C# LINQ到XML查询不工作

查看以下XML：

<Countries>
   <country name="India">
      <State name="Maharashtra" capital="Mumbai" PIN="400001"/>
      <State Name="Uttar-Pradesh" capital="Lucknow" PIN="220001"/>
   </country>
   <country name="Sri-Lanka">
      <State name="Colombo" capital="Colombo" PIN="123456"/>
      <State name="Candy" capital="Jafana" PIN="654321"/>
   </country>
 </Countries>

其相应的大写和PIN值也应显示在标签中。我怎样才能做到这一点

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提前问候并感谢

您的查询是错误的，您的xml混合了大小写属性。当我在LINQ to XML方面遇到问题时，我会将查询分为多个步骤，以便更轻松地构建所需的查询

以下是您想要的：

// I've changed your xml to be consistent. Lowercase name and captial attributes
string xml = @"<Countries>
                   <country name=""India"">
                       <State name=""Maharashtra"" capital=""Mumbai"" PIN=""400001""/>
                       <State name=""Uttar-Pradesh"" capital=""Lucknow"" PIN=""220001""/>
                   </country>
                   <country name=""Sri-Lanka"">
                       <State name=""Colombo"" capital=""Colombo"" PIN=""123456""/>
                       <State name=""Candy"" capital=""Jafana"" PIN=""654321""/>
                   </country>
               </Countries>";

// Load the xml
XDocument StockDoc = XDocument.Parse(xml);

// Get states where country is "India"
IEnumerable<XElement> states = StockDoc.Root.Descendants("country")
                                       .Where(x => (string)x.Attribute("name") == "India")
                                       .Descendants("State");

// Build a new strongly typed IEnumerable<CountryData> from the xml states.
// Properties on classes in C# typically do not start with underscores. 
IEnumerable<CountryData> countryData = states.Select(y => new CountryData
                                                              {
                                                                  _State = (string)y.Attribute("name").Value,
                                                                  _Capital = (string)y.Attribute("capital").Value,
                                                                  _Pin = (string)y.Attribute("PIN").Value
                                                              });

以查询语法编辑的查询：

var results = from states in StockDoc.Descendants("Countries").Elements("country")
              where (string)states.Attribute("name") == "India"
              select states.Descendants("State")
              .Select(y => new CountryData
                           {
                               _State = (string)y.Attribute("name").Value,
                               _Capital = (string)y.Attribute("capital").Value,
                               _Pin = (string)y.Attribute("PIN").Value
                           });

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请提供错误详细信息“执行时出错”。是指编译错误还是运行时错误？错误消息是怎么说的？这段代码仍然给出了一个运行时错误-“空引用…”“对象引用未设置为对象的实例”。Regard我运行了它，它没有。复制并粘贴我答案中的第一个代码部分。谢谢！！！它运行良好。这是我的错。

// I've changed your xml to be consistent. Lowercase name and captial attributes
string xml = @"<Countries>
                   <country name=""India"">
                       <State name=""Maharashtra"" capital=""Mumbai"" PIN=""400001""/>
                       <State name=""Uttar-Pradesh"" capital=""Lucknow"" PIN=""220001""/>
                   </country>
                   <country name=""Sri-Lanka"">
                       <State name=""Colombo"" capital=""Colombo"" PIN=""123456""/>
                       <State name=""Candy"" capital=""Jafana"" PIN=""654321""/>
                   </country>
               </Countries>";

// Load the xml
XDocument StockDoc = XDocument.Parse(xml);

// Get states where country is "India"
IEnumerable<XElement> states = StockDoc.Root.Descendants("country")
                                       .Where(x => (string)x.Attribute("name") == "India")
                                       .Descendants("State");

// Build a new strongly typed IEnumerable<CountryData> from the xml states.
// Properties on classes in C# typically do not start with underscores. 
IEnumerable<CountryData> countryData = states.Select(y => new CountryData
                                                              {
                                                                  _State = (string)y.Attribute("name").Value,
                                                                  _Capital = (string)y.Attribute("capital").Value,
                                                                  _Pin = (string)y.Attribute("PIN").Value
                                                              });

var results = from States in StockDoc.Descendants("Countries").Descendants("Country")
                  where (string)states.Attribute("Name") == "India"
                  select new CountryData
 {
    _State = (string)States.Element("Country").Element("State").Attribute("Name").Value,
    _Capital = (string)States.Element("Country").Element("State").Attribute("Capital").Value,
    _Pin= (string)States.Element("Country").Element("State").Attribute("PIN").Value
 };

var results = from states in StockDoc.Descendants("Countries").Elements("country")
              where (string)states.Attribute("name") == "India"
              select states.Descendants("State")
              .Select(y => new CountryData
                           {
                               _State = (string)y.Attribute("name").Value,
                               _Capital = (string)y.Attribute("capital").Value,
                               _Pin = (string)y.Attribute("PIN").Value
                           });