C＃获取XML节点值

Question

I want to get the question and answer values using C#, but before that I want to get the ID I need. I'm using this XML:

<root>
  <information>
    <name>Tasks</name>
    <date>15-05-2005</date>
  </information>
  <tasks>
      <task>
        <id>1</id>
        <question>Here comes question 1</question>
        <answer>Answer 1</answer>
      </task>
      <task>
        <id>2</id>
        <question>Here comes question 2</question>
        <answer>Answer 2</answer>
      </task>
      <task>
        <id>3</id>
        <question>Here comes question 3</question>
        <answer>Answer 3</answer>
      </task>
</root>

C# code:

XDocument tasks;
int TheIdINeed = 2;
string quest = "";
string answ = "";

On form load:

tasks = XDocument.Load(leveltoload);
var status = tasks.Element("level").Element("information");
quest = tasks.Element("root").Element("tasks").Element("task").Element("question").Value; // It returns me the first task data, but I need to load data with required Id (int TheIdINeed = ...)

I'm sorry, my English isn't good.

Answer 1

You could use this

string id = "2";
var qa = doc.Descendants("tasks").Elements("task")
                       .Where(x => x.Element("id").Value == id).FirstOrDefault();
if (qa != null)
{
   var question = qa.Element("question").Value;
   var answer = qa.Element("answer").Value;
}

If you need to get the question and answers outside of this scope, I suggest creating a class that will hold the data. For example,

public class QuestionAnswer
{
    public string ID { get; set; }
    public string Question { get; set; }
    public string Answer { get; set; }
}


var qa = doc.Descendants("tasks").Elements("task")
            .Where(x => x.Element("id").Value == id)
            .Select(x => new QuestionAnswer() 
                    {
                      ID = "2",
                      Question = x.Element("question").Value,
                      Answer = x.Element("answer").Value
                    });

You could improve the above by using a Dictionary to store the Question/Answer pair but it's just an example to give you an idea. in case your QuestionAnswer class is more complicated than just those two properties.

Answer 2

var empty = new XElement("e");
var sID = id.ToString();
var element = tasks.Descendants("task")
                   .FirstOrDefault(x => ((string)x.Element("id")) == sID);
string quest = (string)((element ?? empty).Element("question"));
string answ = (string)((element ?? empty).Element("answer"));

Answer 3

you can get all data to dictionary so you won't repeat conversion to string

var res = tasks.Descendants("task")
    .Select(x => x.Elements().ToDictionary(e => e.Name.ToString(), e => (string)e.Value))
    .FirstOrDefault(x => x["id"] == id);

res["question"]
res["answer"]

but if there tasks without questions or answers in your xml you have to check if res is contains key before you will get value, or use TryGetValue:

string question;
res.TryGetValue("question", out question);