lwgeom_triggers.c

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/**********************************************************************
 *
 * PostGIS - Spatial Types for PostgreSQL
 * http://postgis.net
 *
 * PostGIS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * PostGIS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with PostGIS.  If not, see <http://www.gnu.org/licenses/>.
 *
 **********************************************************************
 *
 * Copyright (C) 2004 Refractions Research Inc.
 *
 **********************************************************************/


#include "postgres.h"
#include "executor/spi.h"       /* this is what you need to work with SPI */
#include "commands/trigger.h"   /* ... and triggers */

#include "../postgis_config.h"
#include "lwgeom_pg.h"
#include "utils/rel.h"

Datum cache_bbox(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(cache_bbox);
Datum cache_bbox(PG_FUNCTION_ARGS)
{
        TriggerData *trigdata = (TriggerData *) fcinfo->context;
        Trigger *trigger;
        TupleDesc   tupdesc;
        HeapTuple   rettuple;
        bool        isnull;
        Datum in, out;
        int attno, ret;

        /* make sure it's called as a trigger at all */
        if (!CALLED_AS_TRIGGER(fcinfo))
                elog(ERROR, "cache_bbox: not called by trigger manager");

        /*
         * make sure it's called with at least one argument
         * (the geometry fields)
         */
        if ( trigdata->tg_trigger->tgnargs != 1 )
                elog(ERROR, "trigger 'cache_bbox' must be called with one argument");

        trigger = trigdata->tg_trigger;

        /* tuple to return to executor */
        if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
                rettuple = trigdata->tg_newtuple;
        else
                rettuple = trigdata->tg_trigtuple;

        /* Do nothing when fired by delete, after or for statement */
        if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
        {
                elog(NOTICE, "Useless cache_box trigger fired by DELETE");
                return PointerGetDatum(rettuple);
        }
        if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
        {
                elog(NOTICE, "Useless cache_box trigger fired AFTER");
                return PointerGetDatum(rettuple);
        }
        if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
        {
                elog(NOTICE, "Useless cache_box trigger fired for STATEMENT");
                return PointerGetDatum(rettuple);
        }

        tupdesc = trigdata->tg_relation->rd_att;

        /* Connect to SPI manager */
        if ((ret = SPI_connect()) < 0)
                elog(ERROR, "cache_bbox: SPI_connect returned %d", ret);

        /* Find number of requested argument */
        attno = SPI_fnumber(tupdesc, trigger->tgargs[0]);
        if ( attno == SPI_ERROR_NOATTRIBUTE )
                elog(ERROR, "trigger %s can't find attribute %s",
                     trigger->tgname, trigger->tgargs[0]);

        /* Find number of requested argument */
        if ( strcmp(SPI_gettype(tupdesc, attno), "geometry") )
                elog(ERROR, "trigger %s requested to apply to a non-geometry field (%s)", trigger->tgname, trigger->tgargs[0]);

        /* Get input lwgeom */
        in = SPI_getbinval(rettuple, tupdesc, attno, &isnull);

        if ( ! isnull )
        {
                out = PointerGetDatum(DirectFunctionCall1(LWGEOM_addBBOX, in));

                rettuple = SPI_modifytuple(trigdata->tg_relation, rettuple,
                                           1, &attno, &out, NULL);
        }

        /* Disconnect from SPI */
        SPI_finish();

        return PointerGetDatum(rettuple);
}