Question

I am not so far good in linq so was trying to write Linq query to check whether child topic node exist if code=”111″ && isDisplay=”Y” or not.i am using .Any condition in Second method but still i am not sure about this.

static void Main(string[] args)
{
    XElement rootElement = XElement.Load("TestXML.xml");
    int StyCode = 1;
    var lv1s = from lv1 in rootElement.Descendants("Class")
               where lv1.Attribute("Code").Value.Equals("001")
               select (from ltd in lv1.Descendants("Subject")
                       where ltd.Attribute("Course").Value.Equals("Engish")
                       select GetChildFromSubject(StyCode, ltd)).FirstOrDefault();

       }

private static bool GetChildFromSubject(int styCode, XElement subject)
{
    if (styCode == 0)
        return subject.Attribute("SpeciaGuest").Value.Equals("Y");
    else
    {
        //Below is the main issue with and condition on attributes.
        return subject.Attribute("AllTeachers").Value.Equals("Y") ||
               subject.Elements("Topic").Attributes("Code")
               .Any(x => x.Value.Equals("111")) &&       subject.Elements("Topic").Attributes("isDisplay")
                        .Any(y => y.Value.Equals("Y"));
    }
}

Below is XML file

<Class Code="002">
    <Subject Course="Math" AllTeachers='Y' SpeciaGuest='N'>
      <Topic Code="1" isDisplay="Y">LAW1</Topic>
      <Topic Code="2" isDisplay="Y">
        LAW2
      </Topic>
      <Topic Code="3" isDisplay="N">
        LAW3
      </Topic>
    </Subject>
    <Subject Course="Engish" AllTeachers='N' SpeciaGuest='Y'>
      <Topic Code="111" isDisplay="Y">LAW1</Topic>
    </Subject>
    <Subject Course="History" AllTeachers='Y' SpeciaGuest='Y'></Subject>
  </Class>

Answer 1

Per your comment:

Magnum : i want to check topic node exist if code=”111″ && isDisplay=”Y”

If you’re trying to return the TOPIC node if code=111 and isDiaply=Y, then here is the LINQ query in one shot:

List<XElement> subjects = template.Descendants("Subject")
            .Elements("Topic")
                .Where(elementNode => elementNode.Attribute("Code").Value == "111" && elementNode.Attribute("isDisplay").Value == "Y").ToList();