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

SAP Error Message - Details

• 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.

Smart SAP Assistant

• What is the cause and solution for SAP error message SD_CDS_ENTITY018 - @AbapCatalog.preserveKey: true missing for entity using assoc to parent ?

  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 the association to the parent. Here’s how you can do it:
  
  
  Open the CDS View Definition: Access the ABAP Development Tools (ADT) in Eclipse or the relevant transaction in SAP GUI where the CDS view is defined.
  
  
  Add the Annotation: Locate the entity definition that is causing the error and add the @AbapCatalog.preserveKey: true annotation. It should look something like this:
  @AbapCatalog.sqlViewName: 'YOUR_SQL_VIEW_NAME'
  @AbapCatalog.preserveKey: true
  define view Your_CDS_View as select from Your_Table
  ...
  
  
  Activate the CDS View: After making the changes, activate the CDS view to apply the modifications.
  
  
  Test the CDS View: Execute the CDS view to ensure that the error is resolved and that the data is being retrieved correctly.
  
  
  Related Information:
  
  CDS Views: Core Data Services (CDS) is a framework for defining semantically rich data models in SAP. It allows for the creation of views that can be consumed by various applications and tools.
  Annotations: Annotations in CDS views provide metadata that can influence the behavior of the view, such as how it is treated in terms of performance, key preservation, and more.
  Associations: Associations in CDS views define relationships between different entities, allowing for more complex data retrieval scenarios.
  
  If you continue to experience issues after making these changes, consider checking the following:
  
  Ensure that all associations are correctly defined and that the parent entities are accessible.
  Review the overall structure of the CDS view for any other potential issues that may affect its activation or execution.
  
  By following these steps, you should be able to resolve the SD_CDS_ENTITY018 error and ensure that your CDS view functions as intended.