Example RPG to decode JSON from IFS using YAJL

{{ "users": [{ "userID": "@123", "firstName": "Billy", "lastName": "Bob", "initials": "123", "company": 110, "division": 30, "department": 325, "secProfile": "" }, { "userID": "AAATEMP", "firstName": "Albert", "lastName": "Smith", "initials": "AAA", "company": 110, "division": 1, "department": 1, "secProfile": "" }, { "userID": "AAATEST", "firstName": "Andy", "lastName": "Tester", "initials": "AAA", "company": 110, "division": 1, "department": 530, "secProfile": "AAT" }, { "userID": "AAA3", "firstName": "Fred", "lastName": "Blogs", "initials": "AA3", "company": 110, "division": 1, "department": 1, "secProfile": "AAA" }, { "userID": "AATEST", "firstName": "AA", "lastName": "TEST", "initials": "AAT", "company": 110, "division": 1, "department": 1, "secProfile": "" }, { "userID": "ABB", "firstName": "Abba", "lastName": "Dancing Queen", "initials": "", "company": 110, "division": 1, "department": 1, "secProfile": "" }, { "userID": "BINGBONG", "firstName": "Bing", "lastName": "Bong", "initials": "BB", "company": 110, "division": 2, "department": 2, "secProfile": "" }, { "userID": "LITTENN", "firstName": "Nick", "lastName": "Litten", "initials": "NJL", "company": 1, "division": 1, "department": 123, "secProfile": "Secret Squirrel" }]}

USERID varchar(100);
FIRSTNAME varchar(100);
LASTNAME varchar(100);
INITIALS varchar(100);
COMPANY int(10);
DIVISION int(10);
DEPARTMENT int(10);

**FREE
/TITLE JSON_TABLE Decode JSON using Y.A.J.L. - Proof of Concept

// ------------------------------------------------------
// PROGRAM CREATION OVERRIDES:
//
// Create as a Module and bind into ILE program
//
// JSNIFSYAJL.sqlrpgle (fully /free)
//
// This demonstrates reading JSON data from an IFS file and then
// parsing that JSON to break out the subffields using Y.A.J.L.
// Subfields within the objects are retrieved by their field names.
//
// The JSON data is loaded into a data structure suitable
// for display from a program debugger.
//
// Compile - ADDLIBLE : LITTENN LMDTA06NL YAJL
//
// Check input data -
// DSPLNK OBJ( ** value from IFSFilename ** )
//
// MODIFICATION HISTORY:
//
// 07/17/2017 nick.litten V1.00
//


ctl-opt dftactgrp(*no) actgrp('LITTENN')
option(*nodebugio:*srcstmt:*nounref)
bnddir('YAJL') alwnull(*inputonly)
datfmt(*ISO) decedit('0.')
copyright('| JSNIFSYAJL 1.0 06/27/2017 Use YAJL to read JSON from IFS and Parse.');

/include yajl_h

// IFS file with JSON code that we will be reading and decoding
dcl-c ifsFilename
      const('/home/littenn/getwebjsn.json');

dcl-ds jsonFields qualified template;
  USERID varchar(100);
  FIRSTNAME varchar(100);
  LASTNAME varchar(100);
  INITIALS varchar(100);
  COMPANY int(10);
  DIVISION int(10);
  DEPARTMENT int(10);
end-ds;

dcl-ds result qualified;
  success ind;
  errmsg varchar(500);
  jsonArray likeds(jsonFields) dim(9999);
end-ds;

dcl-s docNode like(yajl_val);
dcl-s list like(yajl_val);
dcl-s node like(yajl_val);
dcl-s val like(yajl_val);

dcl-s Count int(10);
dcl-s lastElement int(10) inz;
dcl-s errMsg varchar(500) inz('');

dcl-s strTimeStamp timestamp inz; // start of pgm
dcl-s strJsonTimeStamp timestamp inz; // start of JSON decode logic
dcl-s endTimeStamp timestamp inz; // used to calculate duration

// Parms for logging-text being sent back into program message queue
dcl-pr QMHSNDPM extpgm('QMHSNDPM');
  *n char(7) const; // MsgID
  *n char(20) const; // MsgFile
  *n char(32767) const options(*varsize); // MsgData
  *n int(10) const; // MsgDtaLen
  *n char(10) const; // MsgType
  *n char(10) const; // StackEntry
  *n int(10) const; // StackCount
  *n char(4); // MsgKey
  *n char(32767) options(*varsize); // ErrorCode
end-pr;

dcl-ds ErrorCode;
  BytesProv int(10) inz(0);
  BytesAvail int(10) inz(0);
end-ds;

dcl-s joblogMsg char(200);
dcl-s MsgKey char(4);

/Title [---------- MAINLINE ---------- ]

strTimeStamp=%timestamp();

// Load JSON in from the IFS file using YAJL
docNode = yajl_stmf_load_tree( ifsFilename : errMsg );

// If it loaded then lets decode it:
if errMsg = '';

 strJsonTimeStamp=%timestamp();

 // Write the JSON *header* level values
 node = YAJL_object_find(docNode: 'success');
 result.success = YAJL_is_true(node);

 node = YAJL_object_find(docNode: 'errmsg');
 result.errmsg = YAJL_get_string(node);

 list = YAJL_object_find(docNode: 'users');

 // Write the JSON *data array* level values
 Count = 0;
 dow YAJL_ARRAY_LOOP( list: Count: node );

  lastElement = Count;

  val = YAJL_object_find(node: 'userID');
  result.jsonArray(Count).userID = yajl_get_string(val);

  val = YAJL_object_find(node: 'firstName');
  result.jsonArray(Count).firstName = yajl_get_string(val);

  val = YAJL_object_find(node: 'lastName');
  result.jsonArray(Count).lastName = yajl_get_string(val);

  val = YAJL_object_find(node: 'initials');
  result.jsonArray(Count).initials = yajl_get_string(val);

  val = YAJL_object_find(node: 'company');
  result.jsonArray(Count).company = yajl_get_number(val);

  val = YAJL_object_find(node: 'division');
  result.jsonArray(Count).division = yajl_get_number(val);

  val = YAJL_object_find(node: 'department');
  result.jsonArray(Count).department = yajl_get_number(val);

 enddo;

 yajl_tree_free(docNode);

 // Set Ending timestamps and calculate runtime
 endTimeStamp=%timestamp();

 joblogMsg = 'JSNIFSYAJL Completed with ' +
       %char(lastElement) +
       ' elements. Total runtime:' +
       %char(%diff(endTimeStamp:strTimeStamp:*mseconds)) +
       ' YAJL DECODE only:' +

       %char(%diff(endTimeStamp:strJsonTimeStamp:*mseconds)) ;

 // stick that message into the joblog so we

 // can clearly see the runtime
 QMHSNDPM( 'CPF9897'
        : 'QCPFMSG *LIBL'
        : joblogMsg
        : %len(%trimr(joblogMsg))
        : '*DIAG'
        : '*'
        : 0
        : MsgKey
        : ErrorCode );

else;
 // If unable to load JSON data from the IFS then

 // tell the world
 result.success = *off;
 result.errmsg = 'Aaargh! I couldnt read the IFS file';
endif;

*inlr = *on;

return;

JSNIFSYAJL Completed with 91 elements. Total runtime:11000 YAJL DECODE only:4000