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sunilchandra007
Active Contributor
Ask any PI developer about favorite mapping, the answer for sure would be Message Mapping. Still sometimes our favorite message mapping seem to be helpless due to its fixed target structure definition and we are forced to use java/xsl mappings or do something at adapter level for the desired output. For example you can visit some of these threads - Pass value to the node, Removing ns0 from namespace, XSLT for dynamic target field names, Add namespace in message mapping, JAVA/XSLT mapping to create SOAP envelope

Perhaps there may be many ways to manage all the above requirements but sometimes it becomes like using a cannon to kill a fly! So here we go with our favorite message mapping and see how to play around with tag name, occurrence, namespace and prefix at target side. Also we will try to pass value to structure node, seems weird? Let’s see how it is possible with simple user defined function.

In first step to access target field in udf, we take help of getParameter method of Container with parameter STRUCTURE_NODE that returns access to target field/node to which the UDF is being directly mapped to. The node needs to be type casted to structure/leaf as per the type of target field.

  • StructureNode node = ((StructureNode) container.getParameter("STRUCTURE_NODE"));

          Applicable to fields having child or sub-fields.

  • LeafStructureNode node = ((LeafStructureNode)container.getParameter("STRUCTURE_NODE"));

          Applicable to fields having no child or sub-fields.

Next step involves using node methods as per the requirements.

  • String getQName()

          Return the name of target field.

  • void setQName(String newName)

          Set the target field name with input parameter newName.

  • void setNSDeclarations(String decl)

          Set the namespace declaration and attribute with input parameter decl.

          e.g decl = " attribute1=\"a1\" attribute2=\"a2\" xmlns:prefix=\"namespace1\""

  • void setOccurances(int min, int max)

          Set the occurrence of target field with input parameter min and max.

  • void setPreValue(String prevalue)

          Add the string prevalue unescaped just after start tag of target field. Applicable only for structure field.

  • void setPostValue(String postvalue)

          Add the string postvalue unescaped just before end tag of target field. Applicable only for structure field.


For example, lets say we have the source and target structure as shown below:

Field NameOccurenceField name
Occurence
Source1..1Target1..1
    Rows0..Unbounded    Items0..Unbounded
        Key1..1        Element1..1
        Value1..1

And the requirements are..

  • The Element field name should get changed with value in Key field and should be filled with Value.
  • Output xml should have only 2 items assuming that it is coming in a particular order from source.
  • The namespace and its prefix should be Modified to "http://company.com" and pfx respectively.
  • Assign value "list of top 2 company" to Target node.

Source instance and expected result xml are as shown below.

Source InstanceResult

<?xml version="1.0" encoding="UTF-8"?>

<ns0:Source xmlns:ns0="http://test.com">

<Rows>

     <Key>CompanyA</Key>

     <Value>abc corp</Value>

</Rows>

<Rows>

     <Key>CompanyB</Key>

     <Value>xyz info</Value>

</Rows>

       ...

<Rows>

     <Key>CompanyZ</Key>

     <Value>123 ent</Value>

</Rows>

</ns0:Source>

<?xml version="1.0" encoding="UTF-8"?>

<pfx:Target xmlns:pfx="http://company.com">

list of top 2 companies

<Items>

     <CompanyA>abc corp</CompanyA>

</Items>

<Items>

     <CompanyB>xyz info</CompanyB>

</Items>

</pfx:Target>

And here comes the mapping part..

          UDF setNSDeclarations would fix namespace to http://company.com , fix prefix to pfx and assign value "list of top 2 companies" to Target node.


public String setNSDeclarations(String prefix, String nmspace ,Container container) {


     StructureNode node = ((StructureNode) container.getParameter("STRUCTURE_NODE"));

     node.setNSDeclarations(" xmlns:" + prefix + "=" + nmspace); // notice the space before xmlns:

     node.setQName(prefix + ":Target");

     node.setPreValue("list of top 2 companies");


     return"";                                   

}

  • /ns0:Target/Items=setOccurences(/ns0:Source/Rows, const(value=2))

          UDF setOccurences simply set the max occurence of Items to 2 to ensure top 2 Rows are mapped to Items.

public String setOccurences(String sourcenode, int maxOccur, Container container) {


     StructureNode node = ((StructureNode) container.getParameter("STRUCTURE_NODE"));

     node.setOccurences(0, maxOccur);


     return "";

}

  • /ns0:Target/Items/Element=setTargetFieldName(/ns0:Source/Rows/Key, /ns0:Source/Rows/Value)

          UDF setTargetFieldName dynamically changes the tag name Element.

public String setTargetFieldName(String targetFieldName, String targetFieldvalue, Container container) {


     LeafStructureNode node =((LeafStructureNode) container.getParameter("STRUCTURE_NODE"));

     node.setQName(targetFieldName);


     return targetFieldvalue;

}

At end, please note that the code discussed above uses undocumented classes/methods that are subject to change in future without notice. In short, use at your own risk as any related issues will not be supported by SAP

Reference :

Accessing Element's name in message mapping

Mapping question

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