Re: Misunderstanding with JDBCR4

[Jevgeni Astanovski <jevgeniast@xxxxxxxxx>]

In fact I have already solved the problem.
A little googling around for "operational descriptor"....

I just had to modify my header file and add one row for JDBC_GetCol:

#pragma descriptor(void JDBC_GETCOL(void , void, ""))

With this RPG understood, that number of parameters is 3 and returned
me the correct value of nullInd.


Of course also added the same pragma to all other functions that deal
wit nullInd - just in case...

Thanks,

Jevgeni.


On Fri, Dec 16, 2016 at 4:04 PM, Ron Unknown <qgenesist@xxxxxxxxxxx> wrote:
> Jevgeni,
>
> I am not sure, it has been so long since I have messed with 400s,  but is the pointer given an initial value before calling the program? something like:
>
> Dcl Y-Ptr *     init(*null) or based(*null)
>
> not sure of the syntax any more, before it is called so that the sytem knows it is a pointer?
>
>
> ________________________________
> From: C400-L <c400-l-bounces@xxxxxxxxxxxx> on behalf of Jevgeni Astanovski <jevgeniast@xxxxxxxxx>
> Sent: Friday, December 16, 2016 2:55 AM
> To: Bare Metal Programming IBM i (AS/400 and iSeries)
> Subject: [C400-L] Misunderstanding with JDBCR4
>
> Hi, collegues
> Having a challenge of accessing external database from my ILE/C
> program, looked at Scott Klement JDBCR4.
> As I do not write RPG, had to spend some time porting library header
> from RPG to C. Not a big job.
> Generally works fine.
> However when I tried to see how JDBC_GetCol returns NullInd in case
> field is empty, ran into a problem.
>
> JDBC_GetCol is prototyped so:
>
> VAR32767 JDBC_GETCOL(RESHANDLE *, int, char *) ;
> VAR32767 and RESHANDLE are my defined types and they work fine.
>
> I call this function in my program:
>
> RESHANDLE rs ;
> char NullInd ;
> VAR32767 Field ;
>
> Field = JDBC_GETCOL(&rs, 48, &NullInd) ;
>
> It returns field value fine, however NullInd is always unchanged -
> field is empty or not.
> Run in debugger mode to see what Scott's program does.
> His function looks so:
>
> P JDBC_GetCol B export
> D JDBC_GetCol PI 32767A varying
> D rs like(ResultSet)
> D col 10I 0 value
> D nullInd 1N options(*nopass:*omit)
> D result s 32767A varying
> D str s like(jstring)
> D null s 1N inz(*OFF)
>
> /free
>
> jdbc_begin_object_group(5);
>
> monitor;
> str = getColString(rs: col);
> if (str = *NULL);
>   result = '';
>   null = *ON;
> else;
>   result = r(str);
> endif;
> on-error;
> null = *ON;
> result = '';
> endmon;
> jdbc_end_object_group();
> if (%parms >= 3 and %addr(nullInd)<>*NULL);
>   nullInd = Null;
> endif;
>
> return result;
>
> /end-free
>
> Sorry for the formatting...
>
> What my debugging show is that Null variable has a proper value, but
> is never assigned to nullInd.
> I added NumParms variable and assigned value of %parms to it.
> From that I saw that NumParms is -1, however all 3 parameters are passed.
>
> Had a look at the manual for %parms.
> It says the following:
> "The value returned by %PARMS will be -1 if the system can determine
> that the operational
> descriptor was not passed, but in some cases when the system cannot detect this,
> the value returned by %PARMS may be an incorrect value that is zero or greater."
>
> Is there anything I can do about it?
>
> Any advise will be highly appreciated...
>
> Jevgeni.
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