Friday, 15 October 2021 16:20

A new generation of CDS views: how to migrate your CDS views to CDS view entities

Written by Andrea Schlotthauer
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Source https://blogs.sap.com/2021/10/16/a-new-generation-of-cds-views-how-to-migrate-your-cds-views-to-cds-view-entities/
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With ABAP release 7.55, a new type of CDS view has been released: the CDS view entity. CDS view entities are an improvement over the “classic” CDS DDIC-based views.

For details, see the blog post about CDS view entities.

New migration tool available

Now, a new migration tool is available that automates many steps of a migration from a CDS DDIC-based view to a CDS view entity. But that’s not the only helper to facilitate a migration. The following support has been released:

This blog post first provides some general information about migration and then gives details on each helper tool.

General considerations

View entities are by design incompatible with DDIC-based views.
The advantages of CDS view entities can only be realized based on incompatible changes to the concepts and implementation of existing CDS views. The most prominent example is the deletion of the CDS-managed DDIC view, that means, the ABAP Dictionary SQL view that is attached to each DDIC-based view. This DDIC SQL view is deleted during a migration to a CDS view entity and all scenarios which rely on the DDIC SQL view no longer work.

No automatic migration will take place.
During  migration, semantics of a view might change. Because of this, each developer needs to decide whether they want to migrate their views.

Reverse migration
To reverse-migrate from view entity back to DDIC-based view just open a support ticket on BC-DWB-DIC.

Program for migration analysis

Since ABAP On-Premise Release 7.55, an ABAP program is available that evaluates whether a migration from a CDS DDIC-based view to a CDS view entity is possible:

RUTDDLS_MIGRATION_CANDIDATES

You can select DDLS sources to be analyzed directly by name or indirectly by original system, person responsible, package, and so on.

As a result, all DDLS sources specified are classified into one of the following categories (column Overall Status):

Moreover, details on the sources of the errors are provided. Currently, the following aspects are checked for each migration candidate:

  • Entity and DDLS name of the migration candidate must be identical. Otherwise, migration is not possible.
  • The decimal shift function DECIMAL_SHIFT cannot be used in a migration candidate, since it is not supported in CDS view entities. CDS view entities offer the following functions instead:
    • CURR_TO_DECFLOAT_AMOUNT
    • GET_NUMERIC_VALUE
  • The data source of the migration candidate cannot be a DDIC external view, since DDIC external views are
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