Tuesday, 25 July 2017

Cube view and query view Part-9

In previous eight steps all we focus on is transactional stuff. This time let’s touch some analytics stuff.

Let’s first create a most simple database table in ABAP backend:

ABAP CDS, ABAP Development

Then create a simple cube view:

@EndUserText.label: 'Jerry cube view'
@Analytics.dataCategory: #CUBE
@AbapCatalog.sqlViewName: 'zprdcube'
define view Z_C_Prod_Cube as select from zprd_query{
   key zprd_query.prod_id,
  @DefaultAggregation: #MAX

This cube view has only three fields: prod_id, prod_text and quantity.

Then create a query view on top of the cube view:

@EndUserText.label: 'Jerry query verification'
@Analytics.query: true
@AbapCatalog.sqlViewName: 'zprdquery'
@OData.publish: true
define view Z_C_Product as select from Z_C_Prod_Cube {
  key Z_C_Prod_Cube.prod_id,
  @DefaultAggregation: #MAX

Since I use @OData.publish: true, a new OData service is automatically generated when this query view is activated.

We have already discussed how this generation is achieved in this blog: My CDS view self study tutorial – Part 4 how does annotation @OData.publish work.

Once activation is finished, we can do some testing. In ABAP backend I have two entries in the table:

ABAP CDS, ABAP Development

So once we perform the read operation via generated OData service: /sap/opu/odata/sap/Z_C_Product_cds/Z_C_PRODUCT

we can see these two entries are returned in OData response automatically:

ABAP CDS, ABAP Development

Let’s do some further research to find out how these two entries are retrieved from backend.

We have CDS view name as Z_C_Product and the generated OData service based on it has name Z_C_Product_CDS.

Like normal CDS view activation with annotation @OData.publish: true, there is also a new ABAP class @OData.publish: true automatically generated, which has only one method redefined: GET_QUERY_NAME. In this method, a constant attribute is returned.

The content of this attribute: ‘2Czprdquery’.

The biggest difference compared with a normal CDS view activation is: when a query view is activated, the generated OData service data provider class has CL_NAT_ODATA_MODEL_ABS as its super class, giving you a hint that all data retrieved based on this query view will be handled by analytics framework.

ABAP CDS, ABAP Development

While for a normal CDS view, the DPC class has super class CL_SADL_GTK_EXPOSURE_MPC, which means the data access in this case is done by SADL framework.

ABAP CDS, ABAP Development

In order to figure out the detail data access logic implementation by analytics framework, I write the following report to simulate the OData call:

REPORT zcds_get_query_view_data.
DATA(lo_tool) = NEW cl_nat_generic_dpc( ).
DATA(lo_context) = NEW /iwbep/cl_mgw_context( ).
DATA: l_r_rs_gw_columns TYPE REF TO cl_abap_tabledescr,
      l_t_rs_gw_columns TYPE REF TO data,
      lo_request        TYPE REF TO /iwbep/cl_mgw_request,
      lo_detail         TYPE REF TO /iwbep/if_mgw_core_srv_runtime=>ty_s_mgw_request_context,
      ls_detail         TYPE  /iwbep/if_mgw_core_srv_runtime=>ty_s_mgw_request_context,
      lt_header         TYPE tihttpnvp,
      lt_filter         TYPE /iwbep/t_mgw_select_option,
      lt_order          TYPE /iwbep/t_mgw_sorting_order,
      ls_page           TYPE /iwbep/s_mgw_paging,
      ls_header         TYPE LINE OF tihttpnvp.
    <l_t_rs_gw>       TYPE        table.
lo_context->/iwbep/if_mgw_context~set_parameter( iv_name  = /iwbep/if_mgw_context=>gc_param_isn
     iv_value = 'Z_C_PRODUCT_CDS' ).
lo_context->/iwbep/if_mgw_context~set_parameter(  iv_name  = /iwbep/if_mgw_context=>gc_param_isv
        iv_value = '0001' ).
lo_tool->/iwbep/if_mgw_core_srv_runtime~set_context( lo_context ).
CREATE DATA lo_detail.
lo_request = NEW /iwbep/cl_mgw_request( ir_request_details = lo_detail it_headers = lt_header ).
DATA(lo_rt) = NEW cl_eq_bics_gw_rt( i_query          = '2Czprdquery'
                                    i_servicetype_oq = abap_true ).
    e_t_column_description = DATA(l_t_query_struc) ) .
l_r_rs_gw_columns = cl_eq_bics_gw_dt=>build_rs_structure( l_t_query_struc ).
CREATE DATA l_t_rs_gw_columns TYPE HANDLE l_r_rs_gw_columns.
ASSIGN l_t_rs_gw_columns->* TO <l_t_rs_gw>.
ls_detail-technical_request-service_name = 'Z_C_PRODUCT_CDS'.
ls_detail-technical_request-service_version = '0001'.
ls_detail-technical_request-source_entity_type =  ls_detail-technical_request-target_entity_type
= 'Z_C_PRODUCTType'.
ls_detail-technical_request-source_entity_set = ls_detail-technical_request-target_entity_set
= 'Z_C_PRODUCTTypeCollection'.
ls_header-name = 'dummy'.
APPEND ls_header TO ls_detail-technical_request-request_header.
CALL METHOD lo_tool->/iwbep/if_mgw_core_srv_runtime~read_entityset(
    iv_entity_name           = 'Z_C_PRODUCTType'
    iv_source_name           = 'Z_C_PRODUCTType'
    is_paging                = ls_page
    it_order                 = lt_order
    it_filter_select_options = lt_filter
    is_request_details       = ls_detail
    cr_entityset             = l_t_rs_gw_columns
    ct_headers               = lt_header
ASSIGN l_t_rs_gw_columns->* TO <l_t_rs_gw>.
WRITE: 'lines of data: ', lines( <l_t_rs_gw> ).

With SAT trace I can easily locate the exact location of code where the data retrieve is done:

ABAP CDS, ABAP Development

ABAP CDS, ABAP Development

In this line the DB cursor is opened with generated SQL statement:

ABAP CDS, ABAP Development

ABAP CDS, ABAP Development

Mystery Revealed!

ABAP CDS, ABAP Development

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