Pass in any parameter to an InfoPath form with one piece of code

One thing that’s lacking in Microsoft InfoPath 2007 is the ability to simply map input parameters to the main data source (which is most likely where you want them to go). 

Unfortunately there’s no getting around the need to write code to ‘receive’ your input parameters, but with a thought you’ll be able to pass
in parameters with the same name as the fields in your form and have one block of code to paste into the code behind all forms – that will work for all. 

This includes a couple of utility functions that make life a bit easier when coding around fields in the form.
The ‘DeleteSelf’ line around the nil attribute is something that apparently gets around data type errors if you’ve got fields that aren’t just ‘string’ – e.g. ‘number’ etc.  I found this worked in the InfoPath client, but not in a browser (and had to change my field data type back to string, and add some regexp validation).

        public void FormEvents_Loading(object sender, LoadingEventArgs e)

            //Try and identify any input parameters and put them into their requisite places in the main data source
            foreach (string parameter in e.InputParameters.Keys)

                //Try and find in the main data source, then set the value
                XPathNavigator formNode = SelectSingleNode(String.Format("//my:{0}", parameter));
                if (formNode != null)
                    if (formNode.MoveToAttribute("nil", ""))

                    formNode = SelectSingleNode(String.Format("//my:{0}", parameter));
        /// <summary>
        /// Select a single node from the Main data Source
        /// </summary>
        /// <param name="xpath"></param>
        /// <returns></returns>
        private XPathNavigator SelectSingleNode(string xpath)
            string ns = LookupNamespace("my");
            XPathNavigator navigator = MainDataSource.CreateNavigator();
            return navigator.SelectSingleNode(xpath, NamespaceManager);
        private string LookupNamespace(string ns)
            return NamespaceManager.LookupNamespace(ns);