What kind of data structure is needed to parse JSON to itab? - json

Question

I want to parse a json string into an abap internal table, for example, this one
{
"apiVersion": "1.0",
"data": {
"location": "Dresden",
"temperature": "7",
"skytext": "Light rain",
"humidity": "96",
"wind": "7.31 km/h",
"date": "02-14-2017",
"day": "Tuesday"
}
}
I want to use the method cl_fdt_json=>json_to_data and put the values and keys into a table like this
types: begin of map,
key type string,
value type string,
end of map.
data json_data type standard table of map.
But, unfortunately, it does not work like that. Does anyone have experience with this kind of problem? I don't have access to all the documentation because this is my sample task for a hirement to SAP and this is the last part of the "puzzle" ;) It is hard for me to find the solution.
Thank you!!!
EDIT: accordingly to vwegerts answer I tried the following. This is a little bit different to what i originally wanted to do, but it would also be ok)
DATA cl_oops TYPE REF TO cx_dynamic_check.
DATA(text) = result.
TYPES: BEGIN OF ty_structure,
skytext TYPE string,
location type string,
temperature type string,
humidity type string,
wind type string,
date type string,
day type string,
END OF ty_structure.
DATA : wa_structure TYPE ty_structure.
TRY.
CALL TRANSFORMATION id
SOURCE XML text
RESULT data = wa_structure.
message wa_structure-skytext type 'I'.
CATCH cx_transformation_error INTO cl_oops.
WRITE cl_oops->get_longtext( ).
ENDTRY.
but it still doesnt work. when i check the value of wa_structure-skytext it is unfortunatly empty. i cannot find the mistake. does anyone have an idea?

Answer 1

Rather than use the FDT class (which might not be available on all systems), you might want to take a look at the well-documented capabilities of the ABAP runtime system itself. This example program might be the way to go for you. You would essentially provide a Simple Transformation that would map the JSON XML structure to your data structure, instantiate a sXML JSON reader and then pass that as source to CALL TRANSFORMATION.

Answer 2

Besides #vwegert recommendation to use the SAP documented json transformations, you could check the open source alternatives. This one looks promising.

Answer 3

{"apiVersion":"1.0", "data":{ "location":"Dresden", "temperature":"7", "skytext":"Light rain", "humidity":"96", "wind":"7.31 km/h", "date":"02-14-2017", "day":"Tuesday" } }
The corresponding structure in ABAP would be:
"The nested data table
Types: Begin of ty_data,
location TYPE string,
temperature TYPE string,
skytext TYPE string,
etc.
End of ty_data,
ty_t_data TYPE STANDARD TABLE OF ty_data WITH NON-UNIQUE DEFAULT KEY INITIAL SIZE 0.
"the whole json structure
Types: Begin of ty_json,
apiversion TYPE string,
data TYPE ty_t_data,
End of ty_json.
DATA: ls_data TYPE ty_json.
Now you have to find a proper JSON deserializer, which handles nested tables.
Most deserializer expect a table input, so you have to add '['... ']' at the end of your JSON string and define lt_data TYPE STANDARD TABLE OF ty_json.

Answer 4

You can do it like that via SAP JSON-XML reader:
CLASS lcl_json DEFINITION.
PUBLIC SECTION.
TYPES: BEGIN OF map,
key TYPE string,
value TYPE string,
END OF map,
tt_map TYPE STANDARD TABLE OF map WITH DEFAULT KEY.
CLASS-METHODS: parse IMPORTING iv_json TYPE string
RETURNING VALUE(rv_map) TYPE tt_map.
ENDCLASS.
CLASS lcl_json IMPLEMENTATION.
METHOD parse.
DATA(o_reader) = cl_sxml_string_reader=>create( cl_abap_codepage=>convert_to( iv_json ) ).
TRY.
DATA(o_node) = o_reader->read_next_node( ).
WHILE o_node IS BOUND.
CASE o_node->type.
WHEN if_sxml_node=>co_nt_element_open.
DATA(op) = CAST if_sxml_open_element( o_node ).
LOOP AT op->get_attributes( ) ASSIGNING FIELD-SYMBOL(<a>).
APPEND VALUE #( key = <a>->get_value( ) ) TO rv_map ASSIGNING FIELD-SYMBOL(<json>).
ENDLOOP.
WHEN if_sxml_node=>co_nt_value.
DATA(val) = CAST if_sxml_value_node( o_node ).
<json>-value = val->get_value( ).
WHEN OTHERS.
ENDCASE.
o_node = o_reader->read_next_node( ).
ENDWHILE.
CATCH cx_root INTO DATA(e_txt).
RAISE EXCEPTION TYPE cx_sxml_parse_error EXPORTING error_text = e_txt->get_text( ).
ENDTRY.
ENDMETHOD.
ENDCLASS.
START-OF-SELECTION.
DATA(json_string) = ` {"apiVersion":"1.0", ` &&
` "data":{ "location":"Dresden", "temperature":"7",` &&
` "skytext":"Light rain", "humidity":"96", "wind":"7.31 km/h", "date":"02-14-2017", "day":"Tuesday" } } `.
TRY.
DATA(it_map) = lcl_json=>parse( json_string ).
CATCH cx_root INTO DATA(e_txt).
" do handling
ENDTRY.