Help for writing a LINQ query !

Mohammad Dayyan

Hello. I have a XML file like this :

I'm gonna select the Part element with maximum ID. I've used this query, but it's wrong.

XElement xElement = XElement.Parse(xmlSTR);
var max = from q in xElement.Descendants("Part" )
where q.Attribute("ID" ).Value == q.Attributes("ID" ).Max().Value
select q;
Console.WriteLine(max.First());

what do you suggest ? thank you.

Howard Richards

XAttribute.Value is always a string. You need to convert to an integer.

XElement e = XElement.Parse(xmlSTR);

        // get elements as integers
        var values = from q in e.Descendants("Part")
                     select Convert.ToInt32(q.Attribute("ID").Value);
        Console.WriteLine("Found {0} elements", values.Count());
        
        // get highest value
        var highest = values.Max();
        Console.WriteLine("Highest value is {0}", highest);

        // get Part element with highest
        var highestElement = (from q in e.Descendants("Part")
                              where q.Attribute("ID").Value == highest.ToString()
                              select q).First();

        //report
        Console.WriteLine("Highest element: {0}", highestElement.ToString());

        Console.ReadKey();

'Howard

Mohammad Dayyan

Thank you. So we can't do it within one query ?

Fernando Soto

Hi Howard; This should do what you want.

XElement xElement = XElement.Parse(xmlSTR);
var max = (from q in xElement.Descendants("Part")
let val = Convert.ToInt32(q.Attribute("ID").Value)
orderby val descending
select q).First();

MessageBox.Show(max.ToString());

Fernando

Howard Richards

Thanks but it wasn't me that asked

'Howard

Howard Richards

I wrote it as separate ones for clarity - you can just replace the variables in the later queries for the original query - just like subqueries in SQL for example.

'Howard

Mohammad Dayyan

Great, thanks

Fernando Soto

Hi Mohammad; This should do what you want.

XElement xElement = XElement.Parse(xmlSTR);
var max = (from q in xElement.Descendants("Part")
let val = Convert.ToInt32(q.Attribute("ID").Value)
orderby val descending
select q).First();

MessageBox.Show(max.ToString());

Fernando

Fernando Soto

Not a problem, glad to help.