c# 如何在不满足条件时显示错误 - 对于每个语句

Question

我有代码（有效），它将遍历一系列 XML 元素 (Id)，当它找到元素值与预定义变量 (cpluuid) 之间的匹配项时，它将根据预定义函数 (SetNewValue) 更新另一个子元素值 (OriginalFileName)。

我想不通的是如何抛出错误，只有如果它循环遍历了所有个元素，但未找到匹配项。理想情况下，它还会停止执行我程序中的其余代码。

我可以让它在找到每个不匹配的元素时抛出错误，但这不是我想要的。

XML 样本：

<PackingList xmlns="http://www.smpte-ra.org/schemas/2067-2/2016/PKL">
  <Id>urn:uuid:296a656c-3610-4de1-9b08-2aa63245788d</Id>
  <AnnotationText>IMF_JOT_Sample</AnnotationText>
  <IssueDate>2018-02-16T20:59:42-00:00</IssueDate>
  <Issuer>Generic</Issuer>
  <Creator>Generic</Creator>
  <AssetList>
    <Asset>
      <Id>urn:uuid:dd5a88d2-ccec-4b22-8584-fda51945c3ea</Id>
      <AnnotationText>Audio_dd5a88d2-ccec-4b22-8584-fda51945c3ea.mxf</AnnotationText>
      <Hash>OwjRFnWZCdKHSZ+3PBXroDhMMlY=</Hash>
      <Size>1458414</Size>
      <Type>application/mxf</Type>
      <OriginalFileName>Audio_dd5a88d2-ccec-4b22-8584-fda51945c3ea.mxf</OriginalFileName>
      <HashAlgorithm Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
    </Asset>
    <Asset>
      <Id>urn:uuid:9e11458a-71fb-4702-8609-55d2308dcc64</Id>
      <AnnotationText>Sub_9e11458a-71fb-4702-8609-55d2308dcc64.mxf</AnnotationText>
      <Hash>48KyxgwCJVXIdgAGfaNApheQN5M=</Hash>
      <Size>34509</Size>
      <Type>application/mxf</Type>
      <OriginalFileName>Sub_9e11458a-71fb-4702-8609-55d2308dcc64.mxf</OriginalFileName>
      <HashAlgorithm Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
    </Asset>
      <Asset>
      <Id>urn:uuid:d0686356-19c7-4bf4-b915-db778c308d1</Id>
      <AnnotationText>CPL_IMF_JOT_Sample.xml</AnnotationText>
      <Hash>5Yf4BV4GZ4qE9EjvtohZ8Rq8M2w=</Hash>
      <Size>21881</Size>
      <Type>text/xml</Type>
      <OriginalFileName>CPL_IMF_JOT_Sample_272.xml</OriginalFileName>
      <HashAlgorithm Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
    </Asset>
    <Asset>
      <Id>urn:uuid:3f57f474-4c81-438e-a67d-1b08fa09a10d</Id>
      <AnnotationText>IMF_JOT_Sample</AnnotationText>
      <Hash>q8TiPkg/3devlN3LXnBhrgkZ968=</Hash>
      <Size>713</Size>
      <Type>text/xml</Type>
      <OriginalFileName>OPL_3f57f474-4c81-438e-a67d-1b08fa09a10d.xml</OriginalFileName>
      <HashAlgorithm Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
    </Asset>
  </AssetList>
</PackingList>

代码：

foreach (var pklasset in pklassetElements)
{
    var idElement = pklasset.Descendants(pklns + "Id").First();
    if (!idElement.Value.Equals(cpluuid))
        continue;

    SetNewValue(pklasset, pklns + "OriginalFileName", outfile);//update cpl filename in pkl

}

Answer 1

一种方法是设置一个 bool 标志变量来跟踪您是否找到匹配项：

bool foundItem = false;

foreach (var pklasset in pklassetElements)
{
    var idElement = pklasset.Descendants(pklns + "Id").First();
    if (!idElement.Value.Equals(cpluuid)) continue;

    //update cpl filename in pkl
    SetNewValue(pklasset, pklns + "OriginalFileName", outfile);
    foundItem = true;
    break;
}

if (!foundItem) throw new Exception("Item not found");

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