Technical Articles
How to perform a deep update with SAP Gateway OData V4 framework?
Introduction
The SAP Gateway OData V4 framework does not support to perform a deep update.
This is also true for the OData V2 framework. And as a result also RAP based services do currently not support deep updates.
However today I learned about the need of such a support for an integration scenario where the consuming OData (or rather REST) client only supported updates using a payload which required a deep update support.
Since this support was only needed for a few API’s and since the requirement was not a generic support for deep updates I came to the conclusion (after some internal discussions) that a custom http handler would be an option in this case.
When checking the ICF node used by the SAP Gateway OData V4 framework we see that this uses the http handler class /IWBEP/CL_OD_ICF_HANDLER.
Custom http handler
For my POC I copied the class to a transportable class in the customer namespace and added a check in the code that checks
- if the incoming request is a PUT request and
- if the URL of the incoming request matches the URL of the entity that is to be updated
The copied http handler class ZIWBEP_CL_OD_ICF_HANDLER is registered in SICF for the OData V4 node.
Method if_http_extension~handle_request
The important method is the method if_http_extension~handle_request.
In this method I have added a check for the http method that is used by the incoming request.
DATA(http_method_used) = to_lower( server->request->get_method( ) ).
IF lv_uri_path_after_handler_org = '/iwbep/v4_sample/default/iwbep/v4_gw_sample_basic/0001/salesorderlist(''0500000001'')' AND
http_method_used = 'put'.
If this check is not successful the standard implementation is called.
METHOD if_http_extension~handle_request.
* URL segments:
* foo://example.com:8042/over/there?name=ferret
* \_/ \______________/\_________/ \_________/
* | | | |
* scheme authority path query
DATA:
lo_request_handler TYPE REF TO if_http_extension,
"!" Path part of the URL behind the segment where the ICF handler (this class) is registered - AFTER alias resolution
"! <br/>E.g. '/iwbep/tea/default/iwbep/tea_busi/0001/TEAMS'
lv_uri_path_after_handler TYPE string,
"!" Path part of the URL behind the segment where the ICF handler (this class) is registered - BEFORE alias resolution
lv_uri_path_after_handler_org TYPE string,
"! Path part of the URL up to segment where the ICF handler (this class) is registered - AFTER alias resolution
"! <br/>This must be '/sap/opu/odata4'
lv_uri_path_up_to_handler TYPE string.
lv_uri_path_up_to_handler = to_lower( server->request->get_header_field( if_http_header_fields_sap=>script_name_expanded ) ).
lv_uri_path_after_handler = to_lower( server->request->get_header_field( if_http_header_fields_sap=>path_info_expanded ) ).
lv_uri_path_after_handler_org = to_lower( server->request->get_header_field( if_http_header_fields_sap=>path_info ) ).
" This handler must only be registered under the ICF node '/sap/opu/odata4'
ASSERT lv_uri_path_up_to_handler = /iwbep/cl_v4_url_util=>gc_icf_path_odata4.
" An alias must not point behind an ICF node after node '/sap/opu/odata4'
ASSERT lv_uri_path_after_handler = lv_uri_path_after_handler_org.
DATA(http_method_used) = to_lower( server->request->get_method( ) ).
IF lv_uri_path_after_handler_org = '/iwbep/v4_sample/default/iwbep/v4_gw_sample_basic/0001/salesorderlist(''0500000001'')' AND
http_method_used = 'put'.
DATA(payload) = server->request->get_cdata( ).
"do something with payload
server->response->set_cdata(
EXPORTING
data = cl_demo_output=>get( 'Hello World' )
).
server->response->set_status(
EXPORTING
code = if_web_http_status=>ok
reason = 'success_deep_update'
).
ELSE.
IF lv_uri_path_after_handler = /iwbep/cl_v4_url_util=>gc_icf_path_async_monitor
OR lv_uri_path_after_handler CP /iwbep/cl_v4_url_util=>gc_icf_path_async_monitor && '*'.
lo_request_handler = NEW /iwbep/cl_od_http_req_hand_arm( ).
ELSE.
lo_request_handler = NEW /iwbep/cl_od_http_req_handler( ).
ENDIF.
lo_request_handler->handle_request( server ).
ENDIF.
ENDMETHOD.
METHOD if_oauth2_consumer~provide_tadir_key_for_request.
CONSTANTS:
lc_program_id_r3tr TYPE pgmid VALUE 'R3TR',
lc_object_type_service_group TYPE trobjtype VALUE 'G4BA'.
DATA:
lv_uri_path_after_handler TYPE string, " E.g. '/iwbep/tea/default/iwbep/tea_busi/0001/TEAMS'
lv_service_group_id TYPE /iwbep/v4_med_group_id.
lv_uri_path_after_handler = i_http_request->get_header_field( if_http_header_fields_sap=>path_info_expanded ).
/iwbep/cl_v4_url_util=>parse_path_after_handler(
EXPORTING
iv_uri = lv_uri_path_after_handler
IMPORTING
ev_service_group_id = lv_service_group_id ).
e_tadir_key-obj_name = lv_service_group_id.
e_tadir_key-object = lc_object_type_service_group.
e_tadir_key-pgmid = lc_program_id_r3tr.
ENDMETHOD.
ENDCLASS.
Result
When running a deep update request we can see in the debug mode that one is able to retrieve the payload of the request.
So it will be possible to parse the JSON file and to extract the data so that one can perform a custom implementation for the deep update.
The result in the SAP Gateway Client then looks as follows:
As a reason “success_deep_update” is shown alongside with the response “Hello World” as it has been set in the coding of our custom http handler class.
server->response->set_cdata(
EXPORTING
data = cl_demo_output=>get( 'Hello World' )
).
server->response->set_status(
EXPORTING
code = if_web_http_status=>ok
reason = 'success_deep_update'
).
Hi Andre and sorry for my ignorance, but what is a "deep update"?
Reading your blog, I guess it has nothing to to with a code or system upgrade, but rather how to access resources via OData?
Hi Michael,
your guess is correct.
A deep update request would be a PUT / PATCH operation on an entity .../salesorder(45) and in the payload alongside with the salesorder information you would be able to pass data for the items that are part of this salesorder.
Right now you would have to send several PUT / PATCH requests for each items that is to be maintained and for the sales order header data.
Currenty it is only possible to create such objects using a so called deep insert in one request.
I will work further on this post and show how one can use an action as a workaround as well since actions in V4 accept an arbritrary payload so that the deep structure could be passed as a payload on action.
This would eliminate the need of changing the http handler which is not nice and clean.
Kind regards,
Andre
Thanks Andre for this explanation and keep going on posting 😉
Hi Andre,
I might be missing something here. How this is different from the requests we handle in Deep_Entity method of dpc_ext class ?
BR,
Nitish
It is different because it is
a) a deep update and not a deep_insert
b) V4 and not V2 which you use when implementing DPC_EXT in SEGW.
Kind regards,
Andre