Parsing XML with Linq with multiple descendants

问题

I have a probleme to parse multiple XML field

This a the style of the XML :

<students>
  <student>
    <student_id>1</student_id>
    <student_name>Mike</student_name>
    <subjects>
      <subject>
        <school_subject>History</school_subject>
      </subject>
      <subject>
        <school_subject>Maths</school_subject>
      </subject>
      <subject>
        <school_subject>English</school_subject>
      </subject>
    </subjects>
  </student>
  <student>
    ...
  </student>
</students>

I can parse it for the simple field like student_id and student_name but when there are multiple repetition of a same field I don't know how to do :/ This is my source code of the parsing.

I made two classes :

• Subject containing the name of the school subject
• student containing id and name and a list of class Subject.

Now the source code :

List<Student> L1 = new List<Student>();

XDocument doc = XDocument.Load(s);
var q = from b in doc.Descendants("student")
select new
{
    s_id = (string)b.Element("student_id"),
    s_name = (string)b.Element("student_name"),
    s_subject = (Subject)b.Elements("school_subject")
};
foreach (var p in q)
{
    L1.Add(new Student() { id = p.s_id, name = p.s_name, subject = p.s_subject });
}
listBox1.ItemsSource = L1;

Thanks for reading and sorry for my very bad english.

回答1:

According to your xml student can have several subjects. So, you need collection of subjects as property of student:

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public List<Subject> Subjects { get; set; }
}

public class Subject
{
    public string Name { get; set; }
}

And here is parsing. To fill get student's subjects you need to do sub query:

XDocument xdoc = XDocument.Load(s);
IEnumerable<Student> students =
    from s in xdoc.Descendants("student")
    select new Student()
    {
        Id = (int)s.Element("student_id"), // you can cast to int
        Name = (string)s.Element("student_name"),
        Subjects = s.Element("subjects") // here goes sub query
                    .Elements("subject")
                    .Select(subj => new Subject() { 
                       Name = (string)subj.Element("school_subject") 
                    }).ToList()
    };

BTW I think you can use simple string to hold subject name - you don't really need class for that.

回答2:

since you have multiple subjects in xml s_subject should be a list of Subject

doc.Elements("Student").Select(
x=>
    s_id = (string)x.Element("student_id"),
    s_name = (string)x.Element("student_name"),
    s_subject = x.Element("subjects").Elements("subject")
                 .Select(s=>s.Element("school_subject").Value)
                 .ToList<Subject>()
);

来源：https://stackoverflow.com/questions/13904414/parsing-xml-with-linq-with-multiple-descendants