c# - 为什么这个指定的转换无效？？

Question

我使用以下代码将数据从 sql 阅读器映射到 C# 对象。 Power 在代码和 sql 数据库中都是 float 据类型.. y 是否出现了转换错误消息？

private Entity.PanelDetail MapDataReader(SqlDataReader dataReader)
    {
        Entity.PanelDetail panelDetail = new Entity.PanelDetail();
        panelDetail.IdPanelDetail = DataReaderExtensions.GetStringOrNull(dataReader, "idPanelDetail");
        panelDetail.IdDeviceDetail = DataReaderExtensions.GetStringOrNull(dataReader, "idDeviceDetail");
        panelDetail.Power = DataReaderExtensions.GetFloatOrNull(dataReader, "Power");
        panelDetail.Current = DataReaderExtensions.GetFloatOrNull(dataReader, "Current");
        panelDetail.Length = DataReaderExtensions.GetFloatOrNull(dataReader, "Length");
        panelDetail.Width = DataReaderExtensions.GetFloatOrNull(dataReader, "Width");
        panelDetail.CreatedBy = DataReaderExtensions.GetStringOrNull(dataReader, "CreatedBy");
        panelDetail.CreationDate = DataReaderExtensions.GetDateTimeOrNull(dataReader, "CreationDate");
        panelDetail.ModifiedBy = DataReaderExtensions.GetStringOrNull(dataReader, "ModifiedBy");
        panelDetail.ModifiedDate = DataReaderExtensions.GetDateTimeOrNull(dataReader, "ModifiedDate");
        panelDetail.IsActive = DataReaderExtensions.GetBoolOrNull(dataReader, "IsActive");
        panelDetail.IsDeleted = DataReaderExtensions.GetBoolOrNull(dataReader, "IsDeleted");

        return panelDetail;
    }

Answer 1

我的猜测是该值作为装箱的 double 而不是 float 返回。尝试使用

 (float) dataReader.GetDouble(fieldOrdinal);

参见 Mapping CLR Parameter Data