Question

我一直在阅读msdn和其他一些教程中的linq to xml文档但是我现在找不到正确的方法来执行此查询：（

基本上，我想循环通过课堂上的每个学生，对于每个问题，保持个人技能的计数器，即对于学生123，计数应该是001.101.033.002.001 - 1,001.101.035.002.001 - 1,001.101.033.002.002 - 0.因为技能计数器是基于问题是正确的（1）还是错误的（0）。

<assessment name="english101" level="primary 6">
   <class id="23" name="1A">
      <student id="123" name="Jack Black">
         <question id="101" correct="1">
            <skill id="001.101.033.002.001" topicId="033" subtopicId="002" subtopicdesc="Launching a browser" topicdesc="Point and Click">Able to recognize and use desktop icon</skill>

            <skill id="001.101.035.002.001" topicId="035" topicDesc="Typing" subtopicId="002" subtopicDesc="Using Words">Able to write on screen</skill>
         </question>

         <question id="102" correct="0">
            <skill id="001.101.033.002.002" topicId="033" subtopicId="002" subtopicdesc="Launching a browser" topicdesc="Point and Click">Able to recognize and use the mouse</skill>

            <skill id="001.101.035.002.001" topicId="035" topicDesc="Typing" subtopicId="002" subtopicDesc="Using Words">Able to write on screen</skill>
         </question>
      </student>

      <student id="124" name="Tim Robbins">
         <question id="103" correct="1">
            <skill id="001.101.033.002.002" topicId="033" subtopicId="002" subtopicdesc="Launching a browser" topicdesc="Point and Click">Able to recognize and use the mouse</skill>

            <skill id="001.101.035.002.001" topicId="035" topicDesc="Typing" subtopicId="002" subtopicDesc="Using Words">Able to write on screen</skill>
         </question>

         <dtasResult>
            <skill id="001.101.033.002.002" result="weak" />

            <skill id="001.101.033.002.002" result="strong" />
         </dtasResult>
      </student>
   </class>
</assessment>

到目前为止我的代码在这里：

    //Open up the xml and traverse to the student nodes.
                    XElement root = XElement.Load(fileLocation);
                    IEnumerable<XElement> students = root.Elements("class").Elements("student");

                    string currentStudentId = "";
                    foreach (XElement student in students)
                    {
                        currentStudentId = student.Attribute("id").ToString();
                        //this code chunk below doesn't work!
XElement questions = root.Descendants("question")
                                                .Where(question =>
                                                question.Attribute(""));

                        Console.WriteLine(student.DescendantsAndSelf("question"));
                        Console.WriteLine();
                        Console.WriteLine();
                    }

我还没有弄清楚如何为每个学生的每个问题做一个循环..而且在foraech中间的代码不起作用!!

更新

如果我想计算每个学生的总问题，我怎样才能修改上面的查询呢？我尝试grp.Count（z =＆gt; z.Correct）和其他方法，但我无法做到这一点，谢谢：）

Answer 1

第二次编辑评论;我认为这可以做你想要的......

var qry = from cls in doc.Root.Elements("class")
          from student in cls.Elements("student")
          from question in student.Elements("question")
          from skill in question.Elements("skill")
          select new {
            Student = (int)student.Attribute("id"),
            Skill = (string)skill.Attribute("id"),
            Correct = (int)question.Attribute("correct")
          } into denorm
          group denorm by new {
            denorm.Student,
            denorm.Skill
          } into grp
          orderby grp.Key.Student, grp.Key.Skill
          select new {
            grp.Key.Student,
            grp.Key.Skill,
            Tally = grp.Sum(x => x.Correct)
          };

foreach (var row in qry)
{
  Console.WriteLine("{0}\t{1}\t{2}",
    row.Student, row.Skill, row.Tally);
}

Answer 2

不确定这是否是您想要的，但我会试一试：

foreach (XElement student in students)
        {
            currentStudentId = student.Attribute("id").ToString();
            Console.WriteLine(currentStudentId);
            //this code chunk below doesn't work!
            IEnumerable<XElement> correctQuestions = student.Descendants("question").
                                  Where(q => q.Attribute("correct").Value == "1");                
            //Here you would do same for false answers

            //loop through correct answers
            foreach (XElement q in correctQuestions)
            {
                IEnumerable<XElement> skills = q.Descendants("skill");
                foreach (XElement s in skills)
                {
                    //this prints "001.101.035.002.001" etc  
                    Console.WriteLine(s.Attribute("id").Value);
                }
            }
            Console.WriteLine();
        }

如何在linq中将此xml数据的查询写入xml？

更新

2 个答案: