Re: Parsing JSON data into a data structure without knowing variable's names -- RPG400-L

Sorry it is from my own Open Source project called powerEXT Core, the link
should be under
my name.
It is at the moment frozen because I have som node.js issues in the next
version but the
shown procedure (jsonToField) are included in the download.

On Sat, Aug 12, 2017 at 7:19 PM, Maria Lucia Stoppa <mlstoppa@xxxxxxxxx>
wrote:

Joe, FFD may not be necessary because I can use external D specification
copied through /Copy option instead. I will do some test using pointers and
deep YAJL available functions: maybe combining the two a new option may
arise.

Henrik, I am not sure about what you are meant to say. Looking at your code
it seems to me that you are using a library different from YAJL where your
function comes from. In this case a program generator will help by adding
standardised code to my sources, included specific reference to variable
names.
Il 12/Ago/2017 19:02, "Henrik Rützou" <hr@xxxxxxxxxxxx> ha scritto:

Since most JSON comes in from AJAX the only rule there is, is that there

is

no rules
and most inexperienced programmers do think that they are smarter than
standards
and main stream ways of doing things ;-)

On Sat, Aug 12, 2017 at 6:44 PM, Henrik Rützou <hr@xxxxxxxxxxxx> wrote:

Okay, then take this input http://blablabla.pgm?parm1=
abcd&parm2=defg&json1={....}&json2={...}

Program generator?

On Sat, Aug 12, 2017 at 6:34 PM, Joe Pluta <joepluta@xxxxxxxxxxxxxxxxx

wrote:

Yes, this seems like the most straightforward approach, Jon. Kind of
like a web service generator that builds code based on a WSDL. Sure,
THEORETICALLY you could map the data dynamically by looking at an
externally described data structure, and done properly you'd only have

to

do it once, but the overhead of parsing an FFD every time could be
significant.

I like the generated adapter technique. A good balance between
flexibility and performance. As long as you can avoid the temptation

to

tweak the generated code... :)

I concur with the others that in a language such as RPG this is not

readily done. However, by constraining the problem space it can be

done. I

wrote up this technique some 10 years ago

http://ibmsystemsmag.com/ibmi/

developer/rpg/how-flexible-are-your-calculations-/ <
http://ibmsystemsmag.com/ibmi/developer/rpg/how-flexible-ar
e-your-calculations-/> and this followup article which took it one

step

further.
http://ibmsystemsmag.com/ibmi/developer/rpg/even-more-flexib
le-calculations/ <http://ibmsystemsmag.com/ibmi
/developer/rpg/even-more-flexible-calculations/> providing you know

the

names of all fields involved, then this could work but I don't think

t

is

the best solution.

Instead in your case I would suggest writing a simple code generator
would be a more practical way of handling the multiple parameter sets

that

you have. Rather than try and write a completely generic program

write

a

generic generator that spits out the RPG to do the JSON to DS mapping

for

each of your DS. If the parameter set changes regen the code.

Nested structures would be harder to handle but by no means

impossible.

Jon Paris

www.partner400.com
www.SystemiDeveloper.com

On Aug 12, 2017, at 3:12 AM, Maria Lucia Stoppa <mlstoppa@xxxxxxxxx>

wrote:

Hello,

I am new to this forum, but I have done some research related to

JSON

and
couldn't find anything similar to my issue.

I am working on a proof of concept to code new programs in order to
parse
the only received parameter formed as a JSON object into a data
structure.

I explain it better: previously, all our programs received a single
parameter defined as an external data structure, so as soon as

*entry

plist
operation code is executed the data structure and all the fields in

it

were
filled in and made available for programs to use them (quite common
solution). External data structure are defined as PF without member

and

can
be used by any program that need to call the one which received it

as

a

parameter to perform a specific function.

Now we are moving our ERP's graphic interface to web: it means that

a

program call can be executed by a store procedure called either by

web

applications or by RPG programs. To serve the purpose of having a

quick

UI
response, parameters are passed coded in a JSON object and new

programs

have been coded to parse JSON input parameter field by field using

SK's

JSON APIs (thanks!).

I am guessing whether I can expand and generalize this behavior by
coding a
general routine which takes an external definition of JSON (even

nested)

structure and assigns each object's name found into JSON parameter

to

its
corresponding variable name's value.

My nightmares are: firstly, today's external DS are one level only

and I

can't figure out how to represent nested levels; secondly how to
dynamically associate the value of JSON pair to its corresponding
variable's value according to its type.

One general idea might be to code some external D specifications to

be

used
through /COPY option, which represent JSON structure in terms of
qualified
names and types, array included. Then JSON objects can be read

element

by
element but how can I address the right DS variable without

explicitly

write its name?

Can you suggest me some technique I haven't explored yet or any

other

way
to approach the problem?

Thank you

--
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--
Regards,
Henrik Rützou

http://powerEXT.com <http://powerext.com/>

--
Regards,
Henrik Rützou

http://powerEXT.com <http://powerext.com/>
--
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