postgresql/contrib/spi/insert_username.c
2001-03-22 04:01:46 +00:00

80 lines
2.4 KiB
C

/*
* insert_username.c
* $Modified: Thu Oct 16 08:13:42 1997 by brook $
*
* insert user name in response to a trigger
* usage: insert_username (column_name)
*/
#include "executor/spi.h" /* this is what you need to work with SPI */
#include "commands/trigger.h" /* -"- and triggers */
#include "miscadmin.h" /* for GetUserName() */
extern Datum insert_username(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(insert_username);
Datum
insert_username(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
Trigger *trigger; /* to get trigger name */
int nargs; /* # of arguments */
Datum newval; /* new value of column */
char **args; /* arguments */
char *relname; /* triggered relation name */
Relation rel; /* triggered relation */
HeapTuple rettuple = NULL;
TupleDesc tupdesc; /* tuple description */
int attnum;
/* sanity checks from autoinc.c */
if (!CALLED_AS_TRIGGER(fcinfo))
elog(ERROR, "insert_username: not fired by trigger manager");
if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
elog(ERROR, "insert_username: can't process STATEMENT events");
if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
elog(ERROR, "insert_username: must be fired before event");
if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
rettuple = trigdata->tg_trigtuple;
else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
rettuple = trigdata->tg_newtuple;
else
elog(ERROR, "insert_username: can't process DELETE events");
rel = trigdata->tg_relation;
relname = SPI_getrelname(rel);
trigger = trigdata->tg_trigger;
nargs = trigger->tgnargs;
if (nargs != 1)
elog(ERROR, "insert_username (%s): one argument was expected", relname);
args = trigger->tgargs;
tupdesc = rel->rd_att;
attnum = SPI_fnumber(tupdesc, args[0]);
if (attnum < 0)
elog(ERROR, "insert_username (%s): there is no attribute %s", relname, args[0]);
if (SPI_gettypeid(tupdesc, attnum) != TEXTOID)
elog(ERROR, "insert_username (%s): attribute %s must be of TEXT type",
relname, args[0]);
/* create fields containing name */
newval = DirectFunctionCall1(textin,
CStringGetDatum(GetUserName(GetUserId())));
/* construct new tuple */
rettuple = SPI_modifytuple(rel, rettuple, 1, &attnum, &newval, NULL);
if (rettuple == NULL)
elog(ERROR, "insert_username (%s): %d returned by SPI_modifytuple",
relname, SPI_result);
pfree(relname);
return PointerGetDatum(rettuple);
}