How To Fix SDDL_PARSER_MSG170 - $$projection is not supported in abstract entities

SAP Error Message - Details

• Message type: E = Error

• Message class: SDDL_PARSER_MSG - Message Class for DDL Parser

• Message number: 170

• Message text: $$projection is not supported in abstract entities

Self-Explanatory Message

Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.

To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.

Unfortunately, there isn't any extra information in this error notice.

What else can you do?

First, use our AnswerBot below to get a possible cause and solution (requires a premium subscription).

Also, review the in-depth Common Questions & Answers listed below; you could discover a solution there or be able to connect with others who have faced similar challenges.

You can also try searching the SAP support portal (support.sap.com) but you need a special user ID to access it. It is possible that an SAP support note exists that provides additional details about the mistake or even steps for fixing it.

Smart SAP Assistant

• What is the cause and solution for SAP error message SDDL_PARSER_MSG170 - $$projection is not supported in abstract entities ?

  The SAP error message SDDL_PARSER_MSG170 with the description $$projection is not supported in abstract entities typically occurs in the context of SAP's OData services or when working with the SAP Gateway. This error indicates that there is an attempt to use a projection (which is a way to select specific fields from an entity) on an abstract entity type, which is not allowed.
  Cause:
  
  Abstract Entity Type: The entity you are trying to project from is defined as an abstract entity in the OData model. Abstract entities are meant to be base types that cannot be instantiated directly and are usually used for inheritance.
  Projection Usage: The projection syntax (e.g., using $$projection in your OData query) is being applied to an abstract entity, which is not supported by the OData service.
  
  Solution:
  
  Check Entity Definition: Review the definition of the entity in your OData model. If it is marked as abstract, you cannot use projections directly on it. Instead, you should use a concrete entity that inherits from the abstract entity.
  Use Concrete Entities: Modify your query to target a concrete entity that extends the abstract entity. This way, you can apply projections on the concrete entity instead.
  Adjust OData Query: If you are using a query that includes projections, ensure that it is directed at a non-abstract entity. For example, if you have an abstract entity BaseEntity and a concrete entity ConcreteEntity, your query should be directed at ConcreteEntity.
  Review OData Service Implementation: If you are developing or maintaining the OData service, ensure that the service is correctly set up to handle projections only on concrete entities.
  
  Related Information:
  
  OData Protocol: Understanding the OData protocol and how it handles entity types, especially abstract vs. concrete entities, can help in troubleshooting similar issues.
  SAP Gateway: Familiarize yourself with the SAP Gateway and how it processes OData requests, including entity definitions and service implementations.
  SAP Documentation: Refer to the official SAP documentation for OData services and entity modeling for more detailed information on abstract entities and projections.
  
  By following these steps, you should be able to resolve the error and successfully implement the desired functionality in your SAP OData service.