How do I use XML prefixes in C#?

Question

EDIT: I have now published my app: http://pastebin.com/PYAxaTHU

I was trying to make console-based application that returns my temperature.

using System;
using System.Xml;


namespace GetTemp
{
    class Program
    {
        static void Main(string[] args)
        {
            XmlDocument doc = new XmlDocument();
            doc.LoadXml(downloadWebPage(
             "http://www.andrewmock.com/uploads/example.xml"
            ));

            XmlNamespaceManager man = new XmlNamespaceManager(doc.NameTable);
            man.AddNamespace("aws", "www.aws.com/aws");

            XmlNode weather = doc.SelectSingleNode("aws:weather", man);
            Console.WriteLine(weather.InnerText);
            Console.ReadKey(false);
        }


    }
}

Here is the sample XML:

<aws:weather xmlns:aws="http://www.aws.com/aws">
   <aws:api version="2.0"/>
   <aws:WebURL>http://weather.weatherbug.com/WA/Kenmore-weather.html?ZCode=Z5546&Units=0&stat=BOTHL</aws:WebURL>
   <aws:InputLocationURL>http://weather.weatherbug.com/WA/Kenmore-weather.html?ZCode=Z5546&Units=0</aws:InputLocationURL>
   <aws:station requestedID="BOTHL" id="BOTHL" name="Moorlands ES" city="Kenmore" state=" WA" zipcode="98028" country="USA" latitude="47.7383346557617" longitude="-122.230278015137"/>
   <aws:current-condition icon="http://deskwx.weatherbug.com/images/Forecast/icons/cond024.gif">Mostly Cloudy</aws:current-condition>
   <aws:temp units="&deg;F">40.2</aws:temp>
   <aws:rain-today units=""">0</aws:rain-today>
   <aws:wind-speed units="mph">0</aws:wind-speed>
   <aws:wind-direction>WNW</aws:wind-direction>
   <aws:gust-speed units="mph">5</aws:gust-speed>
   <aws:gust-direction>NW</aws:gust-direction>
</aws:weather>

I'm just not sure how to use XML prefixes correctly here. What is wrong with this?

Answer 1

OK, so based on this XML from the example:

<aws:weather xmlns:aws="http://www.aws.com/aws">
   <aws:api version="2.0"/>
   <aws:WebURL>http://weather.weatherbug.com/WA/Kenmore-weather.html?ZCode=Z5546&Units=0&stat=BOTHL</aws:WebURL>
   <aws:InputLocationURL>http://weather.weatherbug.com/WA/Kenmore-weather.html?ZCode=Z5546&Units=0</aws:InputLocationURL>
   <aws:station requestedID="BOTHL" id="BOTHL" name="Moorlands ES" city="Kenmore" state=" WA" zipcode="98028" country="USA" latitude="47.7383346557617" longitude="-122.230278015137"/>
   <aws:current-condition icon="http://deskwx.weatherbug.com/images/Forecast/icons/cond024.gif">Mostly Cloudy</aws:current-condition>
   <aws:temp units="&deg;F">40.2</aws:temp>
   <aws:rain-today units=""">0</aws:rain-today>
   <aws:wind-speed units="mph">0</aws:wind-speed>
   <aws:wind-direction>WNW</aws:wind-direction>
   <aws:gust-speed units="mph">5</aws:gust-speed>
   <aws:gust-direction>NW</aws:gust-direction>
</aws:weather>

You're trying to read out which value?

What's wrong with your code is that your XML namespace is wrong:

You have:

XmlNamespaceManager man = new XmlNamespaceManager(doc.NameTable);
man.AddNamespace("aws", "www.aws.com/aws");

but the XML namespace is: http://www.aws.com/aws

so you should have:

 XmlNamespaceManager man = new XmlNamespaceManager(doc.NameTable);
 man.AddNamespace("aws", "http://www.aws.com/aws");

So to read out eg the temperature, use something like this:

XmlDocument doc = new XmlDocument();
doc.LoadXml(downloadWebPage("http://www.andrewmock.com/uploads/9/1/0/7/9107466/example.xml"));

XmlNamespaceManager man = new XmlNamespaceManager(doc.NameTable);
man.AddNamespace("aws", "http://www.aws.com/aws");

XmlNode temps = doc.SelectSingleNode("/aws:weather/aws:temp", man);

string tempValue = temps.InnerText;

Gives you a value of "40.2" in tempValue

And as Henk Holtermann recommended in his comment - it would be even easier to read this with Linq-to-XML:

XDocument doc = XDocument.Load("http://www.andrewmock.com/uploads/9/1/0/7/9107466/example.xml");

XNamespace aws = "http://www.aws.com/aws";

var weatherNode = doc.Document.Descendants(aws + "weather");
var tempNode = weatherNode.Descendants(aws + "temp").FirstOrDefault();

string tempValue = tempNode.Value;

Of course, this doesn't include any error handling just yet (checking for things like the weatherNode being NULL and stuff like that) - but it gives you an idea.