.NET XDocument 处理问题答案

【问题标题】：.NET XDocument processing issue.NET XDocument 处理问题
【发布时间】：2018-08-28 12:49:50
【问题描述】：

我有以下 XML，我正在尝试获取等于 974 的“MarcEntryInfo”元素值，有人知道这是如何使用 XDocument 表达的吗？

在我的 C# 代码中，我尝试获取该值，但似乎无法检索该值。

另一种表达我要问的方式是，如果 MarcEntryInfo 的子标签具有特定值的 entryID，则返回该特定 MarcEntryInfo 的文本子元素的字符串值。

谢谢

<LookupTitleInfoResponse xmlns="http://schemas.sirsidynix.com/symws/standard">
  <TitleInfo>
    <titleID>4971729</titleID>
    <CallInfo>
      <libraryID>PRODUCT</libraryID>
      <classificationID>ALPHANUM</classificationID>
      <callNumber>WS6689</callNumber>
      <numberOfCopies>1</numberOfCopies>
      <ItemInfo>
        <itemID>4971729-1001</itemID>
        <itemTypeID>TAPE</itemTypeID>
        <currentLocationID>STORE</currentLocationID>
        <homeLocationID>STORE</homeLocationID>
        <chargeable>true</chargeable>
        <fixedTimeBooking>false</fixedTimeBooking>
      </ItemInfo>
    </CallInfo>
    <BibliographicInfo>
      <MarcEntryInfo>
        <label>MD-ARK</label>
        <entryID>974</entryID>
        <indicators></indicators>
        <text>ark:/81055/vdc_100000006155.0x2afcee</text>
        <entryTypeCodes>L</entryTypeCodes>
      </MarcEntryInfo>
      <MarcEntryInfo>
        <label>L-ARK: INGESTED</label>
        <entryID>975</entryID>
        <indicators></indicators>
        <text>ark:/81055/vdc_100055625567.0x000002</text>
        <entryTypeCodes>L</entryTypeCodes>
      </MarcEntryInfo>
      <MarcEntryInfo>
        <label>SHELFMARK</label>
        <entryID>087</entryID>
        <indicators></indicators>
        <text>WS6689</text>
        <entryTypeCodes>VR</entryTypeCodes>
      </MarcEntryInfo>
      <MarcEntryInfo>
        <label>Unpublished series</label>
        <entryID>441</entryID>
        <indicators></indicators>
        <text>Wildlife species reels</text>
        <entryTypeCodes>MTR</entryTypeCodes>
      </MarcEntryInfo>
      <MarcEntryInfo>
        <label>Other ref. no.</label>
        <entryID>091</entryID>
        <indicators></indicators>
        <text>W Melanogrammus aeglefinus r1</text>
      </MarcEntryInfo>
      <MarcEntryInfo>
        <label>Product title</label>
        <entryID>499</entryID>
        <indicators></indicators>
        <text>Melanogrammus aeglefinus r1</text>
        <entryTypeCodes>MAR</entryTypeCodes>
      </MarcEntryInfo>
      <MarcEntryInfo>
        <label>Format</label>
        <entryID>310</entryID>
        <indicators></indicators>
        <text>1 tape reel</text>
      </MarcEntryInfo>
      <MarcEntryInfo>
        <label>Cataloguing status</label>
        <entryID>971</entryID>
        <indicators></indicators>
        <text>prc</text>
      </MarcEntryInfo>
      <MarcEntryInfo>
        <label>Data source</label>
        <entryID>976</entryID>
        <indicators></indicators>
        <text>WSF</text>
      </MarcEntryInfo>
      <MarcEntryInfo>
        <label>Content  code</label>
        <entryID>312</entryID>
        <indicators></indicators>
        <text>a</text>
        <entryTypeCodes>L</entryTypeCodes>
      </MarcEntryInfo>
    </BibliographicInfo>
  </TitleInfo>
</LookupTitleInfoResponse>

【问题讨论】：

标签： c# .net xml linq linq-to-xml

【解决方案1】：

为了简洁起见，我截断了 XML。需要注意的几点：

您需要声明命名空间才能找到您的元素
您需要在 XPath 表达式中按命名空间引用元素
您应该选择具有目标值的entryID 元素并向上导航到其父元素

示例代码如下。一旦你有了entryInfo 元素，你就可以从它的子元素中提取你需要的任何信息。

void Main()
{
    var xml = @"<LookupTitleInfoResponse xmlns=""http://schemas.sirsidynix.com/symws/standard"">
      <TitleInfo>
        <titleID>4971729</titleID>
        <CallInfo>
          <libraryID>PRODUCT</libraryID>
          <classificationID>ALPHANUM</classificationID>
          <callNumber>WS6689</callNumber>
          <numberOfCopies>1</numberOfCopies>
          <ItemInfo>
            <itemID>4971729-1001</itemID>
            <itemTypeID>TAPE</itemTypeID>
            <currentLocationID>STORE</currentLocationID>
            <homeLocationID>STORE</homeLocationID>
            <chargeable>true</chargeable>
            <fixedTimeBooking>false</fixedTimeBooking>
          </ItemInfo>
        </CallInfo>
        <BibliographicInfo>
          <MarcEntryInfo>
            <label>MD-ARK</label>
            <entryID>974</entryID>
            <indicators></indicators>
            <text>ark:/81055/vdc_100000006155.0x2afcee</text>
            <entryTypeCodes>L</entryTypeCodes>
          </MarcEntryInfo>
          <MarcEntryInfo>
            <label>Content  code</label>
            <entryID>312</entryID>
            <indicators></indicators>
            <text>a</text>
            <entryTypeCodes>L</entryTypeCodes>
          </MarcEntryInfo>
        </BibliographicInfo>
      </TitleInfo>
    </LookupTitleInfoResponse>";

    var nsManager = new XmlNamespaceManager(new NameTable());
    nsManager.AddNamespace("ns", "http://schemas.sirsidynix.com/symws/standard");

    var doc = XDocument.Parse(xml);
    var entryInfo = doc.XPathSelectElement("//ns:entryID[contains(text(), '974')]/..", nsManager);
    Console.WriteLine(entryInfo);

    // Output:
    // <MarcEntryInfo xmlns="http://schemas.sirsidynix.com/symws/standard">
    //   <label>MD-ARK</label>
    //   <entryID>974</entryID>
    //   <indicators></indicators>
    //   <text>ark:/81055/vdc_100000006155.0x2afcee</text>
    //   <entryTypeCodes>L</entryTypeCodes>
    // </MarcEntryInfo>
}

【讨论】：

【解决方案2】：

我认为你可以在这里使用 Linq to XML

下面的代码将让您获取 XML 上的所有条目 Id 标记

如果您需要特定值，可以添加 .SingleOrDefault(el=>el.Value=="974");

var xml = XElement.Load(YourDocumentPath);

var allEntryIds = xml.Elements()
    .SingleOrDefault(el=>el.Name.LocalName=="TitleInfo")
    .Elements()
        .SingleOrDefault(el => el.Name.LocalName == "BibliographicInfo")
        .Elements()
            .Where(el => el.Name.LocalName == "MarcEntryInfo")
            .Elements()
                .Where(el => el.Name.LocalName == "entryID");

【讨论】：