Question

I am using following linq query to work with XML file..

XElement rootElement = XElement.Load(@"test.xml"); 
int StyCode; 
var lv1s = from lv1 in rootElement.Descendants("Class") 
where lv1.Attribute("Code").Value.Equals("002") 
select new 
{ 
Children = from ltd in lv1.Descendants("Subject") 
where ltd.Attribute("Course").Value.Equals("Math") 
select new 
{ 

****//In This below section need result on condition based... ****
if(StyCode=0)  
{
Children1 = ltd.Attribute("AllTeachers").Value.Equals("Y") ? true : false
}
else
{
Children2 = ltd.Attribute("SpeciaGuest").Value.Equals("Y") ? true : ltd.Elements("Topic").Attributes("Code").Where(x => x.Value.Equals("1")).FirstOrDefault() != null ? true : false 
}
} 
}; 

Below is my XML Structure..

<?xml version="1.0" encoding="utf-8" ?>
<Document>
  <Class Code="001">
    <Subject Course="Math" AllTeachers='N' SpeciaGuest='N'></Subject>
    <Subject Course="Engish" AllTeachers='Y' SpeciaGuest='Y'></Subject>
    <Subject Course="History" AllTeachers='Y' SpeciaGuest='Y'></Subject>
  </Class>
  <Class Code="002">
    <Subject Course="Math" AllTeachers='Y' SpeciaGuest='N'>
      <Topic Code="1">LAW1</Topic>
      <Topic Code="2">
        LAW2
      </Topic>
      <Topic Code="3">
        LAW3</Topic>
      </Subject>
    <Subject Course="Engish" AllTeachers='Y' SpeciaGuest='Y'></Subject>
    <Subject Course="History" AllTeachers='Y' SpeciaGuest='Y'></Subject>
  </Class>
</Document>

Please let me know, how I can use condition to select multiple select result. Also let me know using resharper in this linq query will be fine?.

Answer 1

Because if(StyCode=0) isn’t based on the current item in the sequence, you can pull the if outside of the query:

Also note that because both of the Select clauses are selecting a single item, you don’t need an anonymous type, just select that item. That results in this:

XElement rootElement = XElement.Load(@"test.xml");
int StyCode = 0;
IEnumerable<IEnumerable<bool>> lv1s;
if (StyCode == 0)
{
    lv1s = from lv1 in rootElement.Descendants("Class")
            where lv1.Attribute("Code").Value.Equals("002")
            select (from ltd in lv1.Descendants("Subject")
                    where ltd.Attribute("Course").Value.Equals("Math")
                    select ltd.Attribute("AllTeachers").Value.Equals("Y") ? true : false);
}
else
{
    lv1s = from lv1 in rootElement.Descendants("Class")
            where lv1.Attribute("Code").Value.Equals("002")
            select (from ltd in lv1.Descendants("Subject")
                    where ltd.Attribute("Course").Value.Equals("Math")
                    select ltd.Attribute("SpeciaGuest").Value.Equals("Y") ? true : ltd.Elements("Topic").Attributes("Code").Where(x => x.Value.Equals("1")).FirstOrDefault() != null ? true : false);
}

So this is simple, and nice, but has a lot of code duplication, which is not no nice. Another road to travel down is to create a method that takes an XElement that represents ltd as well as an integer StyCode and returns a boolean indicating the appropriate value. It’s a simple enough method to write:

private static bool GetChildFromSubject(int styCode, XElement subject)
{
    if (styCode == 0)
        return subject.Attribute("AllTeachers").Value.Equals("Y");
    else
    {
        return subject.Attribute("SpeciaGuest").Value.Equals("Y") ||
                subject.Elements("Topic").Attributes("Code")
                .Any(x => x.Value.Equals("1"));
    }
}

Now we only need one query:

XElement rootElement = XElement.Load(@"test.xml");
int StyCode = 0;
var lv1s = from lv1 in rootElement.Descendants("Class")
            where lv1.Attribute("Code").Value.Equals("002")
            select (from ltd in lv1.Descendants("Subject")
                    where ltd.Attribute("Course").Value.Equals("Math")
                    select GetChildFromSubject(StyCode, ltd));

Much better.