How To Fix DT279 - Field &: Reference & to class w/o interface cannot be used in DB table &

SAP Error Message - Details

• Message type: E = Error

• Message class: DT - Table activation (incl. indexes)

• Message number: 279

• Message text: Field &: Reference & to class w/o interface cannot be used in DB table &

What causes this issue?

In the definition for a database table, you used a reference to a class
or an interface. This is not possible because the databases do not
recognize such references, that is, fields with this type cannot be
created in the database.

System Response

The activation is rejected.

How to fix this error?

In database tables, you can choose between different types. You can
display these using the input help for the data type.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message DT279 - Field &: Reference & to class w/o interface cannot be used in DB table & ?

  The SAP error message DT279 indicates that there is an issue with a reference to a class that does not implement an interface in the context of a database table definition. This typically occurs when you are trying to use a reference type in a database table that is not compatible with the requirements of the database layer.
  Cause:
  
  Class Definition: The class you are trying to reference in the database table does not implement any interface. In ABAP, only reference types that implement an interface can be used in database tables.
  Data Dictionary: The data dictionary (DDIC) is strict about the types of references that can be used in database tables. If a reference type does not meet the criteria, it will throw this error.
  Inconsistent Data Model: There may be inconsistencies in your data model where a reference type is expected to be used, but the underlying class does not conform to the necessary structure.
  
  Solution:
  
  
  Implement an Interface: Modify the class that is being referenced in the database table to implement an appropriate interface. This will allow the reference to be valid in the context of the database table.
  
  Open the class in the ABAP Workbench (SE80 or SE24).
  Implement the required interface(s) that are relevant to your use case.
  
  
  
  Change the Data Type: If implementing an interface is not feasible, consider changing the data type in the database table to a compatible type (e.g., a simple data type or a different reference type that implements an interface).
  
  Go to the Data Dictionary (SE11).
  Modify the field definition to use a compatible type.
  
  
  
  Check Dependencies: Ensure that there are no other dependencies or references that might be causing this issue. Sometimes, other parts of the code or data model may need to be adjusted.
  
  
  Re-activate Objects: After making changes, ensure that you re-activate the class and the database table to reflect the changes.
  
  
  Related Information:
  
  ABAP Classes and Interfaces: Understanding the difference between classes and interfaces in ABAP is crucial. Classes can implement multiple interfaces, which allows for polymorphism and better design.
  Data Dictionary (DDIC): Familiarize yourself with the Data Dictionary in SAP, as it governs how data types are defined and used within the system.
  SAP Notes: Check SAP Notes for any specific guidance or patches related to this error message, as there may be updates or known issues that could provide additional context or solutions.
  
  If you continue to face issues after trying the above solutions, consider reaching out to your SAP Basis or ABAP development team for further assistance.