How to convert JSON to ABAP Internal Table data

06/13/2020

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Dear SAPLearners, in this blog post we will learn how to convert JSON to ABAP internal table or structure.

In my current S/4 HANA project we have a requirement to call a 3rd party REST API like AWS REST API services and store the data in a custom database table and further display the data in an ALV report.

The 3rd party REST API is returning the data in JSON format, so we have to convert to an internal table format so we can store it in a custom table.

Let’s get started.

Prerequisite

Install SSL Certificate

Convert JSON to ABAP

For demo purpose I am using SWAPI-The Star Wars API which is available publicly, the response of the API call is in JSON format.

You can follow this and apply the logic to any REST API service provided by Azure, GCP and AWS.

Here is the JSON data we are converting.

Below is sample ABAP code to convert JSON data into ABAP internal table.

TYPES: BEGIN OF ty_final,
         name           TYPE string,
         model          TYPE string,
         manufacturer   TYPE string,
         starship_class TYPE string,
       END OF ty_final.

DATA: lv_code          TYPE i,
      lv_url           TYPE string,
      li_client        TYPE REF TO if_http_client,
      lt_errors        TYPE TABLE OF string,
      lv_error_message TYPE string,
      lv_json_data     TYPE string,
      lr_data          TYPE REF TO data,
      ls_final         TYPE ty_final,
      lt_final         TYPE TABLE OF ty_final.

FIELD-SYMBOLS:
  <data>        TYPE data,
  <results>     TYPE any,
  <structure>   TYPE any,
  <table>       TYPE ANY TABLE,
  <field>       TYPE any,
  <field_value> TYPE data.


lv_url = 'https://swapi.dev/api/starships'.

cl_http_client=>create_by_url(
  EXPORTING
    url           = lv_url
    ssl_id        = 'ANONYM'
  IMPORTING
    client        = li_client ).

li_client->send( ).
li_client->receive(
  EXCEPTIONS
    http_communication_failure = 1
    http_invalid_state         = 2
    http_processing_failed     = 3
    OTHERS                     = 4 ).
IF sy-subrc <> 0.
  WRITE: / 'Error Number', sy-subrc, /.
  MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
  li_client->get_last_error(
    IMPORTING
      message = lv_error_message ).
  SPLIT lv_error_message AT cl_abap_char_utilities=>newline INTO TABLE lt_errors.
  LOOP AT lt_errors INTO lv_error_message.
    WRITE: / lv_error_message.
  ENDLOOP.
  RETURN.
ENDIF.

li_client->response->get_status(
  IMPORTING
    code = lv_code ).
IF lv_code = 200.
  WRITE: / lv_url, ': OK', icon_checked AS ICON.
  WRITE: /.

  lv_json_data = li_client->response->get_cdata( ).

  CALL METHOD /ui2/cl_json=>deserialize
    EXPORTING
      json         = lv_json_data
      pretty_name  = /ui2/cl_json=>pretty_mode-user
      assoc_arrays = abap_true
    CHANGING
      data         = lr_data.

  IF lr_data IS BOUND.
    ASSIGN lr_data->* TO <data>.
    ASSIGN COMPONENT `RESULTS` OF STRUCTURE <data> TO <results>.
    ASSIGN <results>->* TO <table>.

    LOOP AT <table> ASSIGNING <structure>.
      ASSIGN <structure>->* TO <data>.

      ASSIGN COMPONENT `NAME` OF STRUCTURE <data> TO <field>.
      IF <field> IS ASSIGNED.
        lr_data = <field>.
        ASSIGN lr_data->* TO <field_value>.
        ls_final-name = <field_value>.
      ENDIF.
      UNASSIGN: <field>, <field_value>.

      ASSIGN COMPONENT `MODEL` OF STRUCTURE <data> TO <field>.
      IF <field> IS ASSIGNED.
        lr_data = <field>.
        ASSIGN lr_data->* TO <field_value>.
        ls_final-model = <field_value>.
      ENDIF.
      UNASSIGN: <field>, <field_value>.

      ASSIGN COMPONENT `MANUFACTURER` OF STRUCTURE <data> TO <field>.
      IF <field> IS ASSIGNED.
        lr_data = <field>.
        ASSIGN lr_data->* TO <field_value>.
        ls_final-manufacturer = <field_value>.
      ENDIF.
      UNASSIGN: <field>, <field_value>.

      ASSIGN COMPONENT `STARSHIP_CLASS` OF STRUCTURE <data> TO <field>.
      IF <field> IS ASSIGNED.
        lr_data = <field>.
        ASSIGN lr_data->* TO <field_value>.
        ls_final-starship_class = <field_value>.
      ENDIF.
      UNASSIGN: <field>, <field_value>.

      APPEND ls_final TO lt_final.
      CLEAR ls_final.
    ENDLOOP.
  ENDIF.

  cl_demo_output=>write_data( lt_final ).
  cl_demo_output=>display( ).
ENDIF.

If you run the program, the json data will be displayed in an internal table

In the above code I used DESERIALIZE( ) method of class /UI2/CL_JSON to deserialize JSON data. Along with this method there are two other ways in which you can deserialize JSON data, they are