This reads the JSON from the IFS – decodes it using JSON_TABLE and reports on time taken to perform decode.
In this case the JSON data is a simple layout that looks like this:
{"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":001,"division":1,"department":123,"secProfile":"Secret Squirrel"}]}
This JSON example contains the values:
USERID varchar(100);
FIRSTNAME varchar(100);
LASTNAME varchar(100);
INITIALS varchar(100);
COMPANY int(10);
DIVISION int(10);
DEPARTMENT int(10);
FIRSTNAME varchar(100);
LASTNAME varchar(100);
INITIALS varchar(100);
COMPANY int(10);
DIVISION int(10);
DEPARTMENT int(10);
Now lets read it and break it out into fields, which I am just storing in an array. You could write them to a file just as easily…
**FREE
/TITLE JSON_TABLE Decode JSON using SQL - Proof of Concept
// PROGRAM CREATION OVERRIDES:
// Create as a Module and bind into ILE program
//
// JSNIFSSQL.sqlrpgle (fully /free)
//
// This demonstrates reading JSON data from an IFS file and then
// parsing that JSON using SQL JSON_TABLE functions.
//
// The JSON data is loaded into a data structure suitable
// for display from a program debugger.
//
// MODIFICATION HISTORY:
// 07/17/2017 nick litten V1.0 Created
// 06/20/2021 nick litten V1.1 Removed unused variables for clarity
ctl-opt dftactgrp(*no) actgrp('NICKLITTEN')
option(*nodebugio:*srcstmt:*nounref)
datfmt(*ISO) decedit('0.')
copyright('| JSNIFSSQL V1.1 Use JSONTABLE to read IFS and parse JSON into array.');
// IFS file with JSON code that we will be reading and decoding
dcl-c ifsFilename const('/littenn/getwebjsn.json');
dcl-ds jsonFields qualified;
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;
// procedures and variables for IBM i *APIS to loads IFS into variable
dcl-pr open int(10) extproc('open');
*n pointer value options(*string); // filename
*n int(10) value; // openflags
*n uns(10) value options(*nopass); // mode
*n uns(10) value options(*nopass); // codepage
end-pr;
dcl-pr read int(10) extproc('read');
*n int(10) value; // filehandle
*n pointer value; // datareceived
*n uns(10) value; // nbytes
end-pr;
dcl-pr close int(10) extproc('close');
*n int(10) value; // filehandle
end-pr;
dcl-s Count int(10);
dcl-s Handle int(10);
dcl-s json sqltype(clob:16000000);
dcl-s ifsData char(16000000);
dcl-s ifsDataLen int(10);
dcl-s rc int(10);
dcl-s O_RDONLY int(10) inz(1);
dcl-s O_TEXTDATA int(10) inz(16777216);
dcl-s lastElem int(10);
dcl-ds ErrorCode;
BytesProv int(10) inz(0);
BytesAvail int(10) inz(0);
end-ds;
/Title [---------- MAINLINE ---------- ]
// Open the stream file
Handle = open(%trim(ifsFilename):O_RDONLY + O_TEXTDATA);
// Loop to read the stream file into variable "ifsData"
dou ifsDataLen<1;
Count += 1;
ifsDataLen = read(Handle:%addr(ifsData):%size(ifsData));
enddo;
// Close the stream file
rc = close(Handle);
if ifsData <> *blanks;
// we have the IFS data loaded into variable(ifsData) so lets load
// that variable into the SQL(clob) and process it using the JSON_TABLE
// to break the JSON out into fields for processing. NOTE: we are not
// doing anything with those fields in this program because this is just
// a proof of concept
exec sql
set option naming = *sys,
commit = *none,
usrprf = *user,
dynusrprf = *user,
datfmt = *iso,
closqlcsr = *endmod;
exec sql
declare c1 cursor for
select *
from json_table (:json, '$' // read the JSON data from a string
columns (nested '$.users[*]' columns (userid varchar(100) path
'$.userID', firstname varchar(100) path '$.firstName', lastname
varchar(100) path '$.lastName', initials varchar(100) path
'$.initials', company int path '$.company', division int path
'$.division', department int path '$.department'))) as x;
exec sql
open c1;
exec sql
fetch next from c1
into :jsonfields;
dow sqlstt='00000' or %subst(sqlstt:1:2)='01';
lastelem += 1;
// Store Datastructure values in next element of 'return array'
result.jsonArray(lastelem) = jsonFields;
// here we could do something with each row of data ie: write to file
// or some other business logic.
exec sql
fetch next from c1
into :jsonfields;
enddo;
exec sql
close c1;
result.success = *on;
else;
// If unable to load JSON data from the IFS then tell the world
result.success = *off;
result.errmsg = 'Ouch! I couldnt read the IFS file';
endif;
*inlr = *on;
/TITLE JSON_TABLE Decode JSON using SQL - Proof of Concept
// PROGRAM CREATION OVERRIDES:
// Create as a Module and bind into ILE program
//
// JSNIFSSQL.sqlrpgle (fully /free)
//
// This demonstrates reading JSON data from an IFS file and then
// parsing that JSON using SQL JSON_TABLE functions.
//
// The JSON data is loaded into a data structure suitable
// for display from a program debugger.
//
// MODIFICATION HISTORY:
// 07/17/2017 nick litten V1.0 Created
// 06/20/2021 nick litten V1.1 Removed unused variables for clarity
ctl-opt dftactgrp(*no) actgrp('NICKLITTEN')
option(*nodebugio:*srcstmt:*nounref)
datfmt(*ISO) decedit('0.')
copyright('| JSNIFSSQL V1.1 Use JSONTABLE to read IFS and parse JSON into array.');
// IFS file with JSON code that we will be reading and decoding
dcl-c ifsFilename const('/littenn/getwebjsn.json');
dcl-ds jsonFields qualified;
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;
// procedures and variables for IBM i *APIS to loads IFS into variable
dcl-pr open int(10) extproc('open');
*n pointer value options(*string); // filename
*n int(10) value; // openflags
*n uns(10) value options(*nopass); // mode
*n uns(10) value options(*nopass); // codepage
end-pr;
dcl-pr read int(10) extproc('read');
*n int(10) value; // filehandle
*n pointer value; // datareceived
*n uns(10) value; // nbytes
end-pr;
dcl-pr close int(10) extproc('close');
*n int(10) value; // filehandle
end-pr;
dcl-s Count int(10);
dcl-s Handle int(10);
dcl-s json sqltype(clob:16000000);
dcl-s ifsData char(16000000);
dcl-s ifsDataLen int(10);
dcl-s rc int(10);
dcl-s O_RDONLY int(10) inz(1);
dcl-s O_TEXTDATA int(10) inz(16777216);
dcl-s lastElem int(10);
dcl-ds ErrorCode;
BytesProv int(10) inz(0);
BytesAvail int(10) inz(0);
end-ds;
/Title [---------- MAINLINE ---------- ]
// Open the stream file
Handle = open(%trim(ifsFilename):O_RDONLY + O_TEXTDATA);
// Loop to read the stream file into variable "ifsData"
dou ifsDataLen<1;
Count += 1;
ifsDataLen = read(Handle:%addr(ifsData):%size(ifsData));
enddo;
// Close the stream file
rc = close(Handle);
if ifsData <> *blanks;
// we have the IFS data loaded into variable(ifsData) so lets load
// that variable into the SQL(clob) and process it using the JSON_TABLE
// to break the JSON out into fields for processing. NOTE: we are not
// doing anything with those fields in this program because this is just
// a proof of concept
exec sql
set option naming = *sys,
commit = *none,
usrprf = *user,
dynusrprf = *user,
datfmt = *iso,
closqlcsr = *endmod;
exec sql
declare c1 cursor for
select *
from json_table (:json, '$' // read the JSON data from a string
columns (nested '$.users[*]' columns (userid varchar(100) path
'$.userID', firstname varchar(100) path '$.firstName', lastname
varchar(100) path '$.lastName', initials varchar(100) path
'$.initials', company int path '$.company', division int path
'$.division', department int path '$.department'))) as x;
exec sql
open c1;
exec sql
fetch next from c1
into :jsonfields;
dow sqlstt='00000' or %subst(sqlstt:1:2)='01';
lastelem += 1;
// Store Datastructure values in next element of 'return array'
result.jsonArray(lastelem) = jsonFields;
// here we could do something with each row of data ie: write to file
// or some other business logic.
exec sql
fetch next from c1
into :jsonfields;
enddo;
exec sql
close c1;
result.success = *on;
else;
// If unable to load JSON data from the IFS then tell the world
result.success = *off;
result.errmsg = 'Ouch! I couldnt read the IFS file';
endif;
*inlr = *on;
So what does this do?