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  1.  Home
  2. RPG400-L
  3. February 2022

RE: YAJLDTAGEN with SQL into DS

Daniel,

Thank you for the response.
I do have IFS functions in qsys2… do these need prototyped for use in RPG?
SPECIFIC_NAME
ROUTINE_SCHEMA
ROUTINE_NAME
ROUTINE_TYPE
QSQIFSJOBI
QSYS2
IFS_JOB_INFO
FUNCTION
QSQIFSOBJL
QSYS2
IFS_OBJECT_LOCK_INFO
FUNCTION
QSQIFSOBJP
QSYS2
IFS_OBJECT_PRIVILEGES
FUNCTION
QSQIFSOBJI
QSYS2
IFS_OBJECT_REFERENCES_INFO
FUNCTION
QSQIFSOBJS
QSYS2
IFS_OBJECT_STATISTICS
FUNCTION
QSQIFSREAD
QSYS2
IFS_READ
FUNCTION
QSQIFSREADBINARY
QSYS2
IFS_READ_BINARY
FUNCTION
QSQIFSREADUTF8
QSYS2
IFS_READ_UTF8
FUNCTION
QSQIFSWRITE
QSYS2
IFS_WRITE
PROCEDURE
QSQIFSWRITEBINARY
QSYS2
IFS_WRITE_BINARY
PROCEDURE
QSQIFSWRITEUTF8
QSYS2
IFS_WRITE_UTF8
PROCEDURE

As for the “batches”… typically, I like to “chunk” the data into one or more files to limit number of arrays.

In my example, I was using an SQL cursor to fetch 50 rows at a time – creating a file for each set:

IFSfile_0.json
IFSfile_1.json
Etc.

Most of the time, it creates a single file (json doc) but if someone were to run the process for a month (instead of a day) it may be 5-10 files.
Maybe I’m off base… but I like to limit the file size (many web services do the same using paging).

Thanks,
Greg

From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Daniel Gross
Sent: Friday, February 4, 2022 3:18 PM
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: YAJLDTAGEN with SQL into DS

Hi Greg,

AFAIK the IFS_ functions were part of TR9 on 7.3.

You can try this:

select * from qsys2.sysroutines where routine_name like 'IFS_%';


The cust_group_id was somehow a placeholder for a grouping because you have written, that you have to output the JSON for “various batches” - so “cust_group_id” stands for your various batches - maybe a customer id, or something you construct using a case-expression.

When designing a SQL solution, you should start thinking backwards from what your output should look like. As you didn't wrote how the "batches" are built, I "invented" a "cust_group_id" field, to group the data for the batches.

I only tested it with some synthetic data which I set up on pub400.com (which runs 7.4). To make and say more, I would need much more information.

Kind regards,
Daniel


Am 04.02.2022 um 19:49 schrieb Greg Wilburn <gwilburn@xxxxxxxxxxxxxxxxxxxxxxx<mailto:gwilburn@xxxxxxxxxxxxxxxxxxxxxxx>>:

Daniel,

I was trying to experiment with your code below, but I have two issues.

The compiler says object IFS_WRITE in QSYS2 not found. Pretty sure I have the latest PTF groups loaded on v7r3
Second, I don't quite understand where "cust_group_id" is coming from... I'm assuming it is an incrementing number.

Thx,
Greg

-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx<mailto:rpg400-l-bounces@xxxxxxxxxxxxxxxxxx>> On Behalf Of Daniel Gross
Sent: Thursday, February 3, 2022 1:18 AM
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx<mailto:rpg400-l@xxxxxxxxxxxxxxxxxx>>
Subject: Re: YAJLDTAGEN with SQL into DS

Hi Jon,

no - I didn’t miss these parts - and both are easily solved using SQL.

As Birgitta mentions one can select the JSON string INTO a string (or even a 2GB BLOB field if needed) and write that out using RPG - very easy.

Or you can wrap an QSYS2.IFS_WRITE(….) around the JSON_OBJECT function. That way you could also write multiple batches into multiple IFS files using a GROUP BY clause and JOINING a table with the output file names or deriving the output file names somehow on the result set level.

exec sql select qsys2.ifs_write(:ifs_file_name,
json_object(
'Customers' : json_arrayagg(
json_object(
'addr_line1' : addr_line1,
'addr_line2' : addr_line2,
'city' : city,
'state' : state,
'zip' : zip,
'phone' : phone,
'email' : email
)
)
)
)
from mytable
where ….;

Or even somehow more dynamically like that:

exec sql select qsys2.ifs_write('/path/to/your/file/output_file_‘ || char(cust_group_id) || '.json',
json_object(
'Customers' : json_arrayagg(
json_object(
'addr_line1' : addr_line1,
'addr_line2' : addr_line2,
'city' : city,
'state' : state,
'zip' : zip,
'phone' : phone,
'email' : email
)
)
)
)
from mytable
where ….
group by cust_group_id;

But I think that this is not the point. Why I have mentioned a SQL solution is because SQL on IBM i is definitely the future. And using SQL as a READ/CHAIN replacement is not how SQL should be used.

I once read somewhere “if you have to use a SQL cursor, you haven’t understood the problem” - even if I wouldn’t go so far, it’s clear, that you have to lay off "procedural thinking" when using SQL, because of SQL's “anti-procedural” and “result-descriptive” nature.

Kind regards,
Daniel

P.S.: Of course Birgitta is 100% right about always checking SQLCODE after doing SQL in RPG programs - even a simple "if sqlcode <> *zero; …“ is better than nothing.


Am 03.02.2022 um 05:42 schrieb Birgitta Hauser <Hauser@xxxxxxxxxxxxxxx<mailto:Hauser@xxxxxxxxxxxxxxx>>:

plus I think he has need to use different output file names in the IFS which your code doesn't do.
Writing to the IFS is just an SELECT ... INTO into the IFS File:
Here is the complete code that is necessary to execute the SQL Statement and write the data into the IFS.

DCL-S YourIFSFile SQLTYPE(CLOB_FILE);

YourIFSFile_Name = '/YourDir/YourDir2/YourIFSFile.json'; //IFS File Name
YourIFSFile_NL = %Len(%Trim(YourIFSFile_Name)); //IFS File Name Length
YourIFSFile_FO = SQFOVR; //File Operation - Write the data to the IFS - Replace if exists

Exec SQL select json_object(
'Customers' : json_arrayagg(
json_object(
'addr_line1' : addr_line1,
'addr_line2' : addr_line2,
'city' : city,
'state' : state,
'zip' : zip,
'phone' : phone,
'email' : email
)
)
)
Into :YourIFSFile
from mytable;
//Check SQL Code or SQL State here ... and then continue

... and done!
... there are also SQL Stored for writing directly into the IFS: IFS_WRITE, IFS_WRITE_UTF8, IFS_WRITE_BINARY

... and for those who do not need more than this, I've even written a piece of open source code.
https://github.com/BirgittaHauser/Generate-XML-and-JSON

Mit freundlichen Grüßen / Best regards

Birgitta Hauser


"Shoot for the moon, even if you miss, you'll land among the stars." (Les Brown)
"If you think education is expensive, try ignorance." (Derek Bok)
"What is worse than training your staff and losing them? Not training them and keeping them!"
„Train people well enough so they can leave, treat them well enough so they don't want to.“ (Richard Branson)


-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx<mailto:rpg400-l-bounces@xxxxxxxxxxxxxxxxxx>> On Behalf Of Jon Paris
Sent: Donnerstag, 3. Februar 2022 00:43
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx<mailto:rpg400-l@xxxxxxxxxxxxxxxxxx>>
Subject: Re: YAJLDTAGEN with SQL into DS

I think you missed the bits about starting and stopping at arbitrary points/batches Daniel - plus I think he has need to use different output file names in the IFS which your code doesn't do.


Jon P.

On Feb 2, 2022, at 4:55 PM, Daniel Gross <daniel@xxxxxxxx<mailto:daniel@xxxxxxxx>> wrote:

Hi Greg,

after fiddling around for 10 minutes or so, I came up with this SQL statement:

select json_object(
'Customers' : json_arrayagg(
json_object(
'addr_line1' : addr_line1,
'addr_line2' : addr_line2,
'city' : city,
'state' : state,
'zip' : zip,
'phone' : phone,
'email' : email
)
)
)
from mytable;

Which results in the following JSON string (which I formatted to be better readable):

{
"Customers":[
{
"addr_line1":"64a N Williams St",
"addr_line2":"",
"city":"Crystal Lake",
"state":"IL",
"zip":"60014",
"phone":"7792204179",
"email":"marvinstoys@xxxxxxxxx<mailto:marvinstoys@xxxxxxxxx>"
},
{
"addr_line1":"267 Main St",
"addr_line2":"",
"city":"Huntington",
"state":"NY",
"zip":"11743",
"phone":"6315498743",
"email":"lsdolls@xxxxxxx<mailto:lsdolls@xxxxxxx>"
}]
}

I hope I understood your problem correctly.

Of course I understand, that it is always a "problem" to make big changes to existing code - but IMHO modernization starts exactly there.

HTH
Daniel

Am 02.02.2022 um 22:06 schrieb Greg Wilburn <gwilburn@xxxxxxxxxxxxxxxxxxxxxxx<mailto:gwilburn@xxxxxxxxxxxxxxxxxxxxxxx>>:

Chris,

Thank you for your response. I did not realize that I could SELECT "INTO" a qualified data structure. But it worked perfectly.

I set up my SQL Cursor in a procedure called OpenCursor() then:

OpenCursor();

Dow FetchCursor(AllCustomers.Customers);
WriteJson(Stmf);
jsonCount += 1;
enddo;

CloseCursor();

...in WriteJson()
DATA-GEN AllCustomers
%DATA(inStmf: 'doc=file output=clear countprefix=num_')
%GEN('YAJLDTAGEN');

//-------------------------------------------------------------------
-----------
// Fetch the Next Record
//
//-------------------------------------------------------------------
-----------

dcl-proc FetchCursor;

dcl-pi FetchCursor ind;
rec likeds(AllCustomers.Customers) dim(50);
end-pi;

sqlRows = 0;

Exec Sql
Fetch Next From sqlcsr for :maxrows rows
Into :rec ;

if SqlStt <> sqlOK;
return *off;
endif;

Exec Sql Get Diagnostics :sqlRows = ROW_COUNT;

AllCustomers.num_Customers = sqlRows;

return *on;

end-proc;


-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx<mailto:rpg400-l-bounces@xxxxxxxxxxxxxxxxxx>> On Behalf Of
Hiebert, Chris
Sent: Wednesday, February 2, 2022 1:19 PM
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx<mailto:rpg400-l@xxxxxxxxxxxxxxxxxx>>
Subject: RE: YAJLDTAGEN with SQL into DS

Try:

dcl-ds AllCustomers qualified;
num_Customers uns(5);

dcl-ds Customers qualified dim(50) inz;

addr_line1 varchar(40) inz('');

addr_line2 varchar(40) inz('');

city varchar(40) inz('');

state varchar(3) inz('');

zip varchar(10) inz('');

phone varchar(22) inz('');

email varchar(50) inz('');

end-ds;
End-ds;

AllCustomers.num_Customers = sqlRows;


DATA-GEN AllCustomers

%DATA(inStmf: 'doc=file output=clear countprefix=num_')

%GEN('YAJLDTAGEN');



If that doesn't work with the SQL you can keep the other customers array and continue to load that with sql and then:

%Subarr( AllCustomers.Customers:1:SqlRows ) =
%SUBARR(customers:1:sqlRows);

Then run the DATA-GEN.

Chris Hiebert
Senior Programmer/Analyst
Disclaimer: Any views or opinions presented are solely those of the author and do not necessarily represent those of the company.

From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx<mailto:rpg400-l-bounces@xxxxxxxxxxxxxxxxxx>> On Behalf Of
Greg Wilburn
Sent: Tuesday, February 1, 2022 3:03 PM
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx<mailto:rpg400-l@xxxxxxxxxxxxxxxxxx>>
Subject: YAJLDTAGEN with SQL into DS


So I have a working application where I've used SQL data access to load a Data structure.



dcl-ds Customers qualified dim(50) inz;

addr_line1 varchar(40) inz('');

addr_line2 varchar(40) inz('');

city varchar(40) inz('');

state varchar(3) inz('');

zip varchar(10) inz('');

phone varchar(22) inz('');

email varchar(50) inz('');

end-ds;



I then use YAJLDTAGEN to create the JSON file:

DATA-GEN %SUBARR(customers:1:sqlRows)

%DATA(inStmf: 'doc=file output=clear')

%GEN('YAJLDTAGEN');



Output looks like this:

[

{

"addr_line1": "64a N Williams St",

"addr_line2": "",

"city": "Crystal Lake",

"state": "IL",

"zip": "60014",

"phone": "7792204179",

"email": "marvinstoys@xxxxxxxxx<mailto:marvinstoys@xxxxxxxxx>"

},

{

"addr_line1": "267 Main St",

"addr_line2": "",

"city": "Huntington",

"state": "NY",

"zip": "11743",

"phone": "6315498743",

"email": "lsdolls@xxxxxxx<mailto:lsdolls@xxxxxxx>"

}

]





The endpoint has asked for this:

{

"Customers": [

{

"addr_line1": "64a N Williams St",

"addr_line2": "",

"city": "Crystal Lake",

"state": "IL",

"zip": "60014",

"phone": "7792204179",

"email": "marvinstoys@xxxxxxxxx<mailto:marvinstoys@xxxxxxxxx>"

},

{

"addr_line1": "267 Main St",

"addr_line2": "",

"city": "Huntington",

"state": "NY",

"zip": "11743",

"phone": "6315498743",

"email": "lsdolls@xxxxxxx<mailto:lsdolls@xxxxxxx>"

}

]

}



I know how to create the DS... but then I'm not sure how to do Exec SQL INTO that DS.

I'm pretty sure the "into variable" cannot be "json.Customers".



What am I missing?



TIA,

Greg


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