During the last project I have been involved in developing several custom forms for SharePoint 2010 in  InfoPath 2010. During this task I have discovered and learn on my own skin many products limitation and the different approach in the way on how InfoPath works. I believe that this small guide should provides you few tricks that believe me, are good to be read before doing any dealings with InfoPath.

During the last project I have been involved in developing several custom forms for SharePoint 2010 in  InfoPath 2010. During this task I have discovered and learn on my own skin many products limitation and the different approach in the way on how InfoPath works. I believe that this small guide should provides you few tricks that believe me, are good to be read before doing any dealings with InfoPath.

Let's imagine that you today's task is to create a simple InfoPath form which

1. it sets and displays /hides few controls,
2. displays a message box,
3. based on some external parameters
4. allows the user to submit it by pressing a button.

Looks like a pretty simple task.. right? Actually.. not really if it is your first fight against InfoPath.
Let's see first what you should keep in mind, before starting any coding:

• InfoPath  2010 crashes easily. Save often.
• Custom code in InfoPath 2010  can be only written using Visual Studio 2008. And yes... if you are using Visual Studio 2010,  you need to install also the 2008 version.
• Be aware if you are using any source control program that uses read-only lock like TFS or SourceSafe. This programs locks in read-only your .csproj and InfoPath will complain

• 

Now let's see how can we accomplish those 3 simple tasks..

1) How can I hide or show my controls programmatically?
You cannot!

The only possible workaround is  using panels that you can show or hide based on a condition.
- add a panel
- insert in the panel a checkbox
- select the panel and under the Control Tools tab , click Manage Rules. 
- add a formatting rule which hides the control  if the checkbox is checked

Now you can control the panel's visibility by setting the checkboxes value. Set it to false to hide the panel.

1-b) And how can I set or get controls values programmatically?

Here is a small code snippet that would helps you in setting and reading your controls values

private void AppendFieldValue(string xPath, string xValue, bool isNi)
{
    string oldValue = GetFieldValue(xPath);
    SetFieldValue(xPath, String.Concat(oldValue, xValue), isNi);
}

private void SetFieldValue(string xPath, string xValue, bool isNil)
{
    try
    {
        XPathNavigator xnDoc = this.MainDataSource.CreateNavigator();
        XPathNavigator xnMyField = xnDoc.SelectSingleNode(xPath, this.NamespaceManager);

        if (isNil)
        {
            if (xnMyField.MoveToAttribute("nil", "http://www.w3.org/2001/XMLSchema-instance"))
                xnMyField.DeleteSelf();
        }

        xnMyField.SetValue(xValue);
        xnDoc = null;
        xnMyField = null;
    }
    catch (Exception ex)
    {
        throw new Exception(xPath + ":" + xValue + ":" + ex.StackTrace, ex);
    }
}

private string GetFieldValue(string xPath)
{
    XPathNavigator xnDoc = this.MainDataSource.CreateNavigator();
    XPathNavigator xnMyField = xnDoc.SelectSingleNode(xPath, this.NamespaceManager);
    if (xnMyField != null)
    {
        return xnMyField.Value;
    }
    else
    {
        return string.Empty;
    }
}

2) Can I create a message box to alert users in infopath 2010?

No, you cannot. You have to play a little with Infopath Views. Create a view wich contains your text message and  just switch to the view whenever you need to print the message.

this.ViewInfos.SwitchView("YOURVIEW");

3) Can I pass any parameter to my custom form when I render it in SharePoint through FormServer.aspx?

Yes. The best way to accomplish that is using querystrings. Call the FormServers.aspx by passing the querystring and get the value from code in the FormEvents_Loading event. Here is and example: call you form by passing a a querystring:

http://yourServer/_layouts/FormServer.aspx?XsnLocation=~sitecollection/FormServerTemplates/YourTemplate.xsn&OpenIn=Browser&SaveLocation=http://yourserver/yourDocLib& myQueryStringValue=helloWord

And add this snippet into the FormEvents_Loading event:

public void FormEvents_Loading(object sender, LoadingEventArgs e)
{
    try
    {
    if (e.InputParameters.ContainsKey("myQueryStringValue"))
        string myQueryStringValue = e.InputParameters["myQueryStringValue"];
    }
    catch (Exception ex)
    {
       //do something
    }
}

4) How to programmatically submit your form to document library?

First create a new data connection in Infotpath 2010 as a Submit and To a Document Library on a SharePoint site. Don't't worry in entering any SharePoint Server's url and destination document library, because this values can be overridden in code. Once you have created the new Data Connection, name it as SharePoint Library Submit.

Now add a simple button, and in the buttons propery windows select Action= Submit, press Submit Options and check Perform Custom action using  Code and finally press Edit Code.

Add the following code in the FormEvents_Submit event

public void FormEvents_Submit(object sender, SubmitEventArgs e)
{
    try
    {
        FileSubmitConnection spConn = DataConnections["SharePoint Library Submit"] as FileSubmitConnection;
        spConn.FolderUrl = "http://yourServer/yourDestinationDocLibUrl/"l;
        spConn.Filename.SetStringValue("YourFileName.xml");
        spConn.Execute();
        e.CancelableArgs.Cancel = false;
    }
    catch (Exception ex)
    {
        e.CancelableArgs.Cancel = true;
    }
}

I hope this small guide helps you in this basic tasks when developing custom forms in Infopath 2010 for SharePoint 2010.