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