exists (SAP Library - Partner Connectivity Kit)

exists

Use

You use this function to determine whether a particular source field exists in the XML instance to be processed. If it does, exists() returns the value true, otherwise it returns the value false.

Example

In the example below, a function declaration is to be mapped to a structure that merely comprises the technical name and the description of the function. The source structure field description is optional, however, the target structure field descriptionOfUse is mandatory (minOccurs = 1).

Source Structure (Left) and Target Structure (Right)

Field Name	minOccurs	maxOccurs	Field Name	min- Occurs	max- Occurs
FunctionDeclMsg	1	1	FunctionHeadingMsg	1	1
name	1	1	technicalName	1	1
description	0	1	descriptionOfUse	1	1
inputArg	0	64
name (Attr)	1	1
type (Attr)	1	1
returnValue	0	1
type (Attr)	1	1

Using the exists() function and other Boolean functions, you can specify a default string to be output if the description tag does not exist. This ensures that the target field descriptionOfUse is always completed and is never empty.

Message Mapping Using exists()

Target Field Mapping	Value of Constant()
/FunctionHeadingMsg=/FunctionDeclMsg
/FunctionHeadingMsg/technicalName=/FunctionDeclMsg/name
/FunctionHeadingMsg/descriptionOfUse= if( Constant() , Not(exists(/FunctionDeclMsg/description)) , /FunctionDeclMsg/description )	(No description available)

Note

The text description of the if standard function must be read as follows: if ( <result if condition true>,
<condition>,
<result if condition false>).

Example

Source Instance

Result

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

  <name>
      myFunc
  </name>

</FunctionDeclMsg>

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

<ns0:FunctionHeadingMsg
xmlns:ns0="workshopDemo">

   <technicalName>
      myFunc
   </technicalName>

   <descriptionOfUse>
      (No description available)
   </descriptionOfUse>

</ns0:FunctionHeadingMsg>