insert_username.c File Reference

#include "postgres.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/rel.h"

Include dependency graph for insert_username.c:

Go to the source code of this file.

Functions
Datum	insert_username (PG_FUNCTION_ARGS)
	PG_FUNCTION_INFO_V1 (insert_username)
Variables
	PG_MODULE_MAGIC

---

Function Documentation

Datum insert_username

(

PG_FUNCTION_ARGS

)

Definition at line 25 of file insert_username.c.

References CALLED_AS_TRIGGER, CStringGetTextDatum, elog, ereport, errcode(), errmsg(), ERROR, GetUserId(), GetUserNameFromId(), NULL, pfree(), PointerGetDatum, SPI_fnumber(), SPI_getrelname(), SPI_gettypeid(), SPI_modifytuple(), SPI_result, TEXTOID, TriggerData::tg_event, TriggerData::tg_newtuple, TriggerData::tg_relation, TriggerData::tg_trigger, TriggerData::tg_trigtuple, Trigger::tgnargs, TRIGGER_FIRED_BEFORE, TRIGGER_FIRED_BY_INSERT, TRIGGER_FIRED_BY_UPDATE, and TRIGGER_FIRED_FOR_ROW.

{
    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_ROW(trigdata->tg_event))
        /* internal error */
        elog(ERROR, "insert_username: must be fired for row");
    if (!TRIGGER_FIRED_BEFORE(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 = CStringGetTextDatum(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);
}

PG_FUNCTION_INFO_V1

(

insert_username

)

---

Variable Documentation

PG_MODULE_MAGIC

Definition at line 18 of file insert_username.c.