Query DataConnection in Infopath Web-enabled Form when selecting value of dropdownlost (with Managed Code)

You don't always need to load your dataconnection before the form is loaded (performance reasons), sometimes you want to load a different dataconnection when a certain value is selected. I use the example of a dropdownlist, and every value of the dropdownlist will load an other dataconnection into another dropdownlist.



Add the 2 dropdownlists, the second dropdownlist must have a connection with a datasource (I use an embedded Xml file dc.xml). When creating this dataconnection, please deselect the setting "Automatically retrieve dat when form is opened".




What you will need after you created the controls in infopath, open VSTA (alt+shift+F12). Add following code fragment into the InternalStartup method:

this.EventManager.XmlEvents["/my:myFields/my:Type"].Changed += new XmlChangedEventHandler(TypeChanged);

You also need to add the TypeChanged methods:

void TypeChanged(object sender,XmlEventArgs e)
{
  string type = e.NewValue; //the selected value of the type dropdownlist
  
  //I just added one dataconnection called dc (value when you select POST)
  //You need to put here code (switch) for all the values in the type ddl    
  DataSource ds = this.DataSources[type];
  DataConnection dc = ds.QueryConnection;

  dc.Execute();
}

When you use the Execute method of a dataconnection, you must change following setting (it is like the ASP.NET AutoPostBack setting), otherwise your dataconnection will not be loaded!! (when you just changed a value of another field, you don't need to change this setting).




Change the standard option (postback settings): "Only when necessary for correct rendering of the form (recommended)" to "Always"


Remarks:
When you use Mananged Code in web-enabled form, uou must publish it as an administrator approved template (check out blogpost http://spsfactory.blogspot.com/2007/01/walkthrough-publishing-administrator.html )

Handle the InfoPath Forms Services by yourself (in a Custom WebPart to view a web-enabled Infopath 2007 Form)

To understand this post well, please go through this post first:
- Hosting the InfoPath 2007 Form Editing Environment in a Custom Web Form

Sometimes you don't want to popup an error by InfoPath Forms Services (it will log this also in the EventLog), see image below. You want to catch the error in code and do some custom logging (or other stuff)

I will use the example when a dataconnection (webservices) in the form gives a time-out.

Preceding:
First keep in mind that we will bind the dataconnection-webservice to its control in code, so you have to deselect - Automatically retrieve data when form is opened (when adding a data-connection in InfoPath). Also don't forget to link the control with the dataconnection in infopath designer

What we gonna do in code:
- Add a handler that will get you into the Initialize methods of the XmlFormView
- Get the right dataconnection, execute it (so it will get the data and bind to the control)
- Add a "try/catch" block around this code

The code:

void viewform_Initialize(object sender, InitializeEventArgs e)
{
   try
   {
      DataConnection dc = _viewform.XmlForm.DataSources["GetGAL"].QueryConnection;
      dc.Execute();
   }
   catch (System.Net.WebException webEx)
   {
      WarmUpWebService();
      ReloadWebPart();
      //Log, ...
   }
   catch (Exception ex)
   {     
      Logger.Log(ex, ...);
   }
}


Some other InfoPath blogs:
InfoPath Developer Portal 
Designing Form Templates With The New Features Of InfoPath 
InfoPath BLOG Site