I can't obtain the answer attribute due to Cannot convert lambda expression to delegate type
. These are my classes and my query :
var file = XDocument.Load("QuestionsTest.xml");
var questions = from answers in file.Root.Elements("Question").Elements("Answers").Elements("Answer")
select new Answer
{
Text = (string)answers,
Correct = (string)answers.Elements("Answer").Single(answer=>(string)answer.Attribute("Correct"))
};
public class Answer
{
public int AnswerID { get; set; }
public string Text { get; set; }
public string Correct { get; set; }
public int Stats { get; set; }
public int QuestionID { get; set; }
}
public class Question
{
public virtual List<Answer> Answers { get; set; }
}
My XML looks like this:
<?xml version="1.0" encoding="utf-8" ?>
<Questions Subject="ADO.NET">
<Question NumberOfAnswers="1">
<Text>Which class should you use to manage multiple tables and relationships among them?</Text>
<Answers>
<Answer>DataRow</Answer>
<Answer>DataView</Answer>
<Answer>DataTable</Answer>
<Answer Correct="Yes">DataSet</Answer>
</Answers>
</Question>
</Questions>
How can I get the answer's attribute?
Enumerable.Single
accepts Func<T,bool>
delegate which should return boolean value. You are passing delegate which returns XAttribute
value. You should compare attribute value with Yes
string to return boolean result:
Single(answer => (string)answer.Attribute("Correct") == "Yes")
This will fix your error. But I think you also should change logic of your query. First change Answer
class, and make Correct
property boolean:
public class Answer
{
public int AnswerID { get; set; }
public string Text { get; set; }
public bool IsCorrect { get; set; }
public int Stats { get; set; }
public int QuestionID { get; set; }
}
And query should look like:
var xdoc = XDocument.Load("QuestionsTest.xml");
var questions =
from q in xdoc.Descendants("Question")
select new Question {
Answers = (from a in q.Descendants("Answer")
select new Answer {
Text = (string)a,
IsCorrect = (string)a.Attribute("Correct") == "Yes"
}).ToList()
};
var questions = from answers in
file.Root.Elements("Question").Elements("Answers").Elements("Answer")
select new Answer
{
Text = (string)answers,
Correct = (string)answers.Attribute("Correct")
};
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