PQregisterResult(3) libpqtypes Manual PQregisterResult(3)NAMEPQregisterResult - Registers sub-classes, composites and user-defined
types found within a PGresult.
SYNOPSIS
#include <libpqtypes.h>
int PQregisterResult(PGconn *conn, int which, PGregisterType *types,
int count, PGresult *res);
DESCRIPTION
The PQregisterResult() function registers the types found within a
given PGresult, thus this function makes no calls to a PostgreSQL
server since the result data is already available.
The which argument can be PQT_COMPOSITE or PQT_USERDEFINED, but not
PQT_SUBCLASS. The only reason being sub-classes don't talk to the
server so they have no result set.
The types argument is an array containing count types to register.
This array must be identical to what was provided to the originating
PQregisterTypes call.
The res argument is a PGresult normally created by calling PQregister‐
Types followed by PQgetResult. However, it is possible to create your
own result via PQmakeEmptyPGresult, PQsetResultAttrs, PQsetvalue and
call this function. This approach is a bit risky being how the result
set generated by type lookup queries are internal and subject to
change.
EXAMPLES
Using PQregisterResult
The example registers two composite types asynchronously. It is worth
noting that the PGresult obtained via PQgetResult can be cached by an
application and used when creating new connections, as a way to avoid
repeatedly performing type lookups with the server.
PGregisterType comp_types[] = {
{"myschema.simple", NULL, NULL},
{"complex", NULL, NULL}
};
/* asynchronous registration */
if (PQregisterTypes(conn, PQT_COMPOSITE, comp_types, 2, 1))
{
/* example of a typical event loop */
for(;;)
{
int n;
fd_set set;
int fd = PQsocket(conn);
struct timeval tv = {0, 500000};
FD_ZERO(&set);
FD_SET(fd, &set);
n = select(fd + 1, &set, NULL, NULL, &tv); //or kqueue,epoll,poll,etc..
if (n == -1)
{
//error
}
else if (n == 0)
{
//timeout, do other work ....
}
else
{
PGresult *res;
PQconsumeInput(conn);
if(!PQisBusy(conn))
{
/* done */
if(!(res = PQgetResult(conn)))
break;
n = PQregisterResult(conn, PQT_COMPOSITE, comp_types, 2, res);
/* This could also be cached and reused with PQregisterResult */
PQclear(res);
if (!n)
//error, consult PQgeterror()
}
}
}
}
RETURN VALUE
On success, a non-zero value is returned. On error, zero is returned
and PQgeterror(3) will contain an error message.
EXAMPLES
None.
AUTHOR
A contribution of eSilo, LLC. for the PostgreSQL Database Management
System. Written by Andrew Chernow.
REPORTING BUGS
Report bugs to <libpqtypes@esilo.com>.
COPYRIGHT
Copyright (c) 2011 eSilo, LLC. All rights reserved.
This is free software; see the source for copying conditions. There is
NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.
SEE ALSOPQregisterTypes(3), pqt-handlers(3), PQputf(3), PQgetf(3)libpqtypes 2011 PQregisterResult(3)
