How do I fix object reference not set to an instance of an object?

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I get CompletedDate from XML document element name CompDate. This is an optional element. When the XML document has a CompDate element my VB.NET code works. However when the XML document does not have CompDate element, I get Object reference not set to an instance of an object?

How do I fix this so it works whether or not the CompDate element exist in the XML Document?

XML Document

XML

<Integration>
   <Case>
     <CaseEvent ID="252949395">
	<CompDate>06/01/2019</CompDate>
     </CaseEvent>
   </Case>
   <IntegrationConditions>
      <IntegrationCondition>
	 <NotificationEvent elementKey="252949395">InsertPWBRorAOS</NotificationEvent>
      </IntegrationCondition>
   </IntegrationConditions>
</Integration>

What I have tried:

VB.NET code

VB

Dim strEventId As String

strEventId = aobjxmlNotificationEventNode.SelectSingleNode("@elementKey").InnerText

objInsertPWBRorAOS.CompletedDate = CDate(aobjXmlInputDoc.DocumentElement.SelectSingleNode("Case/CaseEvent[@ID=" + strEventId + "]/CompDate").InnerText)

Posted 18-Jul-19 12:28pm

Member 11403304

Updated 18-Jul-19 12:56pm

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Patrice T · Accepted Answer · 2019-07-18T12:56:00

Quote:
How do I fix this so it works whether or not the CompDate element exist in the XML Document?

Rather simple, either you check that element exist before reading its value, either you read the value to a temp variable and the check if variable is expected object or nothing before storing value.
Should like that:

VB

Tmp= CDate(aobjXmlInputDoc.DocumentElement.SelectSingleNode("Case/CaseEvent[@ID=" + strEventId + "]/CompDate").InnerText)
If Tmp Is Nothing Then objInsertPWBRorAOS.CompletedDate = Tmp