Hi,
Finally, I can give the demo of using large objects interface in php.
the test table:
create table lo_test (id serial,raster oid,primary key(id)
);
file: lo_insert.php
<html>
<?php
$db = pg_connect("dbname=template1 user=postgres");
if (!$db) die;
pg_exec($db, "begin");
$oid=pg_locreate($db);
echo "oid=$oid<br>\n";
$handle = pg_loopen ($db, $oid, "w");
echo ("handle=$handle<br>\n");
$fp = fopen ("/etc/rc.d/rc.local", "r");
echo "$fp";
while (!feof($fp)) {pg_lowrite($handle, fread($fp, 4096));
}
fclose($fp);
pg_loclose($handle);
pg_exec($db, "insert into lo_test (raster) values ($oid)");
pg_exec($db, "commit");
pg_close($db);
?>
</html>
file: lo_read.php
<html>
<?php
$db = pg_connect("dbname=template1 user=postgres");
if (!$db) die;
pg_exec($db, "begin");
pg_exec($db, 'select raster from lo_test order by raster desc');
$record = @pg_fetch_array($db, 1);
$oid=$record[0];
echo "$oid<br>\n";
$handle = pg_loopen ($db, $oid, "r");
echo ("$handle\n");
//pg_loreadall($handle);
while ($buf=pg_loread($handle, 80)) {echo nl2br($buf);
}
pg_loclose($handle);
pg_exec($db, "commit");
pg_close($db);
?>
</html>
file: lo_delete.php
<html>
<?php
$db = pg_connect("dbname=template1 user=postgres");
if (!$db) die;
pg_exec($db, "begin");
pg_exec($db, 'select id, raster from lo_test order by raster desc');
$record = @pg_fetch_array($db, 1);
$oid=$record[1];
echo "$oid<br>\n";
pg_lounlink ($oid);
pg_exec($db, sprintf('delete from lo_test where id = %s', $record[0]));
pg_exec($db, "commit");
pg_close($db);
?>
</html>
There is a better way to delete the large object associated with the record.
create trigger like this:
CREATE FUNCTION lo_test_del () RETURNS OPAQUE AS '
BEGINperform lo_unlink(OLD.raster);RETURN OLD;
END;
' LANGUAGE 'plpgsql';
CREATE TRIGGER "tg_lo_test_del" BEFORE DELETE ON "lo_test" FOR EACH ROW EXECUTE PROCEDURE "lo_test_del" ();
when you run
'delete from lo_test where id = 1'
the large object will be deleted in cascade.
regards
Danny Chen
dannychen@fishinteractive.com
