Introduction

In my earlier blog Let’s code CRUDQ and Function Import operations in OData service! we understood the basic operation performed in OData service.


In this blog I will explain creation of simple SAP Gateway OData service having association and navigation between entities. Also we will see how to implement it through code based approach and finally conclude with implantation of GET_EXPANDED_ENTITYSET and GET_EXPANDED_ENTITY

invoked by $expand.

Note – Steps mentioned in this blog are performed in SAP Gateway System SP08 (Embedded Architecture)

Let’s see what is meant by association and navigation property.

Associations define the relationship between two or more Entity Types (for example, Employee WorksFor Department). Instances of associations are grouped in Association Sets.

Navigation Properties are special properties on Entity Types which are bound to a specific association and can be used to refer to associations of an entity.

Finally, all instance containers (Entity Sets and Association Sets) are grouped in an Entity Container.

Reference – Overview | Open Data Protocol

Also let’s understand the difference between association/navigation and $expand. In short, it is as below,

Association/Navigation Give me associated (dependent) entity/entities using Navigation property http://services.odata.org/OData/OData.svc/Categories(1)/Products?$format=json
$expand

Give me associated (dependent) entity/entities + Principal entity/entities

using Navigation property

http://services.odata.org/OData/OData.svc/Categories(1)?$expand=Products&$format=json

you can also refer this nice blog Implementing  Expand Entity/Entity Set by Srikanth Gajula

Scenario

We will read Sales order, items and product data from Enterprise Procurement Model (EPM). This is the pictorial representation of sales order, items and product with their association.

/wp-content/uploads/2014/09/dpe_540239.jpg

We will have 3 entities as displayed in below EDM diagram.

/wp-content/uploads/2014/09/dpe1_540240.jpg

SalesOrder will be associated with SalesOrderItem and SalesOrderItem with Product.

Principle Entity Dependent Entity Navigation Property Cardinality
SalesOrder SalesOrderItem OrderToItems 1:N
SalesOrderItem Product ItemToProduct 1:1

We will use below BAPIs to get the Sales Order, Items and Product data in DPC_EXT class methods.

  • BAPI_EPM_SO_GET_LIST
  • BAPI_EPM_SO_GET_DETAIL
  • BAPI_EPM_PRODUCT_GET_DETAIL

We will code for association/navigation and data provider expand scenario and will also understand the framework expand.

Before that just look at difference between Data provider expand and framework expand

Framework Expand Data Provider Expand
Formerly called as generic expand Formerly called as basic expand
Requires no implementation effort Requires implementation effort
As this is handled by framework, same logic may be called multiple times in loop resulting in poor performance In some cases, this provides better performance depending on how the code is implemented

Reference – Expand in Framework and Data Provider – SAP NetWeaver Gateway – SAP Library

Procedure


Create entity SalesOrder by importing DDIC structure as shown below. Please note that Entity set will be created by default if the check box “Create Default Entity Set” is checked.

/wp-content/uploads/2014/09/dpe2_540241.jpg

Repeat the process for entities SalesOrderItem and Product. End result will be as displayed below.

/wp-content/uploads/2014/09/dpe3_540245.jpg

Now let’s create association, navigation etc. By using Create Association wizard, it is just 3 steps as displayed below. This will create Navigation property, Association set etc.

Create association between entities SalesOrder and SalesOrderItem with navigation property as OrderToItems.

/wp-content/uploads/2014/09/dpe4_540246.jpg

On similar lines, create association between entities SalesOrderItem and Product with navigation property as ItemToProduct.

/wp-content/uploads/2014/09/dpe5_540247.jpg

Please note that we do not have referential constraints created between SalesOrderItem and Product.

The final OData modeling will look like as below,

/wp-content/uploads/2014/09/dpe6_540248.jpg

Coding

In this section, we will redefine methods in DPC_EXT class. Please note that code provided in this blog is in simplest form. You may need to consider proper error handling and other best practices while writing the code.

Association/Navigation

First we will implement logic in method SALESORDERSET_GET_ENTITYSET by redefining it.

We will use below execution URI in Gateway Client (Transaction /IWFND/GW_CLIENT) to check the response payload.

/sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet

METHOD salesorderset_get_entityset.

  DATA: lt_salesorder TYPE TABLE OF bapi_epm_so_header,

         ls_salesorder LIKE LINE OF lt_salesorder,

         ls_entity   LIKE LINE OF et_entityset,

         l_max_rows TYPE bapi_epm_max_rows.

  l_max_rows-bapimaxrow = ’10’.

  CALL FUNCTION ‘BAPI_EPM_SO_GET_LIST’

    EXPORTING

      max_rows    = l_max_rows

    TABLES

      soheaderdata = lt_salesorder.

*Fill ET_ENTITYSET

  LOOP AT lt_salesorder INTO  ls_salesorder .

    MOVE-CORRESPONDING ls_salesorder TO ls_entity.

    APPEND ls_entity TO et_entityset.

  ENDLOOP.

ENDMETHOD.

Redefine method SALESORDERSET_GET_ENTITY as below and then execute with below URI

/sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000009’)

METHOD salesorderset_get_entity.

  DATA: ls_salesorder TYPE bapi_epm_so_header,

        ls_key_tab    TYPE /iwbep/s_mgw_name_value_pair,

        lv_soid       TYPE bapi_epm_so_id.

*Get the key property values

  READ TABLE it_key_tab WITH KEY name = ‘SoId’ INTO ls_key_tab.

  lv_soid = ls_key_tab-value.

  CALL FUNCTION ‘CONVERSION_EXIT_ALPHA_INPUT’

    EXPORTING

      input = lv_soid

    IMPORTING

      output = lv_soid.

  CALL FUNCTION ‘BAPI_EPM_SO_GET_DETAIL’

    EXPORTING

      so_id     = lv_soid

    IMPORTING

      headerdata = ls_salesorder.

*Fill ER_ENTITY

  MOVE-CORRESPONDING ls_salesorder TO er_entity.

ENDMETHOD.

Redefine method SALESORDERITEMSE_GET_ENTITYSET as below with URI

/sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000008’)/OrderToItems

METHOD salesorderitemse_get_entityset.

  DATA: ls_salesorder TYPE bapi_epm_so_header,

        lt_itemdata   TYPE TABLE OF bapi_epm_so_item,

        ls_itemdata   TYPE  bapi_epm_so_item,

        ls_entity     LIKE LINE OF et_entityset.

  DATA:  ls_key_tab  TYPE /iwbep/s_mgw_name_value_pair,

          lv_soid    TYPE bapi_epm_so_id.

*Get the key property values

  READ TABLE it_key_tab WITH KEY name = ‘SoId’ INTO ls_key_tab.

  lv_soid = ls_key_tab-value.

  CALL FUNCTION ‘CONVERSION_EXIT_ALPHA_INPUT’

    EXPORTING

      input = lv_soid

    IMPORTING

      output = lv_soid.

  CALL FUNCTION ‘BAPI_EPM_SO_GET_DETAIL’

    EXPORTING

      so_id     = lv_soid

    IMPORTING

      headerdata = ls_salesorder

    TABLES

      itemdata  = lt_itemdata.

  LOOP AT lt_itemdata INTO ls_itemdata.

    MOVE-CORRESPONDING ls_itemdata TO ls_entity  .

    APPEND ls_entity  TO et_entityset.

  ENDLOOP.

ENDMETHOD.

Notice that we used navigation property OrderToItems to get the associated entities.

Framework expand

By executing below URI, it will call framework expand by default.

/sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet?$expand=OrderToItems

This calls method SALESORDERSET_GET_ENTITYSET and SALESORDERITEMSE_GET_ENTITYSET in loop.

Check the values in header name sapgw-statistics for URI /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet?$expand=OrderToItems&sap-statistics=true

This will give you performance statistics for OData request. For more information, refer Some new features in SAP NW Gateway 2.0 SP08

/wp-content/uploads/2014/09/dpe7_540249.jpg

If we execute URI /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000009’)?$expand=OrderToItems

It will call method SALESORDERSET_GET_ENTITY and SALESORDERITEMSE_GET_ENTITYSET.

For below URI to work

/sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000000′)/OrderToItems(SoId=’0500000000′,SoItemPos=’0000000010’)

We need to implement logic with navigation property keys.

Alternatively we can read as /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderItemSet(SoId=’0500000000′,SoItemPos=’0000000010′)

Let’s implement SALESORDERITEMSE_GET_ENTITY so that we can read data for above URI as

METHOD salesorderitemse_get_entity.

  DATA: ls_salesorder TYPE bapi_epm_so_header.

  DATA:  ls_key_tab   TYPE /iwbep/s_mgw_name_value_pair,

          lv_soid  TYPE bapi_epm_so_id,

          lv_soitempos TYPE snwd_so_item_pos,

          lt_itemdata TYPE TABLE OF bapi_epm_so_item,

         ls_itemdata TYPE  bapi_epm_so_item.

*Get the key property values

  READ TABLE it_key_tab WITH KEY name = ‘SoId’ INTO ls_key_tab.

  lv_soid = ls_key_tab-value.

  READ TABLE it_key_tab WITH KEY name = ‘SoItemPos’ INTO ls_key_tab.

  lv_soitempos = ls_key_tab-value.

  CALL FUNCTION ‘CONVERSION_EXIT_ALPHA_INPUT’

    EXPORTING

      input = lv_soid

    IMPORTING

      output = lv_soid.

  CALL FUNCTION ‘CONVERSION_EXIT_ALPHA_INPUT’

    EXPORTING

      input = lv_soitempos

    IMPORTING

      output = lv_soitempos.

*Get data from BAPI

  CALL FUNCTION ‘BAPI_EPM_SO_GET_DETAIL’

    EXPORTING

      so_id     = lv_soid

    IMPORTING

      headerdata = ls_salesorder

    TABLES

      itemdata  = lt_itemdata.

  READ TABLE  lt_itemdata INTO  ls_itemdata WITH KEY so_id = lv_soid

                                                      so_item_pos = lv_soitempos.

  IF sy-subrc = 0.

    MOVE-CORRESPONDING ls_itemdata TO er_entity.

  ENDIF.

ENDMETHOD.

Use of Navigation Path to read navigation keys

To read the data for below URI, we need to implement logic as below in method PRODUCTSET_GET_ENTITY

Execution URI – /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000001′)/OrderToItems(SoId=’500000001′,SoItemPos=’0000000010’)/ItemToProduct

METHOD productset_get_entity.

  DATA: ls_salesorder TYPE bapi_epm_so_header.

  DATA:  ls_key_tab   TYPE /iwbep/s_mgw_name_value_pair,

         lv_soid  TYPE bapi_epm_so_id,

         lv_soitempos TYPE snwd_so_item_pos,

         lt_itemdata TYPE TABLE OF bapi_epm_so_item,

         ls_itemdata TYPE  bapi_epm_so_item.

  DATA: ls_navigation    TYPE /iwbep/s_mgw_navigation_path,

        lv_property                 TYPE string.

  DATA: lv_product_id TYPE bapi_epm_product_id,

        lv_product_header TYPE bapi_epm_product_header.

  IF iv_source_name = iv_entity_name.

*Get the key property values

    READ TABLE it_key_tab WITH KEY name = ‘ProductId’ INTO ls_key_tab.

    IF sy-subrc = 0.

* MOVE-CORRESPONDING ls_itemdata to er_entity.

      lv_product_id = ls_key_tab-value.

      CALL FUNCTION ‘BAPI_EPM_PRODUCT_GET_DETAIL’

        EXPORTING

          product_id = lv_product_id

        IMPORTING

          headerdata = lv_product_header.

      MOVE-CORRESPONDING lv_product_header TO er_entity.

    ENDIF.

  ELSE.

    IF it_navigation_path IS NOT INITIAL.

      READ TABLE it_navigation_path INTO ls_navigation INDEX 1.

      IF sy-subrc EQ 0.

        CASE ls_navigation-nav_prop.

          WHEN ‘OrderToItems’.

            LOOP AT ls_navigation-key_tab INTO ls_key_tab.

              CASE ls_key_tab-name.

                WHEN ‘SoId’.

                  lv_soid = ls_key_tab-value.

                WHEN ‘SoItemPos’.

                  lv_soitempos = ls_key_tab-value.

                WHEN OTHERS.

              ENDCASE.

            ENDLOOP.

        ENDCASE.

      ENDIF.

    ENDIF.

    CALL FUNCTION ‘CONVERSION_EXIT_ALPHA_INPUT’

      EXPORTING

        input = lv_soid

      IMPORTING

        output = lv_soid.

    CALL FUNCTION ‘CONVERSION_EXIT_ALPHA_INPUT’

      EXPORTING

        input = lv_soitempos

      IMPORTING

        output = lv_soitempos.

*Get data from BAPI_EPM_SO_GET_DETAIL

    CALL FUNCTION ‘BAPI_EPM_SO_GET_DETAIL’

      EXPORTING

        so_id     = lv_soid

      IMPORTING

        headerdata = ls_salesorder

      TABLES

        itemdata  = lt_itemdata.

*Fill ER_ENTITY

    READ TABLE  lt_itemdata INTO  ls_itemdata WITH KEY so_id = lv_soid

                                                        so_item_pos = lv_soitempos.

    IF sy-subrc = 0.

      lv_product_id-product_id = ls_itemdata-product_id.

      CALL FUNCTION ‘BAPI_EPM_PRODUCT_GET_DETAIL’

        EXPORTING

          product_id = lv_product_id

        IMPORTING

          headerdata = lv_product_header.

      MOVE-CORRESPONDING lv_product_header TO er_entity.

    ENDIF.

  ENDIF.

ENDMETHOD.

Also note that we can read product directly using URI /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/ProductSet(‘HT-1030’)

Now try with this URI /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000000’)?$expand=OrderToItems/ItemToProduct

Product details will not filled as in the navigation keys are empty because we do not have referential constraint.

Also try with /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderItemSet(SoId=’0500000000′,SoItemPos=’0000000020′)/ItemToProduct and check why it is not working.

Additionally you can query as

/sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000000’)/$links/OrderToItems

/sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000009’)/$links/OrderToItems/$count

Data Provider Expand

In this section, we will see how to implement data provider expand by redefining GET_EXPANDED_ENTITYSET and GET_EXPANDED_ENTITY.

Implementing GET_EXPANDED_ENTITYSET

Let’s redefine GET_EXPANDED_ENTITYSET. With redefinition (just blank code) execute again the URI /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet?$expand=OrderToItems

You will not get any response as you need to implement the code yourself.

One of the important point while implementing logic is Data declaration! Based on level till which you want to expand, you need to define your internal table having nested structure or table type.

In below code, we want to expand Sales Order and its items. Hence the expand technical clause will be ORDERTOITEMS.

METHOD /iwbep/if_mgw_appl_srv_runtime~get_expanded_entityset.

  DATABEGIN OF t_expand_so.

  INCLUDE             TYPE zcl_ztest_dp_expand_mpc_ext=>ts_salesorder.

  DATA: ordertoitems  TYPE zcl_ztest_dp_expand_mpc_ext=>tt_salesorderitem,

       END OF t_expand_so.

  DATA: lt_expand_so   LIKE  TABLE OF t_expand_so,

        ls_expand_so   LIKE t_expand_so,

        ls_item        TYPE zcl_ztest_dp_expand_mpc_ext=>ts_salesorderitem.

  DATA: lt_salesorder  TYPE TABLE OF bapi_epm_so_header,

        ls_salesorder LIKE LINE OF lt_salesorder,

        lt_itemdata   TYPE TABLE OF bapi_epm_so_item,

        ls_itemdata   TYPE  bapi_epm_so_item,

        l_max_rows    TYPE bapi_epm_max_rows.

  CONSTANTS: lc_expand_tech_clause TYPE string VALUE ‘ORDERTOITEMS’.

* Read Sales Order and Item data

  l_max_rows-bapimaxrow = ’10’.

  CALL FUNCTION ‘BAPI_EPM_SO_GET_LIST’

    EXPORTING

      max_rows    = l_max_rows

    TABLES

      soheaderdata = lt_salesorder

      soitemdata  = lt_itemdata.

* Data processing logic

  LOOP AT lt_salesorder INTO ls_salesorder.

    MOVE-CORRESPONDING ls_salesorder TO ls_expand_so  .

    LOOP AT lt_itemdata INTO ls_itemdata WHERE so_id = ls_salesorder-so_id .

      MOVE-CORRESPONDING ls_itemdata TO ls_item  .

      APPEND ls_item  TO ls_expand_so-ordertoitems.

      CLEAR: ls_item.

    ENDLOOP.

    APPEND ls_expand_so  TO lt_expand_so.

    CLEAR: ls_expand_so.

  ENDLOOP.

* Fill EE_ENTITYSET

  copy_data_to_ref(

    EXPORTING

      is_data = lt_expand_so

    CHANGING

      cr_data = er_entityset ).

* Insert Navigation property into ET_EXPANDED_TECH_CLAUSES

  INSERT lc_expand_tech_clause INTO TABLE et_expanded_tech_clauses.

ENDMETHOD.

Query with URI /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet?$expand=OrderToItems&sap-statistics=true to check the runtime statistics and compare the values with before implementing data provider expand.

/wp-content/uploads/2014/09/dpe8_540250.jpg

Now we will try to expand to one level more i.e. we will expand sales order, its items and product of each item. In this case the expand technical clause will be ORDERTOITEMS/ITEMTOPRODUCT.

Below is the code we need to put to achieve the desired result.

METHOD /iwbep/if_mgw_appl_srv_runtime~get_expanded_entityset.

  DATABEGIN OF t_orderitems.

  INCLUDE              TYPE  zcl_ztest_dp_expand_mpc_ext=>ts_salesorderitem.

  DATA: itemtoproduct TYPE  zcl_ztest_dp_expand_mpc_ext=>ts_product,

        END OF t_orderitems.

  DATABEGIN OF t_expand_so.

  INCLUDE             TYPE zcl_ztest_dp_expand_mpc_ext=>ts_salesorder.

  DATA: ordertoitems  LIKE TABLE OF t_orderitems,

       END OF t_expand_so.

  DATA: lt_expand_so   LIKE  TABLE OF t_expand_so,

        ls_expand_so   LIKE t_expand_so,

        ls_item        LIKE t_orderitems.

  DATA: lt_salesorder  TYPE TABLE OF bapi_epm_so_header,

        ls_salesorder LIKE LINE OF lt_salesorder,

        lt_itemdata   TYPE TABLE OF bapi_epm_so_item,

        ls_itemdata   TYPE  bapi_epm_so_item,

        l_max_rows    TYPE bapi_epm_max_rows.

  DATA: lv_product_id TYPE bapi_epm_product_id,

         ls_product_header TYPE bapi_epm_product_header.

  CONSTANTS: lc_expand_tech_clause  TYPE string VALUE ‘ORDERTOITEMS/ITEMTOPRODUCT’.

* Read Sales Order and Item data

  l_max_rows-bapimaxrow = ’10’.

  CALL FUNCTION ‘BAPI_EPM_SO_GET_LIST’

    EXPORTING

      max_rows    = l_max_rows

    TABLES

      soheaderdata = lt_salesorder

      soitemdata  = lt_itemdata.

* Data processing logic

  LOOP AT lt_salesorder INTO ls_salesorder.

    MOVE-CORRESPONDING ls_salesorder TO ls_expand_so  .

    LOOP AT lt_itemdata INTO ls_itemdata WHERE so_id = ls_salesorder-so_id .

      MOVE-CORRESPONDING ls_itemdata TO ls_item  .

      lv_product_id = ls_itemdata-product_id.

      CALL FUNCTION ‘BAPI_EPM_PRODUCT_GET_DETAIL’

        EXPORTING

          product_id = lv_product_id

        IMPORTING

          headerdata = ls_product_header.

      MOVE-CORRESPONDING ls_product_header TO ls_item-itemtoproduct.

      APPEND ls_item  TO ls_expand_so-ordertoitems.

      CLEAR: ls_item.

    ENDLOOP.

    APPEND ls_expand_so  TO lt_expand_so.

    CLEAR: ls_expand_so, lv_product_id.

  ENDLOOP.

* Fill EE_ENTITYSET

  copy_data_to_ref(

    EXPORTING

      is_data = lt_expand_so

    CHANGING

      cr_data = er_entityset ).

* Insert Navigation property into ET_EXPANDED_TECH_CLAUSES

  INSERT lc_expand_tech_clause INTO TABLE et_expanded_tech_clauses.

ENDMETHOD.

Please note that we need to insert complete expand clause in et_expanded_tech_clauses

Implementing GET_EXPANDED_ENTITY

Let’s implement GET_EXPANDED_ENTITY.

Below is the query to execute and code to for implementation.


/sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000005’)?$expand=OrderToItems/ItemToProduct

METHOD /iwbep/if_mgw_appl_srv_runtime~get_expanded_entity.

  DATABEGIN OF t_orderitems.

  INCLUDE              TYPE  zcl_ztest_dp_expand_mpc_ext=>ts_salesorderitem.

  DATA: itemtoproduct TYPE  zcl_ztest_dp_expand_mpc_ext=>ts_product,

        END OF t_orderitems.

  DATABEGIN OF t_expand_so.

  INCLUDE             TYPE zcl_ztest_dp_expand_mpc_ext=>ts_salesorder.

  DATA: ordertoitems  LIKE TABLE OF t_orderitems,

       END OF t_expand_so.

  DATA: ls_expand_so   LIKE t_expand_so,

        ls_item LIKE t_orderitems.

  DATA:  ls_salesorder TYPE bapi_epm_so_header,

         lt_itemdata   TYPE TABLE OF bapi_epm_so_item,

         ls_itemdata   TYPE  bapi_epm_so_item.

  DATA:  ls_key_tab   TYPE /iwbep/s_mgw_name_value_pair,

          lv_soid  TYPE bapi_epm_so_id.

  DATA: lv_product_id     TYPE bapi_epm_product_id,

        ls_product_header TYPE bapi_epm_product_header.

  CONSTANTS: lc_expand_tech_clause  TYPE string VALUE ‘ORDERTOITEMS/ITEMTOPRODUCT’.

*Get the key property values and Read Sales Order and Item data

  READ TABLE it_key_tab WITH KEY name = ‘SoId’ INTO ls_key_tab.

  lv_soid = ls_key_tab-value.

  CALL FUNCTION ‘CONVERSION_EXIT_ALPHA_INPUT’

    EXPORTING

      input = lv_soid

    IMPORTING

      output = lv_soid.

  CALL FUNCTION ‘BAPI_EPM_SO_GET_DETAIL’

    EXPORTING

      so_id     = lv_soid

    IMPORTING

      headerdata = ls_salesorder

    TABLES

      itemdata  = lt_itemdata.

* Data processing logic

  MOVE-CORRESPONDING ls_salesorder TO ls_expand_so  .

  LOOP AT lt_itemdata INTO ls_itemdata WHERE so_id = ls_salesorder-so_id .

    MOVE-CORRESPONDING ls_itemdata TO ls_item  .

    lv_product_id = ls_itemdata-product_id.

    CALL FUNCTION ‘BAPI_EPM_PRODUCT_GET_DETAIL’

      EXPORTING

        product_id = lv_product_id

      IMPORTING

        headerdata = ls_product_header.

    MOVE-CORRESPONDING ls_product_header TO ls_item-itemtoproduct.

    APPEND ls_item  TO ls_expand_so-ordertoitems.

  ENDLOOP.

* Fill ER_ENTITY

  copy_data_to_ref(

    EXPORTING

      is_data = ls_expand_so

    CHANGING

      cr_data = er_entity ).

* Insert Navigation property into ET_EXPANDED_TECH_CLAUSES

  INSERT lc_expand_tech_clause INTO TABLE et_expanded_tech_clauses.

ENDMETHOD.

Closing Remarks

Important points to be considered while coding for association/navigation and data provider $expand,

  • Use of navigation path and navigation key. Entities can be directly accessed or via navigation property. Code for both scenario using navigation path and navigation keys.
  • Data declaration of internal tables in case of data provider expand. Understand the relations between entities. while declaring internal table, use navigation property name to address dependent entity structure. It should be same. Check below data declaration.

  DATABEGIN OF t_orderitems.

  INCLUDE              TYPE  zcl_ztest_fw_expand_mpc_ext=>ts_salesorderitem.

  DATA: itemtoproduct TYPE  zcl_ztest_fw_expand_mpc_ext=>ts_product,

        END OF t_orderitems.

  DATABEGIN OF t_expand.

  INCLUDE             TYPE zcl_ztest_fw_expand_mpc_ext=>ts_salesorder.

  DATA: ordertoitems  LIKE TABLE OF t_orderitems,

       END OF t_expand.

  DATA: lt_so   LIKE  TABLE OF t_expand,

        ls_so   LIKE t_expand,

        ls_item LIKE t_orderitems.

  • Parent and its immediate child will be separated using “/” for e.g $expand=OrderToItems/ItemToProduct  if we would have 2nd sibling at order level for e.g Partners of Sales order then we could have navigation property as OrderToPartners with say its child as PartnerToAddress then we need to access it as OrderToPartners/PartnerToAddress. To get the expanded result for both hierarchies, the expand clause will look as $expand=OrderToItems/ItemToProduct,OrderToPartners/PartnerToAddress (separated by “,”)
  • Navigation property separated with “/” will be inserted into expanded technical clause. 2nd hierarchy will be appended in expanded technical clause

        In short, for example mentioned in point 3, it would be,

ls_expanded_clause_items = ‘ORDERTOITEMS/ITEMTOPRODUCT’.

ls_expanded_clause_partners = ‘ORDERTOPARTNERS/PARTNERTOADDRESS’.

APPEND ls_expanded_clause_items TO et_expanded_tech_clauses.

APPEND ls_expanded_clause_partners TO et_expanded_tech_clauses.

        also refer this thread Error with $expand and navigation: Resource not found for the segment ‘NavAtp’

  • whether framework expand or data provider expand provides better result will depends on your scenario. Please notice that with $expand, we are making single call to read the parent and child data but at the same time ensure that the data to be retrieved is not too large.

I hope you enjoyed reading this blog and now will be able to play with association/navigation and data provider $expand!

Please feel free if you have any different thoughts to improve any section of this blog.

Happy Learning & Coding 🙂 🙂 🙂

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32 Comments

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  1. Ashwin Dutt R

    Hello Chandra,

     

    Great and very well explained by

    emphasizing on the scenarios like SalesOrderSet(‘500000005’)?$expand=OrderToItems/ItemToProduct  as we would encounter those kind of scenarios as well

     

    Regards,

    Ashwin

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  2. Ron Sargeant

    Nice work Chandra!

     

    it would be good if you could expand (no pun intended) on the use case for GET_EXPANDED_ENTITYSET and GET_EXPANDED_ENTITY.

    As you have already pointed out, $expand can process an expansion request by looping through the access methods. It would be great to have some clarity of why you would do these methods as an alternative. The SAP Help sort of explains it but it’s not easily understood until you have done a bit of expanding practice.

     

    On a best practice note, I recommend using the technical request object to find keys and navigation values. I’m not 100% sure but the technical request seems to have been added to assist in OData compliance.

    The ‘direct’ keys etc. exposed in the method signatures aren’t quite the same. For one thing technical element names are always in uppercase even if the model element name is not. It’s also easier to pass one technical object reference on to other methods than all of those signature parameters.   

     

    Regards

     

    Ron.

     

    P.S. it’s also nice to see that you didn’t generate your service from the BAPI interfaces – phew!

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    1. Chandrashekhar Mahajan Post author

      Hi Ron,

       

      Thanks for your comments!

       

      Ron Sargeant wrote:

       

       

      it would be good if you could expand (no pun intended) on the use case for GET_EXPANDED_ENTITYSET and GET_EXPANDED_ENTITY.

      As you have already pointed out, $expand can process an expansion request by looping through the access methods. It would be great to have some clarity of why you would do these methods as an alternative. The SAP Help sort of explains it but it’s not easily understood until you have done a bit of expanding practice.

       

       

      Are you referring to framework expand vs data provider expand? I already explained those points with example. Please let me know which use case you want me to explore more.

      Ron Sargeant wrote:

       

      On a best practice note, I recommend using the technical request object to find keys and navigation values. I’m not 100% sure but the technical request seems to have been added to assist in OData compliance.

      The ‘direct’ keys etc. exposed in the method signatures aren’t quite the same. For one thing technical element names are always in uppercase even if the model element name is not. It’s also easier to pass one technical object reference on to other methods than all of those signature parameters. 

       

       

      Yes I agree that using technical request object to get the keys and navigation value, filter value etc is best way. and in my earlier blog, Let’s code CRUDQ and Function Import operations in OData service! I explained it with alternative way to get these values instead of method signature parameter.

       

       

      Regards,

      Chandra

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      1. Ron Sargeant

        Hi Chandra,

         

        I agree that you have shown that there are alternatives, but I wouldn’t say they were explained as a result of just being shown.

         

        Are you referring to framework expand vs data provider expand?”, Yes and no, in my understanding, there is just $expand and how the framework implements the request using it. The consumer can’t ask for a different means of expanding. A properly provided request can expand the feed with no special coding, yet there is an implementation stub for expanding feeds. I think you have shown “if you choose to build an expand method, you can do it like this”, but not explained why.

         

        Regarding use of technical object, it can be confusing for readers to see an author using different coding methods, especially when that difference is not the topic of the article.

         

        In my earlier blogs I used the signature tables because there was no technical context that I recall in earlier versions. Now I always use it and don’t revert to “old style”. I try to keep true to ‘real code’ in examples, even if it takes longer. I use custom code patterns in the editor to make this easier to regulate.

         

        Regards

         

        Ron.

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        1. Yugandhar Reddy

          Hi Chandra,

           

          its a great blog with good details.

          I too have same question as Ron and want to understand difference,why and when we need to go for framework expand vs data provider expand.


          Regards

          Yugandhar Reddy

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      2. Pavan Golesar

        Hello Chandra

                 

        Very good helpful blog.. Its my problem solver in many cases.. i refer to it many times…It touches down almost all major aspects that I feel I are very helpful for learner like me..

         

        Secondly, As mentioned earlier in this blog by you about the

        Coding

         

        In this section, we will redefine methods in DPC_EXT class. Please note that code provided in this blog is in

        simplest form. You may need to consider proper error handling and other best practices while writing the code.

        can you please share any document to refer to for the same.

         

         

        Thanks & Best Regards,

        Pavan Golesar

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  3. Prashanth Kumar

    Hi Chandra,

     

    I have one doubt regarding the asociation, take one example i have one root entity and two or more child entities under the root entity.

     

    But I don’t want to get the parent as well as two or more child details under single roof i.e. by using get_expanded_entity. Instead i need to handle the navigation dynamically means if i want parent and first child details or parent and second child details individually, this can be possible by using the related url. In this case my parent has two separate navigations based on navigation provided in the url i need to respond accordingly.

     

    This can be possible if i will get the navigation name in get_expanded_entity method. But i am not getting the Navigation Name inside the method.

     

    Is there any way to get the navigation name inside the get_expanded_entity, so that i can navigate between parent and 1st child or parent and 2nd child.

     

    Please suggest.

     

    Thanks in advance.

     

    Regards,

    Prashanth Kumar B.

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  4. Anju Jha

    Hi Chandra,

     

    Great blog .

     

    I am facing issue in my Gateway service . My line Item data is displayed 1st and than Header data . My requirement is to get Headerdata 1st . I am using expand statement for expanding line item.

     

    /sap/opu/odata/sap/Z_GW_ECC_PO_SRV/PoHeaderSet/?$expand=PoLineitmSet

     

    Association , Navigation exist

     

    Am i doing something wrong?

     

    Thanks,

    Anju

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  5. haythem Jaidi

    Hi,

     

    Thank you for sharing.

     

    I have a question, as you said adopting framework or Data provider Expand will depend on the performance. So What I need to make it depending on a specific scenario where both logic did exist. For some I want that the Framework handle the Expand and other I want that the GW uses the Data provider implmentation.

     

    How can I achieve that?

     

    Best Regards

    H.JAIDI

    (0) 
  6. Ralf Duckstein

    Hi,

     

    I think there is a mistake in the example above. The cardinality from item to product is not 1:1 but N:1.

     

    1:1 would mean each product is related to exactly one order item.

    N:1 means certain order items may point to the same product.

     

    Of course in both cases an order item always can point only to one product.

     

    So let’s assume you like to select all order items for a given product:

    …/ProductSet(‘12345’)/OrderItems

    Of course when you don’t provide a navigation property for product that links to the order items, then the cardinality is not important. At least so far I noticed no difference then.

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  7. Madhusudhan Mysore Vasudeva

    Hi Chandra,

     

    This is a awesome reference material to start learning SAP Gateway. Thanks a lot and Appreciate your efforts here.

     

    One small q I have to you: Please let me know your comments, whenever you get a chance.

     

    When I am trying to Debug Framework Expand with URI:  /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000000′)/OrderToItems(SoId=’500000000′,SoItemPos=’0000000010’) I am getting error – “Resource not found for segment ‘SalesOrderItem'”. Please find attached snap shot

    For below URI to work

    /sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderSet(‘500000000′)/OrderToItems(SoId=’0500000000′,SoItemPos=’0000000010’)

    We need to implement logic with navigation property keys.

     

    Alternatively we can read as/sap/opu/odata/sap/ZTEST_DP_EXPAND_SRV/SalesOrderItemSet(SoId=’0500000000′,SoItemPos=’0000000010′)

     

    Capture.PNG

     

    But when I use alternative URI which is mentioned just below above URI, that works.

     

    Can we not use URI which we are getting error?

     

    Thanks a lot in advance.

     

    Regards,

    Madhu M V

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  8. Chakram Govindarajan

    Hi Chandra,

     

    Very nice and useful blog. I have bookmarked this link for my future reference.

    I have a question around expand entity. The expand entity works for Get, however when I do a POST, it is not working. How do we create the underlying association entities ?

    How to create association entities during POST. The URI with expand against the parent entity is not allowing me to create the expand entity record. Can you please advise?

     

    Thanks,

    Chakram Govindarajan

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    1. Ram Vellanki

      Hi ChandraSekar Mahajan,

       

         Good article. I have a doubt. for entity SalesOrder DDIC structure bapi_epm_so_header is used. What are the DDIC structures used for Product and SalesOrder.

       

      Thanks

      Ram

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  9. Cristina Rodrigues

    Hello ,

    Can you help me with my question : https://answers.sap.com/questions/52301/how-can-i-consume-service-odata.html

    I follow their tutorials that have helped me to develop many of the applications I’ve ever done

    Thanks very much
    Best Regards
    Cristina Rodrigues

     

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  10. Klaus Reimann

    Hello Chandrashekhar Mahajan, hello dear community,

    first i would like to thank Chandrashekhar Mahajan for the very useful blogpost!

    My question: What about associations for n:m cardinalities like forinstance CRHD-OBJID -> HRP1001-OBJID and HRP1001-OTYPE = ‘A’ -> HRP1001-SOBID and HRP1001-SCLAS = ‘P’ -> PA0002-PERNR ?

    What is best practice in this kind of case?

    An Entity HRP1001 and 2 associations? Or is there another way?

    As the EDM doesn’t support list- or table-types.

    Best regards, Klaus

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