About the SQLMapper addTypeHandler exception

` public class JsonConvertHandler : SqlMapper.TypeHandler
{
public override T Parse(object value)
{
return JsonConvert.DeserializeObject((string)value);
}

    public override void SetValue(IDbDataParameter parameter, T value)
    {
        parameter.Value = JsonConvert.SerializeObject(value);
    }
}`

StringBuilder strSql = new StringBuilder(); strSql.Append("select ruleid, websetting, createtime, rulename, userid, offstarttime, offendtime, replacestr, payrate, paymodel, limitsetting ,isuse "); strSql.Append(" from TB_U_UserPay_Rule "); strSql.Append(" where ruleid=@ruleid"); SqlMapper.AddTypeHandler(new JsonConvertHandler<UserPay_Rule_LimitModel>()); SqlMapper.AddTypeHandler(new JsonConvertHandler<UserPay_Rule_WebModel>()); return DapperHelper.QuerySingleOrDefault<TB_U_UserPay_RuleModel>(strSql.ToString(), new { ruleid });

System.Data.DataException: Error parsing column 1 (websetting={"iswebshow":1,"moneytype":1,"showminmoney":0.0,"logo":null,"sevicelink":null,"gamesitelink":null,"notice":null} - String) ---> System.InvalidCastException: 从“System.String”到“GamePal.Model.UserPay.UserPay_Rule_WebModel”的强制转换无效

It is not certain why this anomaly occurs, but it is most likely to occur after the hot update site,After the application pool is reclaimed, the exception disappears

I'm now trying to do this when the application starts up, but that remains to be seen
protected void Application_Start() { SqlMapper.ResetTypeHandlers(); }

Start with the reported SqlMapper.AddTypeHandler calls and the Application_Start ResetTypeHandlers call, then trace the QuerySingleOrDefault path that parses websetting. Reproduce the hot-update or application-pool-recycle condition described in the report. Done means the cause of the invalid cast is identified and a verified resolution or clear limitation is documented.