InfoPath Dev

Hello,

I have a repeating table that has a button to go get the "ExtPartNum" from another view called "Get Part" and also set the CurrentRow field from my Line field. The "Get Part" view is a search with a text box and button to retrieve a web service and fill out the repeating table with a matching Part Number pattern. So I created a rule to set a field value for the main view's ExtPartNum to equal to the selected PartNum. Here is my Source code below for those 2 button rules for InfoPath. I get this error when clicking on the button on the Get Part view.

Error :

System.Xml.XPath.XPathException
Expression must evaluate to a node-set.

Rule on Main View: 

   <xsf:ruleSet name="ruleSet_13">
   <xsf:rule caption="Rule 1" isEnabled="yes">
    <xsf:assignmentAction targetField="../../my:CurrentRow" expression="my:line"></xsf:assignmentAction>
    <xsf:switchViewAction view="Get Part"></xsf:switchViewAction>
   </xsf:rule>
  </xsf:ruleSet>

 Rule on Get Part View:

  <xsf:ruleSet name="ruleSet_14">
   <xsf:rule caption="SetExtPartNum" isEnabled="yes">
    <xsf:assignmentAction targetField="xdXDocument:get-DOM()/my:travelRequest/my:group1/my:Row[position() = /my:travelRequest/my:CurrentView]/my:ExtPartNum" expression="ns4:PartNumber"></xsf:assignmentAction>
    <xsf:switchViewAction view="Create New Request"></xsf:switchViewAction>
   </xsf:rule>
  </xsf:ruleSet>

The weird thing is that it correctly sets the value to the correct row but throws the error "Expression must evaluate to a node-set." for some odd reason.

Ok, it looks like I might of caused my own error. I also had old code from the button event that produced that error and after commenting it out it stopped producing it. So the problem I have now is that Web based Infopath Forms do not support the XPath function position(). So it looks like I might have to write c# managed code to replicated the same thing unless anybody knows another way through Rule based. If not, a sample c# code would be great.

 Thanks,

Vinny

Ok, here is the c# managed code equivalent.

XPathNavigator container = root.SelectSingleNode("/my:travelRequest/my:group1/my:Row[position() = /my:travelRequest/my:CurrentRow]/my:ExtPartNum", NamespaceManager);

XPathNavigator container2 = root.SelectSingleNode("/my:travelRequest/my:group1/my:Row[position() = /my:travelRequest/my:CurrentRow]/my:Description", NamespaceManager);