustomRecord2() { Id = 1 }); db.Insert(new Issue1363CustomRecord2() { Id = 2, Field1 = new CustomFieldType() }); db.Insert(new Issue1363CustomRecord2() { Id = 3, Field1 = new CustomFieldType() { Field1 = "test" } }); Assert(db); } }