postgresql/contrib/spi/insert_username.c
Bruce Momjian 8b4ff8b6a1 Wording cleanup for error messages. Also change can't -> cannot.
Standard English uses "may", "can", and "might" in different ways:

        may - permission, "You may borrow my rake."

        can - ability, "I can lift that log."

        might - possibility, "It might rain today."

Unfortunately, in conversational English, their use is often mixed, as
in, "You may use this variable to do X", when in fact, "can" is a better
choice.  Similarly, "It may crash" is better stated, "It might crash".
2007-02-01 19:10:30 +00:00

94 lines
2.7 KiB
C

/*
* insert_username.c
* $Modified: Thu Oct 16 08:13:42 1997 by brook $
* $PostgreSQL: pgsql/contrib/spi/insert_username.c,v 1.15 2007/02/01 19:10:23 momjian Exp $
*
* 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() */
PG_MODULE_MAGIC;
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))
/* internal error */
elog(ERROR, "insert_username: not fired by trigger manager");
if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
/* internal error */
elog(ERROR, "insert_username: cannot process STATEMENT events");
if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
/* internal error */
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
/* internal error */
elog(ERROR, "insert_username: cannot process DELETE events");
rel = trigdata->tg_relation;
relname = SPI_getrelname(rel);
trigger = trigdata->tg_trigger;
nargs = trigger->tgnargs;
if (nargs != 1)
/* internal error */
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)
ereport(ERROR,
(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
errmsg("\"%s\" has no attribute \"%s\"", relname, args[0])));
if (SPI_gettypeid(tupdesc, attnum) != TEXTOID)
ereport(ERROR,
(errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
errmsg("attribute \"%s\" of \"%s\" must be type TEXT",
args[0], relname)));
/* create fields containing name */
newval = DirectFunctionCall1(textin,
CStringGetDatum(GetUserNameFromId(GetUserId())));
/* construct new tuple */
rettuple = SPI_modifytuple(rel, rettuple, 1, &attnum, &newval, NULL);
if (rettuple == NULL)
/* internal error */
elog(ERROR, "insert_username (\"%s\"): %d returned by SPI_modifytuple",
relname, SPI_result);
pfree(relname);
return PointerGetDatum(rettuple);
}