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

On Aug 12, 2017, at 10:38 AM, Henrik Rützou <hr@xxxxxxxxxxxx> wrote:

Hi Maria,

You should take at look at YAJL that is a C service program that
reads/writes JSON.

Scott Klement has made a RPG-wrapper around it
http://www.scottklement.com/yajl/

More on reading JSON in RPG:

https://www.nicklitten.com/rpg-example-reading-json-using-yajl-ifs/




On Sat, Aug 12, 2017 at 4:07 PM, Maria Lucia Stoppa <mlstoppa@xxxxxxxxx>
wrote:

Henrik,
I know your points are true and that's how we have done so far, but I am
trying to figure out a general routine to be copied in many different
programs so variable's name can't be hard coded.
Furthermore, JSON structure doesn't necessary reflects data structure
fields order, only names and types in order to be valued when a variable
with the same name and of the same type is present.


2017-08-12 15:45 GMT+02:00 Henrik Rützou <hr@xxxxxxxxxxxx>:

It is generally a very bad idea to map JSON to a datastructure (or
anything) without using
the variable name's since the whole idea in JSON is that you may include

or

exclude
variables and beside that present them in a random sequence.

On Sat, Aug 12, 2017 at 9:12 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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Maria Lucia Stoppa
mlstoppa@xxxxxxxxx
--
This is the RPG programming on the IBM i (AS/400 and iSeries) (RPG400-L)
mailing list
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Regards,
Henrik Rützou

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