RESTfull webservice in ABAP returning JSON

[diogo_awaihara]

It is very simple to create a webservice using only ABAP, thanks to naresh.bammidi that showed us the way!

:smile:

Basically, we start by creating a new class in SE24 implementing interface IF_HTTP_EXTENSION.

Then, we just implement the method handle_request.

The trick is to concatenate everything in a single string, using the JSON style, and set the content type by using the method set_header_field.

Check my sample code bellow:

METHOD if_http_extension~handle_request.

     CONSTANTS: c_object_start TYPE c VALUE '{',

                c_object_end   TYPE c VALUE '}'.

     DATA: lv_path_info      TYPE string,

           lv_request_method TYPE string,

           lv_response_data  TYPE string.

     DATA: it_inputparams TYPE tihttpnvp,

           ls_inputparams TYPE LINE OF tihttpnvp.

     DATA: lv_ebeln TYPE ekpo-ebeln,

           lv_ebelp TYPE ekpo-ebelp,

           lv_matnr TYPE ekpo-matnr.

     FIELD-SYMBOLS <fs_param> TYPE LINE OF tihttpnvp.

     "Get request info

     lv_path_info = server->request->get_header_field( name = '~path_info' ).

     lv_request_method = server->request->get_header_field( name = '~request_method' ).

     "Only GET is allowed

     IF lv_request_method NE 'GET'.

       CALL METHOD server->response->set_header_field( name = 'Allow' value = 'GET' ).

       CALL METHOD server->response->set_status( code = '405' reason = 'Method not allowed' ).

       EXIT.

     ENDIF.

     "Get GET parameters

     CALL METHOD server->request->get_form_fields

       CHANGING

         fields = it_inputparams.

     UNASSIGN <fs_param>.

     LOOP AT it_inputparams ASSIGNING <fs_param>.

       TRANSLATE <fs_param>-name TO UPPER CASE.

     ENDLOOP.

     CLEAR: lv_ebeln, ls_inputparams.

     READ TABLE it_inputparams INTO ls_inputparams WITH KEY name = 'PO'.

     lv_ebeln = ls_inputparams-value.

     CLEAR ls_inputparams.

     "Empty parameter

     IF lv_ebeln IS INITIAL.

       CALL METHOD server->response->set_status( code = '404' reason = 'Empty parameters are not allowed' ).

       CALL METHOD server->response->set_cdata( data = 'There are one or more missing parameters' ).

       EXIT.

     ENDIF.

     "Start of response data

     lv_response_data = c_object_start.

     "Add element: PO

     lv_response_data = | { lv_response_data } "PO":" { lv_ebeln }", |.

     "Add array: ITEMS

     lv_response_data = | { lv_response_data } "ITEMS":[ |.

     "Add items

     SELECT ebelp matnr

       INTO (lv_ebelp, lv_matnr)

       FROM ekpo

       WHERE ebeln = lv_ebeln.

       lv_response_data = | { lv_response_data } { c_object_start } "NITEM":"{ lv_ebelp }","MATERIAL":"{ lv_matnr }" { c_object_end },|.

     ENDSELECT.

     IF sy-subrc = 0.

       SHIFT lv_response_data RIGHT DELETING TRAILING space.

     ENDIF.

     "End of array

     lv_response_data = | { lv_response_data } ] |.

     "End of response data

     lv_response_data = | { lv_response_data } { c_object_end } |.

     "Set JSON Content-Type

     CALL METHOD server->response->set_header_field( name = 'Content-Type' value = 'application/json; charset=UTF-8' ).

     "Set Response Data

     CALL METHOD server->response->set_cdata( data = lv_response_data ).

ENDMETHOD.

After that just publish it in SICF, into Handler list and test it.

I tested it in SoapUI 5.2.1.

Reference doc: http://scn.sap.com/docs/DOC-46463