1.
查询接口：建议使用IEnumerable
更新、创建接口：不要使用IEnumerable（maybe 接口会重复调用）；建议使用可以讲结果保存到内存中的类型（like：IList、IDictionary）
var result = _serviceItemConsumeRecordSvc.Add(consumeResult).ToList();
//if _serviceItemConsumeRecordSvc.Add return as IEnumerable<object>
//warn,first call Add():result.Any()
if (result == null || !result.Any())
{
var msg = $"no serviceItemConsumeRecord can be added";
_loger.Warn(msg, consumeResult );
yield return new SPOSpendingActionResponseItem()
{
Sucess = false,
Message = msg
};
continue;
}
#endregion
#region return
//warn,second call Add(): foreach (var itemResult in result)
foreach (var itemResult in result)
{
//……
}
#endregion
2.
foreach 循环中 yield return 之后，记得添加：continue
非 foreach 循环中 ：返回 yield break;（yield return null之后，后续代码仍旧会执行）
public IEnumerable<SPOUsedSearchExtendResponseItem> UsedRecordFullSearch(SPOUsedSearchExtendRequest req)
{
var usedRecords = UsedRecordsSearch(req);
if (usedRecords == null || usedRecords.Data == null || !usedRecords.Data.Any())
{
//warn ：use "yield break" instead of "yield return null"(;
//otherwise [ var consumerRecordLK = usedRecords.Data.ToLookup(_ => _.ProduceRecordNumber);] will execute
yield break;
}
var consumerRecordLK = usedRecords.Data.ToLookup(_ => _.ProduceRecordNumber);
//……
}
#region return
foreach (var itemResult in result)
{
if (!itemResult.IfSuccess || itemResult.SICRs == null || !itemResult.SICRs.Any())
{
yield return new SPOSpendingActionResponseItem()
{
Sucess = itemResult.IfSuccess,
SICR = itemResult.SICRs!=null? itemResult.SICRs.ToList():null,
Message = itemResult.Message
};
// warn：
// if： in foreach， yield return & not end continue
// then：【 var produceRecordNumbers = itemResult.SICRs.Select(_ => _.ProduceRecordNumber); 】will execute，instead of skip to foreach
continue;
}
var produceRecordNumbers = itemResult.SICRs.Select(_ => _.ProduceRecordNumber);
//……
}
#endregion
原文：https://www.cnblogs.com/panpanwelcome/p/14673083.html