BizTalk: xpath: How to work with empty and Null elements in the Orchestration

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BizTalk: xpath: How to work with empty and Null elements in the Orchestration

The problem is with the Empty-Null cases in the xpath expressions.

Is it possible to separate all these cases in Expression shapes of the Orchestration xpath?

For example, we have the record with <name> element, in such flavors:

case: "NonEmpty"

<ns0:People>
<ns0:Name>Name_0</ns0:Name>
<ns0:IsDependent>IsDependent_0</ns0:IsDependent>
..

case: "Empty"

  <ns0:People>
    <ns0:Name></ns0:Name>
    <ns0:IsDependent>IsDependent_0</ns0:IsDependent>
..

case: "OneTag"

<ns0:People>
<ns0:Name/>
<ns0:IsDependent>IsDependent_0</ns0:IsDependent>
..

case: "Null"

<ns0:People>

<ns0:IsDependent>IsDependent_0</ns0:IsDependent>
..

Is it possible to separate all these cases in Expression shapes of the Orchestration?

There is no information into the MSDN about this [http://msdn.microsoft.com/en-us/library/aa561906(BTS.10).aspx]

I tried to use the xpath() function in two variants, one with "string(xpath_expression)" second with "xpath_expression"

Expression Shape:

[

System.Diagnostics.Trace.WriteLine("== with string() ====================================================================");

var_xpathString = "string(/*[local-name()='Root' and namespace-uri()='http://MapTest.IncPerson']/*[local-name()='People' and namespace-uri()='http://MapTest.IncPerson']/*[local-name()='Name' and namespace-uri()='http://MapTest.IncPerson'])";

System.Diagnostics.Trace.WriteLine("[" + System.Convert.ToString(xpath (msg_SourceRoot, var_xpathString)) + "]");

if ( xpath (msg_SourceRoot, var_xpathString) == null)
{ System.Diagnostics.Trace.WriteLine("Name == null"); }

else if ( xpath (msg_SourceRoot, var_xpathString) == "")
{ System.Diagnostics.Trace.WriteLine("Name == Empty");}

else
{ System.Diagnostics.Trace.WriteLine("Name != null && Name != Empty"); }

System.Diagnostics.Trace.WriteLine("-- no string() --------------------------------------------------------------------");
var_xpathString = "/*[local-name()='Root' and namespace-uri()='http://MapTest.IncPerson']/*[local-name()='People' and namespace-uri()='http://MapTest.IncPerson']/*[local-name()='Name' and namespace-uri()='http://MapTest.IncPerson']";

System.Diagnostics.Trace.WriteLine("[" + System.Convert.ToString(xpath (msg_SourceRoot, var_xpathString)) + "]");

if ( xpath (msg_SourceRoot, var_xpathString) == null)
{ System.Diagnostics.Trace.WriteLine("Name == null"); }

else if ( xpath (msg_SourceRoot, var_xpathString) == "")
{ System.Diagnostics.Trace.WriteLine("Name == Empty"); }

else
{ System.Diagnostics.Trace.WriteLine("Name != null && Name != Empty");}

]

I.e. the "string(xpath_expression)" expression is used in the firs section, the"xpath_expression" is used in the second.

Result is:

"NonEmpty" == with string() ====================================================================
[Name_0]
Name != null && Name != Empty
-- no string() --------------------------------------------------------------------
[Microsoft.XLANGs.Core.Part+ArrayBasedXmlNodeList]
Name != null && Name != Empty

"Empty"== with string() ====================================================================
[]
Name == Empty
-- no string() --------------------------------------------------------------------
[Microsoft.XLANGs.Core.Part+ArrayBasedXmlNodeList]
Name != null && Name != Empty

"OneTag"== with string() ====================================================================
[]
Name == Empty
-- no string() --------------------------------------------------------------------
[Microsoft.XLANGs.Core.Part+ArrayBasedXmlNodeList]
Name != null && Name != Empty

"Null"== with string() ====================================================================
[]
Name == Empty
-- no string() --------------------------------------------------------------------
[]
Name == null

Conclusion:

* I cannot separate the cases "Empty" and "OneTag"

* I can separate the cases "Empty and "Null" with "xpath_expression", not with "string(xpath_expression)" expression
* "Null" case does not throw an exception.
* xpath expression inside string() works fine to get all three cases ("Empty", "OneTag", "Null") under one "if" statement. And here it returns only "" (Empty string).