public T GetByKey <T>(object keyValue)
where T : new()
{
//断言参入的参数为null或者空字符串（RErrorCode.ArgmentesError - 0x00000014）
PreconditionAssert.IsNotNull(keyValue, ErrorMessages.NullReferenceException);
PreconditionAssert.IsNotNullOrEmpty(keyValue.ToString(), ErrorMessages.NullReferenceException);
ORMHelper.EntityIsMappingDatabase(typeof(T), ErrorMessages.EntityMappingError);
try
{
SelectCommandCreator dbCommandCreator = new SelectCommandCreator(dbAccess);
dbCommandCreator.ObjectType = typeof(T);
dbCommandCreator.KeyValue = keyValue;
dbCommandCreator.SelectType = SelectType.GetOneByKeyValue;
DbCommand dbCommand = dbCommandCreator.GetDbCommand();
DataTable dt = dbAccess.GetDataTableByCommand(dbCommand);
if (dt.Rows.Count == 0)
{
return(default(T));
}
else if (dt.Rows.Count == 1)
{
return(ORMHelper.ConvertDataRowToEntity <T>(dt.Rows[0]));
}
else
{
//引发数据获取结果错误
throw new ORMException(ErrorMessages.ResultNotUniqueMessage);
}
}
catch (Exception ex)
{
//其他未处理的异常
throw new ORMException("Get object by key error - " + keyValue, ex);
}
}