On Tue, Aug 04, 2009 at 04:13:19PM +0100, Martin Evans wrote:
> Tim Bunce wrote:
> > On Tue, Aug 04, 2009 at 01:19:43PM +0100, Martin Evans wrote:
> >> This is my second attempt to try and get some insight into how to do
> >> this. The DBD::ODBC::ping method calls DBI::_new_sth to obtain a new
> >> statement handle but DBD::ODBC prevents creating a new statement handle
> >> when not connected (you cannot actually get one even if you wanted). The
> >> problem is once DBD::ODBC discovers we are not connected it does:
> >>
> >> DBIh_SET_ERR_CHAR(
> >> h, imp_xxh, Nullch, 1,
> >> "Cannot allocate statement when disconnected from the database",
> >> "08003", Nullch);
> >>
> >> and because PrintError is on the error is output and because RaiseError
> >> is on the error handler is called. Most people are calling ping when not
> >> connected and do not want this error and I wanted to mask it by
> >> temporarily disabling PrintError and RaiseError but it does not seem to
> >> work for me.
> >>
> >> Initially I tried using local $dbh->{PrintError} = 0 but this did not
> >> work. Then I remembered I needed to call STORE from inside the driver so
> >> changed to $dbh->STORE('PrintError', 0); but that does not work either.
> >
> > That should work. Try calling $dbh->dump_handle after (and after doing
> > the same for RaiseError) that to see what the state of the handle is.
> >
> > Tim.
> >
> > p.s. You could also try using the HandleError attribute, but the above
> > should
> > work so let's find out what's happening there first.
>
> Thanks for the help Tim.
>
> Ignoring RaiseError for now as I'm imagining it will work (once it
> works) the same as PrintError. The ping sub is currently:
>
> sub ping {
> my $dbh = shift;
> my $state = undef;
>
> my ($catalog, $schema, $table, $type);
>
> $catalog = q{};
> $schema = q{};
> $table = 'NOXXTABLE';
> $type = q{};
>
> print "PrintError=", $dbh->FETCH('PrintError'), "\n";
> my $pe = $dbh->FETCH('PrintError');
> $dbh->STORE('PrintError', 0);
> $dbh->dump_handle;
> my $evalret = eval {
> # create a "blank" statement handle
> my $sth = DBI::_new_sth($dbh, { 'Statement' => "SQLTables_PING" })
> or return 1;
>
> DBD::ODBC::st::_tables($dbh,$sth, $catalog, $schema, $table, $type)
> or return 1;
> $sth->finish;
> return 0;
> };
> $dbh->STORE('PrintError', $pe);
> if ($evalret == 0) {
> return 1;
> } else {
> return 0;
> }
> }
>
> and the following perl and output are observed:
>
> perl -Iblib/lib -Iblib/arch -le 'use DBI;$h = DBI->connect();print
> "ping=",$h->ping(),"\n";$h->disconnect; print "ping=",$h->ping(), "\n";'
> PrintError=1
>
> DBI::dump_handle (dbh 0x82c382c, com 0x82c4560, imp DBD::ODBC::db):
> FLAGS 0x100217: COMSET IMPSET Active Warn PrintWarn AutoCommit
> ERR ''
> ERRSTR '[unixODBC][Easysoft][SQL Server Driver][SQL
> Server]Changed language setting to us_english. (SQL-01000)
> [unixODBC][Easysoft][SQL Server Driver][SQL Server]Changed database
> context to 'master'. (SQL-01000)'
> PARENT DBI::dr=HASH(0x82bc5e0)
> KIDS 0 (0 Active)
> Name 'baugi'
> ping=1
>
> PrintError=1
>
> DBI::dump_handle (dbh 0x82c382c, com 0x82c4560, imp DBD::ODBC::db):
> FLAGS 0x100213: COMSET IMPSET Warn PrintWarn AutoCommit
> PARENT DBI::dr=HASH(0x82bc5e0)
> KIDS 0 (0 Active)
> Name 'baugi'
> DBD::ODBC::db ping failed: Cannot allocate statement when disconnected
> from the database at -e line 1.
> ping=0
>
> I don't know if it is anything of a clue but if I fail to restore
> PrintError with STORE at the end of ping, the error is not seen in the
> second call to ping).
Ah! The DBI is reporting the error information that's stored in the
handle when the ping method *returns*.
You need to use $h->set_err(...) to clear the error state before
returning.
Tim.
