Saturday, July 28, 2007

Getting .NET datasets in Flex through webservices

The current support in Flex for .NET datasets is rather 'limited' to say the least. This is a pitty because most .NET developers make use of datasets and the missing support currently prevents major adoption of Flex by the .NET community.

Although this solution doesn't add complete dataset support to Flex it at least allows you to get the records of a .NET dataset (or a datatable) in Flex through an easy webservice call.

Up till now the typical suggestion is to create a class in .NET that matches the datatable layout, create an array based on this class and fill the array with the records of the datatable.

There is however a much easier solution. Your WebMethod in .NET should look like this:

[WebMethod]
public XmlDocument GetAllUsers()
{
dsBC dsBC1 = new dsBC();
// here you should fill the datatable with database records
return GetXml(dsBC1.bcUser);
}

public XmlDocument GetXml(DataTable dt)
{
System.IO.StringWriter sw = new System.IO.StringWriter();
dt.WriteXml(sw);
sw.Close();
XmlDocument xd = new XmlDocument();
xd.LoadXml(sw.ToString());
return xd;
}

When calling the GetAllUsers web method from Flex you can simply bind for example a datagrid to the event.result object.

Dates are returned in W3C format by .NET! Therefore you should convert them to 'real' Flex dates by using the DateUtil routines in corelib.

3 comments:

Steven said...

This is a great tip, but how can I send the data back to a webservice? i.e. an editable datagrid?

Ria Flex said...

The only way I found was webmethods with a parameter per field: updateCustomer(id, firstName, lastName, ...). It's not ideal but it works :)

Corey said...

Thanks for the great tip. I use the DataSet class all the time in my .NET web services. Your solution has made my Flex colleague happy as a kitten with a Q-tip.