读取和检索xml元素

本文关键字：元素 xml 检索 读取 | 更新日期: 2023-09-27 18:28:20

我需要读取xml文件中的所有嵌套元素。下面是程序。在下面的程序中，我可以获得Question and Answer的值，但不能获得SubQuestionAnswer/Question和SubQuestion-Answer/Answer。有人能告诉我程序出了什么问题吗

XmlDocument xmlDocument = new XmlDocument();
            var fataQuestionnaire = @"<?xml version=""1.0"" encoding=""UTF-16""?>
                <FatcaQuestionnaire xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema"">
                  <QuestionAnswers>
                    <QuestionAnswer>
                      <Question>What is your source of wealth?</Question>
                      <Answer>I am italian </Answer>
                    </QuestionAnswer>
                    <QuestionAnswer>
                      <Question>What is your occupation and name of employer?</Question>
                      <Answer>Bestinvest</Answer>
                    </QuestionAnswer>
                    <QuestionAnswer>
                      <Question>Do you have a business or residence in?</Question>
                      <Answer>Yes</Answer>
                    </QuestionAnswer>
                    <QuestionAnswer>
                      <Question>How long have you lived outside of Albania</Question>
                      <Answer>5 years</Answer>
                    </QuestionAnswer>
                    <QuestionAnswer>
                      <Question>Do you return to Albania on a regular basis</Question>
                      <Answer>Yes</Answer>
                      <SubQuestionAnswer>
                        <Question>How frequently?</Question>
                        <Answer>every year</Answer>
                      </SubQuestionAnswer>
                    </QuestionAnswer>
                    <QuestionAnswer>
                      <Question>Do you have family in Albania?</Question>
                      <Answer>Yes</Answer>
                      <SubQuestionAnswer>
                        <Question>Family relationship?</Question>
                        <Answer>My parents lives there</Answer>
                      </SubQuestionAnswer>
                    </QuestionAnswer>
                    <QuestionAnswer>
                      <Question>Are you connected to the government of Albania?</Question>
                      <Answer>Yes</Answer>
                      <SubQuestionAnswer>
                        <Question>Nature of association</Question>
                        <Answer>I was an ex minister</Answer>
                      </SubQuestionAnswer>
                    </QuestionAnswer>
                    <QuestionAnswer>
                      <Question>Do you send or receive money from Albania?</Question>
                      <Answer>Yes</Answer>
                      <SubQuestionAnswer>
                        <Question>How often and why?</Question>
                        <Answer>Every month for my parents to live with.</Answer>
                      </SubQuestionAnswer>
                    </QuestionAnswer>
                  </QuestionAnswers>
                </FatcaQuestionnaire>";
            XmlTextReader reader = new XmlTextReader(new StringReader(fataQuestionnaire));

            xmlDocument.Load(reader);
            XmlElement xmlRoot = xmlDocument.DocumentElement;
            if (xmlRoot != null)
            {
                XmlNodeList xnlNodes = xmlRoot.SelectNodes("/FatcaQuestionnaire/QuestionAnswers/QuestionAnswer");
                string questionanswer =string.Empty;

                if (xnlNodes != null)
                    foreach (XmlNode xndNode in xnlNodes)
                    {
                        if (xndNode["Question"] != null)
                            questionanswer = (xndNode["Question"].InnerText);
                        if (xndNode["Answer"] != null)
                            questionanswer = (xndNode["Answer"].InnerText);

                        if (xndNode["SubQuestionAnswer/Question"] != null)
                            questionanswer = (xndNode["SubQuestionAnswer/Question"].InnerText);
                        if (xndNode["SubQuestionAnswer/Answer"] != null)
                            questionanswer = (xndNode["SubQuestionAnswer/Answer"].InnerText);
                    }

            }

读取和检索xml元素

XPath语法不受索引器支持。你可以这样修复：

if (xndNode["SubQuestionAnswer"] != null)
{
    if (xndNode["SubQuestionAnswer"]["Question"] != null)
        questionanswer = (xndNode["SubQuestionAnswer"]["Question"].InnerText);
    if (xndNode["SubQuestionAnswer"]["Answer"] != null)
        questionanswer = (xndNode["SubQuestionAnswer"]["Answer"].InnerText);
}

另一个选项：使用XDocument和Linq代替XmlDocument。

加载xml:

XDocument doc = XDocument.Parse(fataQuestionnaire);

示例用法：

List<KeyValuePair<string,string>> allQuestionAnswers = doc.Descendants("QuestionAnswer").Union(doc.Descendants("SubQuestionAnswer"))
    .Select(qa=>new KeyValuePair<string,string>(qa.Element("Question").Value, qa.Element("Answer").Value)).ToList();
foreach (var pair in allQuestionAnswers)
{
    Console.WriteLine("Q: " + pair.Key +"'nA: " + pair.Value + "'n");
}

结果：

Q: What is your occupation and name of employer?
A: Bestinvest
Q: Do you have a business or residence in?
A: Yes
Q: How long have you lived outside of Albania
A: 5 years
Q: Do you return to Albania on a regular basis
A: Yes
Q: Do you have family in Albania?
A: Yes
Q: Are you connected to the government of Albania?
A: Yes
Q: Do you send or receive money from Albania?
A: Yes
Q: How frequently?
A: every year
Q: Family relationship?
A: My parents lives there
Q: Nature of association
A: I was an ex minister
Q: How often and why?
A: Every month for my parents to live with.

或：

doc.Descendants("QuestionAnswer").ToList().ForEach(qa =>
{
    Console.WriteLine("Q: " + qa.Element("Question").Value + "'nA: " + qa.Element("Answer").Value);
    var sqa = qa.Element("SubQuestionAnswer");
    if (sqa != null)
    {
        Console.WriteLine("'tQ: " + sqa.Element("Question").Value + "'n'tA: " + sqa.Element("Answer").Value);
    }
    Console.WriteLine();
 });

结果：

Q: What is your source of wealth?
A: I am italian 
Q: What is your occupation and name of employer?
A: Bestinvest
Q: Do you have a business or residence in?
A: Yes
Q: How long have you lived outside of Albania
A: 5 years
Q: Do you return to Albania on a regular basis
A: Yes
    Q: How frequently?
    A: every year
Q: Do you have family in Albania?
A: Yes
    Q: Family relationship?
    A: My parents lives there
Q: Are you connected to the government of Albania?
A: Yes
    Q: Nature of association
    A: I was an ex minister
Q: Do you send or receive money from Albania?
A: Yes
    Q: How often and why?
    A: Every month for my parents to live with.
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