Re: Handling null-capable fields with program-described file -- reading externally described using program defined layout

Thanks Chuck. I tried, but same result. I also tried ALWNULL(*YES) even though the help text says it's the same as *INPUTONLY just because it was a value that wasn't mentioned in the manual for the H-spec keyword. No luck though.

Actually, that help text is pretty much the same thing the manual (Chapter 13. Control Specification Keywords) says about the ALWNULL H-spec. The important phrase is "from externally described" input-only database files. There's a link from that section back to Chapter 10. Data Types and Definitions where there's a section on "Database Null Value Support". That's where I got the excerpt I quoted.

You mentioned thinking a null key field might've caused the problem -- I had to look at the program, but it doesn't have a K in the F-spec. And it's input-only:

fINPUT if f32766 disk usropn Input file
f extfile(InpFile) extmbr(InpMbr)

I had tried looking at the same file with DSPPFM which gave me some hope that it should work, but maybe I should be using some other method of reading the files, e.g. that API whose name escapes me at the moment, fread, fget. I'll look into that tomorrow.

*Peter Dow* /
Dow Software Services, Inc.
909 793-9050
pdow@xxxxxxxxxxxxxxx <mailto:pdow@xxxxxxxxxxxxxxx> /


CRPence wrote:

The help text from CRTRPGMOD, instead of the snipped reference to RPGLE doc:

Allow null values (ALWNULL) - Help
_*INPUTONLY_
Specifies that the ILE RPG module can successfully read records
with null-capable fields containing null values from externally
described input-only database files. When a record containing
null values is retrieved, no data mapping errors occur and the
database default values are placed into any fields which contain
null values. The module cannot do any of the following:
- use null-capable key fields
- create or update records containing null-capable fields
- determine whether a null-capable field is actually null
while the module is running
- set a null-capable field to be null.

Maybe try that parameter specification on the create command, instead of [or in addition to] using the H-Spec to see if that resolves.

DSPPFM uses that feature of the database, but DSPPFM never uses any keyed access/lookup nor update. Although not RPG, DSPPFM also reads the non-described data. At first glance of the help text, I thought maybe a key field is null capable, giving rise to the error. But with a program described definition of the file.? Well... it seemed more likely than having declared the input file for update.?
Anyhow if eventually the feature gets activated, just like DSPPFM, using that feature to Allow Null values prevents the application from knowing or designating the datum as the NULL value [except possibly to infer from the value being the default for the field].

Regards, Chuck