How To Fix SD_CDS_ENTITY018 - @AbapCatalog.preserveKey: true missing for entity using assoc to parent

SD_CDS_ENTITY018 - Overview

• Message type: E = Error

• Message class: SD_CDS_ENTITY - Messages for STOBS/entities

• Message number: 018

• Message text: @AbapCatalog.preserveKey: true missing for entity using assoc to parent

A child entity in a BO structure can only have one parent entity. A
parent entity has the "composition of" syntax addition. The found child
entity has two parents, which is not allowed.

Error message extract from SAP system. Copyright SAP SE.

SD_CDS_ENTITY018 - Details

• The SAP error message SD_CDS_ENTITY018 @AbapCatalog.preserveKey: true missing for entity using assoc to parent typically occurs in the context of Core Data Services (CDS) views in SAP ABAP when there is an issue with the definition of a CDS entity that is using associations to parent entities.
  
  Cause:
  This error indicates that the CDS entity in question is using an association to a parent entity, but it does not have the @AbapCatalog.preserveKey: true annotation defined. The preserveKey annotation is necessary when you want to ensure that the key fields of the entity are preserved when the entity is being used in a join or association context. Without this annotation, the system cannot guarantee that the key fields will be maintained, leading to potential issues in data retrieval and integrity.
  
  Solution:
  To resolve this error, you need to modify the CDS view definition to include the @AbapCatalog.preserveKey: true annotation for the entity that is using