Linq and untyped DataSets

As a small update to the previous post - if you don't fancy looking through each table in an untyped dataset then linq is your friend. For instance to join information from two of the yr.no-service tables you can do this:

// Join "time" and "temperature"-tables,
// Get id, temperature, from time and to time
var query =
from time in ds.Tables["time"].AsEnumerable()
join temp in ds.Tables["temperature"].AsEnumerable()
on time.Field<int>("time_id") equals
temp.Field<int>("time_id")
select new
{
TemperatureId = time.Field<int>("time_id"),
Tempearature = temp.Field<string>("value"),
FromTime = time.Field<string>("from"),
ToTime = time.Field<string>("to"),
};


// Simple output
foreach (var tempInfo in query)
{
Console.WriteLine("{0} - {1}:\t{2}",
tempInfo.FromTime,
tempInfo.ToTime,
tempInfo.Tempearature);
}

For more information check this link on MSDN.

Reading weather data from www.yr.no

Thanks to Sjur for the tip about the weather service at www.yr.no, which actually has a web service publishing pure xml data.

To access a weather service for your favourite location, look it up through the yr.no search and add "Varsel.xml" to the URL.

Access from C# / .Net:

// Load xml from URL
string feedURL = @"http://www.yr.no/sted/Norge/Oslo/Oslo/Oslo/Varsel.xml";
XmlDocument xDoc = new XmlDocument();
xDoc.Load(feedURL);

// Get forecast information
XmlNodeList forecast = xDoc.GetElementsByTagName("forecast");

// Read into dataset
DataSet ds = new DataSet();
StringReader readerStream = new StringReader(forecast[0].OuterXml);
ds.ReadXml(readerStream);

And you have an untyped dataset full of weather information.

Thank you yr.no.

(check the next post for how to read the data with Linq)