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Re: Better diagnostic support in DBI

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From:
pali
Date:
April 7, 2019 16:37
Subject:
Re: Better diagnostic support in DBI
Message ID:
20190407163655.nb3r6rdjz4fpd56z@pali
Hello, I would like to hear some feedback on this DBI API proposal.

Tim, what is opinion for adding that new diagnostic API into DBI?

On Tuesday 29 January 2019 13:16:23 pali@cpan.org wrote:
> CCing DBD::Pg, DBD::Oracle and DBD::ODBC developers. What do you think
> about following diagnostic API in DBI?
> 
> I looked at DBD::Pg and currently it does not support retrieving
> warnings via $dbh->errstr or $dbh->state methods... So I think it that
> my diagnostic API proposal can be useful for DBD::Pg too.
> 
> On Wednesday 23 January 2019 11:15:35 pali@cpan.org wrote:
> > Hi! DBI currently supports 3 functions to retrieve diagnostic
> > informations
> > 
> > https://metacpan.org/pod/DBI#err
> > https://metacpan.org/pod/DBI#errstr
> > https://metacpan.org/pod/DBI#state
> > 
> > which return the last one database native code, message and SQLSTATE.
> > Plus there warning or note information is indicated by zero native code
> > or by empty string in native code.
> > 
> > This API has two big limitations:
> > 
> > 1) It does not support providing database native code for warnings and
> >    note informations.
> > 
> > 2) It does not support providing more warnings, errors or note
> >    informations.
> > 
> > It most cases database native code is what application can "parse" and
> > decide how to handle it. So absence of database native code for warnings
> > or note informations can be a problem -- as currently DBI application
> > needs to parse string message from $dbh->errstr.
> > 
> > Also databases can return more warnings or note informations for the
> > last executed call. For this case DBI defines API for errstr just as:
> > 
> > "The returned string may contain multiple messages separated by newline
> > characters."
> > 
> > So it is harder for DBI application to parse multi warnings. And there
> > is not information for which warning is value from $dbh->state.
> > 
> > 
> > 
> > Based on above two limitations I would like to propose a new API for
> > diagnostic messages (errors, warnings and note / success with
> > information).
> > 
> > New method call "get_diagnostics()" for all DBI handles. It would
> > return array of diagnostics member. Each diagnostic member would contain
> > reference to array with 4 members: type, native code, message, sqlstate.
> > 
> > Type can be non-zero for errors, zero for warnings and empty string for
> > notes / success with information. Like what $dbh->err now returns.
> > 
> > Native code is native database code, same what $dbh->err returns for
> > errors. But for warnings and notes it would also contain database native
> > code, not just false value
> > 
> > Message and sqlstate would return $dbh->errstr and $dbh->state.
> > 
> > Example of usage:
> > 
> >   my @array = $dbh->get_diagnostics();
> >   foreach (@array) {
> >     my ($type, $code, $message, $sqlstate) = @{$_};
> >     if ($type) {
> >       print "Error $code ($sqlstate): $message\n";
> >     } elsif ($type eq '0') {
> >       print "Warning $code ($sqlstate): $message\n";
> >     } else {
> >       # Process success with information message
> >     }
> >   }
> > 
> > What do you think about it?

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