How To Fix WER168 - Expression assignment is not supported for this parameter

SAP Error Message - Details

• Message type: E = Error

• Message class: WER - Messages for the package WER

• Message number: 168

• Message text: Expression assignment is not supported for this parameter

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message WER168 - Expression assignment is not supported for this parameter ?

  The SAP error message WER168: "Expression assignment is not supported for this parameter" typically occurs in the context of ABAP Web Dynpro or Web Dynpro for ABAP development, particularly when dealing with context node attributes or component controller parameters.
  
  Cause
  
  Expression assignment is attempted on a parameter or attribute that does not support it.
  
  In Web Dynpro, parameters or context attributes can be assigned values either by direct assignment or by expression assignment (using binding expressions). However, not all parameters or attributes support expression assignment.
  For example, if you try to assign a value to a parameter or context attribute using an expression (like a binding expression or a formula) where only direct assignment is allowed, the system raises this error.
  Common scenarios include:
  
  Trying to assign an expression to an importing parameter of a component controller or a view controller.
  Assigning an expression to a parameter that is not designed to accept expressions (e.g., parameters that are only for input or output).
  Using expression assignment in places where only static or direct assignment is supported.
  
  
  Solution
  
  Use direct assignment instead of expression assignment for the parameter.
  
  Steps to resolve:
  
  
  Check the parameter or attribute definition:
  
  Verify if the parameter supports expression assignment.
  Parameters that are importing or exporting may have restrictions.
  
  
  
  Change the assignment method:
  
  Instead of using an expression (e.g., binding expression), assign the value directly in the code or via method calls.
  For example, in the Web Dynpro context, use wdContext->getChildNode(...)->setAttribute(...) to assign values directly.
  
  
  
  Review the Web Dynpro context mapping:
  
  Ensure that the context attribute or parameter is correctly mapped and supports the intended assignment method.
  
  
  
  If you are using the Web Dynpro Explorer:
  
  Check the property or parameter settings in the component controller or view controller.
  Remove any expression bindings from parameters that do not support them.
  
  
  
  
  Related Information
  
  
  SAP Note / Documentation:
  
  This error is documented in SAP Web Dynpro development guides.
  SAP Community forums often discuss similar issues related to context attribute assignments.
  
  
  
  Web Dynpro Concepts:
  
  Understand the difference between direct assignment and expression assignment.
  Parameters can be importing, exporting, or changing, and their assignment capabilities differ.
  
  
  
  Debugging Tips:
  
  Trace where the assignment is happening.
  Check the Web Dynpro context and parameter definitions.
  Use the Web Dynpro debugger to inspect parameter values and assignments.
  
  
  
  
  Summary
  
  
  
  Aspect
  Details
  
  
  
  
  Error
  WER168: Expression assignment is not supported for this parameter
  
  
  Cause
  Attempting to assign a value using an expression to a parameter that does not support it
  
  
  Solution
  Use direct assignment instead of expression assignment; check parameter definitions
  
  
  Context
  Web Dynpro for ABAP, context attributes, component/view controller parameters
  
  
  
  
  If you provide the exact code snippet or scenario where this error occurs, I can help you with a more specific solution.