Introduction

In this blog I will explain creation of simple SAP NW GW OData service which will implement Create, Read, Update, Delete, Query and Function Import operations.

Just to make it very simple, I will just have single entity and entity set. Here I will perform these operations on Z table. In real scenarios, you will use BAPIs. RFCs to perform these operations.

I recommend to read below documents and SAP documentation for deep understanding.

How to Develop a Gateway Service using Code based Implementation by Andre Fischer

How to Develop Query Options for an OData Service Using Code-Based Implementationby Andre Fischer

How to Write an OData Channel Gateway Service. Part 2 – The Runtime Data Provider Class

SAP Help – SAP NetWeaver Gateway Foundation Developer Guide – SAP NetWeaver Gateway Foundation (SAP_GWFND) – SAP Library

Code Snippet – 3.2 Data Provider Class (DPC) – SAP NetWeaver Gateway Foundation (SAP_GWFND) – SAP Library

Scenario

We have User information table as ZUSERINFO containing below fields

Now let’s create OData service which will insert, read, delete, update and query this table along with one custom operation (UsersByCountry) as function import.

From an ABAPer perspective, This is what meant by OData operations.

We can correlate Entity Set as Table Type, Internal table and Entity to work area, structure!

Procedure

Let’s go to transaction SEGW and create project as ZUSERINFO.

Now right click on Data Model and Import –> DDIC Structure option, it will display popup window. Provide DDIC structure name. In this case table name ZUSERINFO. It will propose field and key mapping as well as object name which will be your entity name.

We will ignore MANDT as key field and also overwrite object name. I want my field names in upper camel case format so I will change it accordingly.  Let’s call entity type as User. It will look as below. Press enter.

finally our entity type User will look as below.

Now let’s create Entity Set as UserCollection (or UserSet or Users). You can refer Creating High-Quality OData Services – SAP NetWeaver Gateway Foundation (SAP_GWFND) – SAP Library

I will go with UserCollection as my entity set name.

Right click folder name Entity Sets and click create. Provide entity set name as UserCollection and Entity Type name as User. It will display as below.

Now let’s generate runtime artifacts. Click on generate runtime objects button. It will display popup as below. Keep the default class names as-is and click on enter button.

On successful generation, you will see this kind of message log and generated artifacts. 4 classes will get generated. 2 for Data provider and 2 for Model provider.

Now register your service under service Maintenance folder. Click on Register button. Keep default values as-is and hit enter button.

On successful registration, click Maintain button. This will open service catalog window along with option to call Gateway Client. Click on Gateway Client button to test the service. (you can also call transaction /IWFND/GW_CLIENT to open SAP NW Gateway client)

Append $metatda to base service URL and press execute button. If everything is fine then you will HTTP Response as below. Metadata provides information such as Entity type, key property, properties and Entity Set name.

So far we just defined single entity type and entity set. Now it’s time to code CRUDQ and function import methods.

Coding

There is no specific order to implement these methods but it is always good to 1st implement query and read operation as for Create and Update, you will need request data which you will get if you already have query/read implemented.

1) Query Operation

First we will start implementing query operation. Before that, I will add one record in my ZUSERINFO table as

Now open Runtime artifacts folder and right click on Class ZCL_ZUSERINFO_DPC_EXT and select Go to ABAP Workbench option. Select edit mode and redefine method USERCOLLECTION_GET_ENTITYSET.

In the simplest form, this is what minimal coding will look like in GET_ENTITYSET method.

METHOD usercollection_get_entityset.

  DATA: lt_userinfo TYPE TABLE OF zuserinfo,

        ls_userinfo LIKE LINE OF lt_userinfo,

        ls_entity   LIKE LINE OF et_entityset.

*Get data from ZUSERINFO table

  SELECT * FROM zuserinfo INTO TABLE lt_userinfo.

*Fill ET_ENTITYSET

  LOOP AT lt_userinfo INTO  ls_userinfo .

    ls_entity-userid    = ls_userinfo-userid.

    ls_entity-firstname = ls_userinfo-firstname.

    ls_entity-lastname  = ls_userinfo-lastname.

    ls_entity-email     = ls_userinfo-email.

    ls_entity-phone     = ls_userinfo-phone.

    ls_entity-country  = ls_userinfo-country.

    APPEND ls_entity TO et_entityset.

  ENDLOOP.

ENDMETHOD.

We are selecting all data from table ZUSERINFO and appending the result to exporting parameter ET_ENTITYSET.

Now you can go to GW client transaction and execute URI  /sap/opu/odata/sap/ZUSERINFO_SRV/UserCollection which will display one record which we already added into Z table.

Observe the method signature. put external breakpoint in method and execute query. You will find important information in method parameters in debugging mode.

Below table will provide brief explanation of method parameters, alternative approach to get the value of those method parameters. Last column specifies if we need to code to implement query operation.

Here IO_TECH_REQUEST_CONTEXT refers to /IWBEP/IF_MGW_REQ_ENTITYSET

2) Read Operation

Now let’s implement GET_ENTITY method. Go to method USERCOLLECTION_GET_ENTITY and redefine it. Below is the minimal code that we need to have in this method.

We need to read the key values passed from query URI and then fill the export parameter ER_ENTITY.

METHOD usercollection_get_entity.

DATA:  ls_key_tab   TYPE /iwbep/s_mgw_name_value_pair,

        lv_userid   TYPE zuserinfo-userid,

        ls_userinfo TYPE  zuserinfo.

*Get the key property values

READ TABLE it_key_tab WITH KEY name = 'UserID' INTO ls_key_tab.

  lv_userid = ls_key_tab-value.

*Get the single record from ZUSERINFO and fill ER_ENTITY

SELECT SINGLE * FROM zuserinfo INTO ls_userinfo WHERE userid = lv_userid.

  IF sy-subrc = 0.

    er_entity-userid    = ls_userinfo-userid.

    er_entity-firstname = ls_userinfo-firstname.

    er_entity-lastname  = ls_userinfo-lastname.

    er_entity-email     = ls_userinfo-email.

    er_entity-phone     = ls_userinfo-phone.

    er_entity-country   = ls_userinfo-country.

  ENDIF.

ENDMETHOD.

Here IO_TECH_REQUEST_CONTEXT refers to /IWBEP/IF_MGW_REQ_ENTITY

Also note that you cannot use system query options else you will get an error as System query options ‘$orderby,$skip,$top,$skiptoken,$inlinecount,’ are not allowed in the requested URI

3) Create Operation

Now we will focus on create operation by redefining method USERCOLLECTION_CREATE_ENTITY. Below is the code that will perform POST operation.

Here we are reading the request data and then filling the exporting parameter ER_ENTITY.

METHOD usercollection_create_entity.

  DATA: ls_request_input_data TYPE zcl_zuserinfo_mpc=>ts_user,

        ls_userinfo TYPE zuserinfo.

* Read Request Data

  io_data_provider->read_entry_data( IMPORTING es_data = ls_request_input_data ).

* Fill workarea to be inserted

  ls_userinfo-userid   = ls_request_input_data-userid.

  ls_userinfo-firstname = ls_request_input_data-firstname.

  ls_userinfo-lastname = ls_request_input_data-lastname.

  ls_userinfo-email    = ls_request_input_data-email.

  ls_userinfo-phone    = ls_request_input_data-phone.

  ls_userinfo-country  = ls_request_input_data-country.

* Insert Data in table ZUSERINFO

  INSERT zuserinfo FROM ls_userinfo.

  IF sy-subrc = 0.

    er_entity = ls_request_input_data. "Fill Exporting parameter ER_ENTITY

  ENDIF.

ENDMETHOD.

To test POST operation, 1^st execute GET operation and then press Use as Request button which will copy the response to request window and then select operation POST and execute.

In case you execute GET operation i.e. GET_ENITITYSET and then try to perform POST operation then you will get below kind of error. Hence make sure that you execute GET to read single entity i.e. GET_ENTITY operation and then perform POST.

So correct steps are,

1) Execute GET to read single entity /sap/opu/odata/sap/ZUSERINFO_SRV/UserCollection(‘Test’)

2) Click Use as Request button

3) Update your request properties.

4) Select HTTP method as POST

5) Query as /sap/opu/odata/sap/ZUSERINFO_SRV/UserCollection and execute

Here IO_TECH_REQUEST_CONTEXT refers to /IWBEP/IF_MGW_REQ_ENTITY_C

In case of Create operation, you cannot use system query options else you will get an error as

The Data Services Request contains SystemQueryOptions that are not allowed for this Request Type

This error message comes from method PROCESS_ENTITY_SET (/IWCOR/CL_DS_PROC_DISPATCHER). Just in case if you are curious and want to know 😉

4) Update Operation

Now we will implement update operation by redefining method USERCOLLECTION_UPDATE_ENTITY. We need to put below code in this method.

METHOD usercollection_update_entity.

  DATA:  ls_request_input_data TYPE zcl_zuserinfo_mpc=>ts_user,

         ls_key_tab            TYPE /iwbep/s_mgw_name_value_pair,

         lv_userid             TYPE zuserinfo-userid,

         ls_userinfo           TYPE zuserinfo.

* Get key values

  READ TABLE it_key_tab WITH KEY name = 'UserID' INTO ls_key_tab.

  lv_userid = ls_key_tab-value.

  IF lv_userid IS NOT INITIAL.

* Read request data

    io_data_provider->read_entry_data( IMPORTING es_data = ls_request_input_data ).

* Update fields of table ZUSERINFO

    UPDATE zuserinfo SET firstname = ls_request_input_data-firstname

                         lastname  = ls_request_input_data-lastname

                         email     = ls_request_input_data-email

                         phone     = ls_request_input_data-phone

                         country   = ls_request_input_data-country

                         WHERE userid  = lv_userid.

    IF sy-subrc = 0.

      er_entity = ls_request_input_data. "Fill exporting parameter ER_ENTITY

    ENDIF.

  ENDIF.

ENDMETHOD.

Here also first we need to execute GET operation to read the entity and then copy the response to request using Use as Request button and execute PUT operation after editing required data. Successful HTTP response will look as below with status code as 204.

Here IO_TECH_REQUEST_CONTEXT refers to /IWBEP/IF_MGW_REQ_ENTITY_U

5) Delete Operation

To implement Delete operation, you need to execute DELETE HTTP method for particular key. Below is the code for method USERCOLLECTION_DELETE_ENTITY.

Here we are reading key value of the record to be deleted and executing Delete statement.

METHOD usercollection_delete_entity.

  DATA:  ls_key_tab TYPE /iwbep/s_mgw_name_value_pair,

         lv_userid TYPE zuserinfo-userid.

* Read key values

  READ  TABLE it_key_tab INTO ls_key_tab WITH KEY name = 'UserID'.

  lv_userid = ls_key_tab-value.

  IF lv_userid IS NOT INITIAL.

* Delete record from table ZUSERINFO

    DELETE FROM zuserinfo WHERE userid = lv_userid.

  ENDIF.

ENDMETHOD.

On successful record deletion, you will see HTTP response code as 204.

Here IO_TECH_REQUEST_CONTEXT refers to /IWBEP/IF_MGW_REQ_ENTITY_D

6) Function Import 

As per SAP documentation, Function Imports – SAP NetWeaver Gateway Foundation (SAP_GWFND) – SAP Library

The Open Data Protocol (OData) includes standard CRUD (Create, Retrieve, Update, and Delete) operations that map to the HTTP methods POST, GET, PUT/MERGE, and DELETE.

In addition, OData supports further service operations (function imports) that can be invoked by the HTTP methods GET or POST for anything that cannot be mapped to the standard CRUD operations. You can implement such additional service operations in the Service Builder by creating function imports within your data model.

For example, you could create function imports for the following custom operations:

• Confirm Work Item
• Check Flight Availability

While it is simple to create new function imports to invoke custom operations, if the operation you want to use can be invoked using a standard CRUD operation, you should not create a function import. That is, you should only create function imports for custom operations that cannot be invoked using a standard operation.

In simple terms, if an operation cannot fit into CRUD scenario then you can perform it by function import.

Suppose our ZUSERINFO table looks like below,

And we want to get users by specific country then we can implement function import. Let’s call our function import as UsersByCountry!

Right click on Data model and create function import. Provide proper name. Again refer Creating High-Quality OData Services – SAP NetWeaver Gateway Foundation (SAP_GWFND) – SAP Library

Provide required details such as mentioned below. Remember here we want to return collection of users and hence we selected Return cardinality as 0..n with return entity set and HTTP method type as GET.

Now click on Function Import parameters and create import parameters as shown below. In this case we just want to pass value of country and hence we will have one parameter as Country.

Finally save project, check project consistency and generate runtime objects. To check if everything is fine, in GW client execute service metadata URL as /sap/opu/odata/sap/ZUSERINFO_SRV/$metadata which should show you function import definition in metadata as below,

Now we will implement function import operation. Go to DPC_EXT class and redefine method /IWBEP/IF_MGW_APPL_SRV_RUNTIME~EXECUTE_ACTION.

Put below code to implement function import.

METHOD /iwbep/if_mgw_appl_srv_runtime~execute_action.

  DATA: ls_parameter  TYPE /iwbep/s_mgw_name_value_pair,

        lv_country    TYPE string,

        lt_userinfo   TYPE TABLE OF zuserinfo,

        ls_userinfo   TYPE zuserinfo,

        ls_entity     TYPE  zcl_zuserinfo_mpc=>ts_user,

        lt_entityset  TYPE zcl_zuserinfo_mpc=>tt_user.

  IF iv_action_name = 'UsersByCountry'. " Check what action is being requested

    IF it_parameter IS NOT INITIAL.

* Read Function import parameter value

      READ TABLE it_parameter INTO ls_parameter WITH KEY name = 'Country'.

      IF sy-subrc = 0.

        lv_country = ls_parameter-value.

      ENDIF.

      IF lv_country IS NOT INITIAL.

        SELECT  * FROM zuserinfo INTO TABLE lt_userinfo WHERE country = lv_country.

        LOOP AT lt_userinfo INTO  ls_userinfo .

          ls_entity-userid   = ls_userinfo-userid.

          ls_entity-firstname = ls_userinfo-firstname.

          ls_entity-lastname = ls_userinfo-lastname.

          ls_entity-email    = ls_userinfo-email.

          ls_entity-phone    = ls_userinfo-phone.

          ls_entity-country  = ls_userinfo-country.

          APPEND ls_entity TO lt_entityset.

        ENDLOOP.

* Call methos copy_data_to_ref and export entity set data

        copy_data_to_ref( EXPORTING is_data = lt_entityset

                CHANGING cr_data = er_data ).

      ENDIF.

    ENDIF.

  ENDIF.

ENDMETHOD.

To test function import we need to query as /sap/opu/odata/sap/ZUSERINFO_SRV/UsersByCountry?Country=’US’

If there are multiple parameters then it will be separated by an ampersand (&).

Here IO_TECH_REQUEST_CONTEXT refers to /IWBEP/IF_MGW_REQ_FUNC_IMPORT

Closing Remarks

This is very simple example of an OData service. In real case scenarios, you will have multiple entities, relationship, association and navigation between them but when it comes to coding in DPC_EXT class methods, you will find above explanation of each method, parameters and alternative way to get the parameter values useful.

I hope you enjoyed reading this blog and now ready to develop your OData service! I request you to put comments/suggestions. Please feel free if you have any different thought to improve any part of this blog as well.

[Update – 9/25/2014] I have posted new blog which focuses more on association/navigation and data provider $expand. You can access it at Let’s code association/navigation and data provider expand in OData service!

Happy Learning & Coding 🙂 🙂 🙂