Facts
- Simple Transformations (ST) serialize ABAP to XML and deserialize XML to ABAP.
- JSON-writers of the sXML-Library consume JSON-XML and digest it to JSON.
- The statement CALL TRANSFORMATION handles JSON-sources as JSON-XML implicitly.
Conclusion
The result of an ST that produces JSON-XML can be fed into a JSON writer to produce JSON. The same transformation can be used to deserialize JSON directly (a JSON-reader could be switched in between, but is not necessary).
Example ST producing or consuming JSON-XML
<?sap.transform simple?>
<tt:transform xmlns:tt="http://www.sap.com/transformation-templates">
<tt:root name="CARRIERS"/>
<tt:template>
<array>
<tt:loop ref=".CARRIERS">
<object>
<str name="Carrier-Id">
<tt:value ref="$ref.carrid"/>
</str>
<str name="Carrier">
<tt:value ref="$ref.carrname"/>
</str>
<str name="URL">
<tt:value ref="$ref.url"/>
</str>
</object>
</tt:loop>
</array>
</tt:template>
</tt:transform>
Example ABAP calling ST
CLASS demo DEFINITION.
PUBLIC SECTION.
CLASS-METHODS main.
PRIVATE SECTION.
CLASS-METHODS: display_as_text
IMPORTING json TYPE xstring,
display_as_html
IMPORTING json TYPE xstring.
ENDCLASS.
CLASS demo IMPLEMENTATION.
METHOD main.
"Get some data into an internal table
TYPES: BEGIN OF carrier,
carrid TYPE scarr-carrid,
carrname TYPE scarr-carrname,
url TYPE scarr-url,
END OF carrier.
DATA carriers TYPE TABLE OF carrier.
SELECT carrid carrname url
FROM scarr
INTO CORRESPONDING FIELDS OF TABLE carriers.
"Create JSON-writer and call simple transformation
DATA json_writer TYPE REF TO cl_sxml_string_writer.
DATA writer TYPE REF TO if_sxml_writer.
json_writer = cl_sxml_string_writer=>create( type = if_sxml=>co_xt_json ).
writer ?= json_writer.
writer->set_option( option = if_sxml_writer=>co_opt_linebreaks ).
writer->set_option( option = if_sxml_writer=>co_opt_indent ).
CALL TRANSFORMATION demo_st_json_table SOURCE carriers = carriers
RESULT XML json_writer.
"Get JSON-String from writer
DATA json TYPE xstring.
json = json_writer->get_output( ).
"Two ways of displaying the JSON string
display_as_text( json ).
display_as_html( json ).
"Back to ABAP, verify that transformation is symmetric
DATA result LIKE carriers.
CALL TRANSFORMATION demo_st_json_table SOURCE XML json
RESULT carriers = result.
ASSERT result = carriers.
ENDMETHOD.
METHOD display_as_text.
"Simple output of JSON in text edit control
DATA text TYPE string.
text = cl_abap_codepage=>convert_from( json ).
cl_demo_text=>show_string( text ).
ENDMETHOD.
METHOD display_as_html.
"Beautified output of JSON in HTML browser
DATA html TYPE string.
CALL TRANSFORMATION sjson2html SOURCE XML json
RESULT XML html.
cl_abap_browser=>show_html( html_string = html ).
ENDMETHOD.
ENDCLASS.
START-OF-SELECTION.
demo=>main( ).
Note
If you replace type = if_sxml=>co_xt_json with type = if_sxml=>co_xt_xml10 when creating the sXML-writer, it becomes an XML-writer and you will get JSON-XML instead of JSON from the writer.
