Working with Event Parameters

Define a CDS abstract entity (suggested name: Z##_A_Event) with a single element of type abp_root_entity_name (suggested name: origin).

1. Create a new data definition (suggested name: Z##_A_Event) that defines a CDS abstract entity. Assign it to your own package and use the same transport request as before.

   1. In the Project Explorer view, open the context menu for the Data Definitions folder that is located under the Core Data Services folder in your package ZS4D437_##.

   2. From the context menu, select New Data Definition.

   3. Enter the name of the new data definition and a description and choose Next.

   4. Select the same transport request as before and choose Next.

   5. From the list of templates, choose Abstract Entity (creation)→defineAbstractEntityWithParameters and choose Finish.

2. In the editor that opens, remove the with parameters addition, because the abstract entity does not need parameters.

   1. Adjust the code as follows:

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      define abstract entity Z##_A_Event
      {

3. In the element list, replace placeholder element_name with origin and placeholder element_type with abp_root_entity_name.

   1. Adjust the code as follows:

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      define abstract entity Z##_A_Event
      {
        origin : abp_root_entity_name;
      }

4. Activate the abstract entity.

   1. Press Ctrl + F3 to activate the development object.

Add a parameter to your event and use the abstract entity Z##_A_Event as parameter type. Adjust the RAISE ENTITY EVENT statement and populate the parameter with the name of your root entity in upper case (Z##_R_TRAVEL). Finally, remove the hard-coded value for Origin from the event handler implementation.

1. Edit your behavior definition on data model level Z##_R_TRAVEL and locate the definition of the TravelCreated event.

   1. For example, you can press Ctrl + F to invoke a search dialog where you search for EVENT.

2. Add an event parameter that is typed with your abstract entity.

   1. Adjust the code as follows:

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      event TravelCreated parameter Z##_A_Event;

3. Activate the behavior definition and use the Where-Used List to navigate to the RAISE ENTITY EVENT statement for the event.

   1. Press Ctrl + F3 to activate the development object.

   2. In the EVENT statement, place the cursor on the event name and press Ctrl + Shift + G.

   3. On the Get Where-Used List dialog that appears, choose Finish.

   4. From the Where-Used List in the Search view below the editor, choose ZBP_##_R_TRAVEL (Class)→Local Class Implementation→RAISE ENTITY EVENT Z##_R_Travel~TravelCreated.

4. Adjust the RAISE ENTITY EVENT statement. Make sure the data object after the FROM addition contains not only the key values (columns AgencyId and TravelId), but also the name of your root view entity in upper case in the origin column.

   Note

   Either define a data object of type TABLE FOR EVENT Z##_R_Travel~TravelCreated and fill it in a LOOP-ENDLOOP structure before the RAISE ENTITY EVENT statement, or use a VALUE expression after FROM with a FOR iteration inside.

   1. Adjust the code as follows:

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      IF create-travel IS NOT INITIAL.    
        DATA event_in TYPE TABLE FOR EVENT Z##_R_Travel~TravelCreated.
       
        LOOP AT create-travel ASSIGNING FIELD-SYMBOL(<new_travel>).
          APPEND VALUE #( AgencyId = <new_travel>-AgencyId
                          TravelId = <new_travel>-TravelId
                          origin   = 'Z##_R_TRAVEL' )
            TO event_in.
        ENDLOOP.
      
        RAISE ENTITY EVENT Z##_R_Travel~TravelCreated
          FROM event_in.
      ENDIF.

      Alternative implementation using a VALUE expression:

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      IF create-travel IS NOT INITIAL.
        RAISE ENTITY EVENT Z##_R_Travel~TravelCreated
          FROM VALUE #( FOR <new_travel> IN create-travel
                          (
                            AgencyId = <new_travel>-AgencyId
                            TravelId = <new_travel>-TravelId
                            origin   = 'Z##_R_TRAVEL'
                          )
                      ).
      ENDIF.

5. Activate the behavior implementation and use the Where-Used List for the event to navigate to the handler method.

   1. Press Ctrl + F3 to activate the development object.

   2. If the Where-Used List for the event is no longer visible, place the cursor on the event name in the RAISE ENTITY EVENT statement and press Ctrl + Shift + G.

   3. On the Get Where-Used List dialog that appears, choose Finish.

   4. From the Where-Used List in the Search view below the editor, choose ZCL_##_HANDLER (Class)→Local Class Implementation→FOR Travel~TravelCreated.

6. In the MODIFY ENTITIES statement, remove the data object after WITH and replace it with a CORRESPONDING expression, having the event parameter as input.

   Note

   This is sufficient because the event parameter now contains the origin component.

   1. Adjust the code as follows:

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      MODIFY ENTITIES OF /LRN/437_I_TravelLog
        ENTITY TravelLog
          CREATE AUTO FILL CID
          FIELDS ( AgencyID TravelID Origin )
          WITH CORRESPONDING #( new_travels ).

7. Remove or comment the superfluous data declaration and the loop.

   1. Select the DATA statement, the ENDLOOP statement, and all code rows between them and press Ctrl + < to insert a comment sign at the beginning of each selected code row.

8. Activate the handler class and retest the event handling.

   1. Press Ctrl + F3 to activate the development object.

   2. Reopen the preview of your OData UI service and choose Create to create a new flight travel.

   3. Enter all mandatory fields for the flight travel and choose Create.

   4. Take note of the values displayed in the Agency ID field and the Travel ID field.

   5. Open the preview for OData UI service /LRN/UI_437_TRAVELLOG_O2.

   6. Choose Go. (If there are too many entries, enter Z##_R_TRAVEL under Root Entity Name and choose Go again.)

      Result

      You see an entry that corresponds to the flight travel that you created.