How To Fix /IWBEP/CM_SBMC_MPC021 - Right End Cardinality is not specified for Association '&1'

SAP Error Message - Details

• Message type: E = Error

• Message class: /IWBEP/CM_SBMC_MPC -

• Message number: 021

• Message text: Right End Cardinality is not specified for Association '&1'

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message /IWBEP/CM_SBMC_MPC021 - Right End Cardinality is not specified for Association '&1' ?

  The SAP error message /IWBEP/CM_SBMC_MPC021 indicates that there is an issue with the definition of an association in your OData service model. Specifically, it states that the right end cardinality for an association is not specified. This typically occurs in the context of defining associations between entities in the OData service's metadata.
  Cause:
  
  Missing Cardinality Definition: The error arises when an association is defined between two entities, but the cardinality for the right end of the association is not specified. Cardinality defines how many instances of one entity can be associated with instances of another entity (e.g., one-to-one, one-to-many, many-to-many).
  Model Definition Issues: This can happen if the data model is not correctly defined in the ABAP code or if there are inconsistencies in the metadata definitions.
  
  Solution:
  To resolve this error, you need to ensure that the cardinality for the right end of the association is properly defined in your OData service model. Here are the steps to do this:
  
  
  Check the Data Model: Review the data model in your ABAP code where the association is defined. Look for the association declaration and ensure that both ends (left and right) have their cardinalities specified.
  
  
  Define Cardinality: If the right end cardinality is missing, you need to add it. The cardinality is typically defined in the format:
  
  1 for one (exactly one instance)
  0..1 for zero or one (optional)
  * for many (zero or more)
  
  For example, if you have an association between EntityA and EntityB, and EntityA can have many EntityB instances, you might define it as:
  association to EntityB
  cardinality: "1" to "*" 
  
  
  Regenerate the OData Service: After making changes to the model, regenerate the OData service to ensure that the changes take effect. This can usually be done through transaction /IWFND/MAINT_SERVICE in the SAP GUI.
  
  
  Test the Service: Once the service is regenerated, test it to ensure that the error is resolved and that the associations are functioning as expected.
  
  
  Related Information:
  
  OData Service Development: Familiarize yourself with the OData service development in SAP, including how to define entities, associations, and their cardinalities.
  SAP Documentation: Refer to the official SAP documentation for OData services and the specific version of the SAP Gateway you are using for more detailed guidance.
  Debugging: If the issue persists, consider using debugging tools to trace the execution and identify where the model definition might be going wrong.
  
  By following these steps, you should be able to resolve the error message /IWBEP/CM_SBMC_MPC021 and ensure that your OData service is correctly defined.