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
17PG_MODULE_MAGIC;
18
19PG_FUNCTION_INFO_V1(insert_username);
20
21Datum
22insert_username(PG_FUNCTION_ARGS)
23{
24 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 HeapTuple rettuple = NULL;
33 TupleDesc tupdesc; /* tuple description */
34 int attnum;
35
36 /* sanity checks from autoinc.c */
37 if (!CALLED_AS_TRIGGER(fcinfo))
38 /* internal error */
39 elog(ERROR, "insert_username: not fired by trigger manager");
40 if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
41 /* internal error */
42 elog(ERROR, "insert_username: must be fired for row");
43 if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
44 /* internal error */
45 elog(ERROR, "insert_username: must be fired before event");
46
47 if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
48 rettuple = trigdata->tg_trigtuple;
49 else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
50 rettuple = trigdata->tg_newtuple;
51 else
52 /* internal error */
53 elog(ERROR, "insert_username: cannot process DELETE events");
54
55 rel = trigdata->tg_relation;
56 relname = SPI_getrelname(rel);
57
58 trigger = trigdata->tg_trigger;
59
60 nargs = trigger->tgnargs;
61 if (nargs != 1)
62 /* internal error */
63 elog(ERROR, "insert_username (%s): one argument was expected", relname);
64
65 args = trigger->tgargs;
66 tupdesc = rel->rd_att;
67
68 attnum = SPI_fnumber(tupdesc, args[0]);
69
70 if (attnum <= 0)
71 ereport(ERROR,
72 (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
73 errmsg("\"%s\" has no attribute \"%s\"", relname, args[0])));
74
75 if (SPI_gettypeid(tupdesc, attnum) != TEXTOID)
76 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 newval = CStringGetTextDatum(GetUserNameFromId(GetUserId(), false));
83 newnull = false;
84
85 /* construct new tuple */
86 rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
87 1, &attnum, &newval, &newnull);
88
89 pfree(relname);
90
91 return PointerGetDatum(rettuple);
92}
93