Line data    Source code

       1              : /*
       2              :  * contrib/spi/insert_username.c
       3              :  *
       4              :  * insert user name in response to a trigger
       5              :  * usage:  insert_username (column_name)
       6              :  */
       7              : #include "postgres.h"
       8              : 
       9              : #include "access/htup_details.h"
      10              : #include "catalog/pg_type.h"
      11              : #include "commands/trigger.h"
      12              : #include "executor/spi.h"
      13              : #include "miscadmin.h"
      14              : #include "utils/builtins.h"
      15              : #include "utils/rel.h"
      16              : 
      17            0 : PG_MODULE_MAGIC_EXT(
      18              :                                         .name = "insert_username",
      19              :                                         .version = PG_VERSION
      20              : );
      21              : 
      22            0 : PG_FUNCTION_INFO_V1(insert_username);
      23              : 
      24              : Datum
      25            0 : insert_username(PG_FUNCTION_ARGS)
      26              : {
      27            0 :         TriggerData *trigdata = (TriggerData *) fcinfo->context;
      28            0 :         Trigger    *trigger;            /* to get trigger name */
      29            0 :         int                     nargs;                  /* # of arguments */
      30            0 :         Datum           newval;                 /* new value of column */
      31            0 :         bool            newnull;                /* null flag */
      32            0 :         char      **args;                       /* arguments */
      33            0 :         char       *relname;            /* triggered relation name */
      34            0 :         Relation        rel;                    /* triggered relation */
      35            0 :         HeapTuple       rettuple = NULL;
      36            0 :         TupleDesc       tupdesc;                /* tuple description */
      37            0 :         int                     attnum;
      38              : 
      39              :         /* sanity checks from autoinc.c */
      40            0 :         if (!CALLED_AS_TRIGGER(fcinfo))
      41              :                 /* internal error */
      42            0 :                 elog(ERROR, "insert_username: not fired by trigger manager");
      43            0 :         if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
      44              :                 /* internal error */
      45            0 :                 elog(ERROR, "insert_username: must be fired for row");
      46            0 :         if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
      47              :                 /* internal error */
      48            0 :                 elog(ERROR, "insert_username: must be fired before event");
      49              : 
      50            0 :         if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
      51            0 :                 rettuple = trigdata->tg_trigtuple;
      52            0 :         else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
      53            0 :                 rettuple = trigdata->tg_newtuple;
      54              :         else
      55              :                 /* internal error */
      56            0 :                 elog(ERROR, "insert_username: cannot process DELETE events");
      57              : 
      58            0 :         rel = trigdata->tg_relation;
      59            0 :         relname = SPI_getrelname(rel);
      60              : 
      61            0 :         trigger = trigdata->tg_trigger;
      62              : 
      63            0 :         nargs = trigger->tgnargs;
      64            0 :         if (nargs != 1)
      65              :                 /* internal error */
      66            0 :                 elog(ERROR, "insert_username (%s): one argument was expected", relname);
      67              : 
      68            0 :         args = trigger->tgargs;
      69            0 :         tupdesc = rel->rd_att;
      70              : 
      71            0 :         attnum = SPI_fnumber(tupdesc, args[0]);
      72              : 
      73            0 :         if (attnum <= 0)
      74            0 :                 ereport(ERROR,
      75              :                                 (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
      76              :                                  errmsg("\"%s\" has no attribute \"%s\"", relname, args[0])));
      77              : 
      78            0 :         if (SPI_gettypeid(tupdesc, attnum) != TEXTOID)
      79            0 :                 ereport(ERROR,
      80              :                                 (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
      81              :                                  errmsg("attribute \"%s\" of \"%s\" must be type TEXT",
      82              :                                                 args[0], relname)));
      83              : 
      84              :         /* create fields containing name */
      85            0 :         newval = CStringGetTextDatum(GetUserNameFromId(GetUserId(), false));
      86            0 :         newnull = false;
      87              : 
      88              :         /* construct new tuple */
      89            0 :         rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
      90              :                                                                                  1, &attnum, &newval, &newnull);
      91              : 
      92            0 :         pfree(relname);
      93              : 
      94            0 :         return PointerGetDatum(rettuple);
      95            0 : }