LINQ to XML query attributes

Question

Hi

using LINQ to XML, this is a sample of my XML

<shows>
 <Show Code="456" Name="My Event Name">
   <Event Code="2453" VenueCode="39" Date="2010-04-13 10:30:00" /> 
   <Event Code="2454" VenueCode="39" Date="2010-04-13 13:30:00" /> 
   <Event Code="2455" VenueCode="39" Date="2010-04-14 10:30:00"  /> 
   <Event Code="2456" VenueCode="39" Date="2010-04-14 13:30:00" /> 
   <Event Code="2457" VenueCode="39" Date="2010-04-15 10:30:00" /> 
 </Show>

 <Show... />
 <Show... />
</shows>

How do I return a list of the Dates for a specfic show? I am passing the show code ("456") in the querystring and want all the dates/times returned as a list.

This is the code i have so far:

XDocument xDoc = XDocument.Load("path to xml");

            var feeds = from feed in xDoc.Descendants("Show")
                        where feed.Attribute("Code").Equals("456")
                        select new
                        {
                            EventDate = feed.Attribute("Date").Value
                        };

            foreach(var feed in feeds)
            {
                Response.Write(feed.EventDate + "<br />");
            }

But i get no results returned

Answer 1

Change this line:

where feed.Attribute("Code").Equals("456")

To:

where feed.Attribute("Code").Value.Equals("456")

Otherwise you're comparing the attribute as object instead of the attribute's value.

Answer 2

The attribute isn't going to equal "456" - it's an attribute, not a string. However, if you convert it to a string first, it will work.

var feeds = from feed in xDoc.Descendants("Show")
            where (string)feed.Attribute("Code") == "456"
            select new
            {
                EventDate = feed.Attribute("Date").Value
            };

An alternative would be to int to make sure it's numeric:

var feeds = from feed in xDoc.Descendants("Show")
            where (int) feed.Attribute("Code") == 456
            select new
            {
                EventDate = feed.Attribute("Date").Value
            };

EDIT: Okay, I've now got this as a short but complete program to show it working.

Note that your original code will only work if the "Show" element has a "Date" attribute - which it doesn't in your sample XML. Note that it's trying to take the "Date" from the "Show" element not the "Event" element. I'm not sure what you really wanted to do here, so I've changed the code to just cast to DateTime? instead. The code below works and prints 1 (i.e. it's found the single Show element matching the code):

using System;
using System.Linq;
using System.Xml.Linq;

public static class Test
{    
    static void Main(string[] args)
    {
        XDocument xDoc = XDocument.Load("shows.xml");
        var feeds = from feed in xDoc.Descendants("Show")
                    where (int) feed.Attribute("Code") == 456
                    select new
                    {
                        EventDate = (DateTime?) feed.Attribute("Date")
                    };

        Console.WriteLine(feeds.Count());
    }
}

If you're actually trying to find every event date within the show, you need another "from" clause to make it iterate over the events within the show:

var events = from feed in xDoc.Descendants("Show")
             where (int) feed.Attribute("Code") == 456
             // We can't use event as an identifier, unfortunately
             from ev in feed.Elements("Event")
             select new
             {
                 EventDate = (DateTime?) ev.Attribute("Date")
             };