1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
|
/*
* contrib/spi/insert_username.c
*
* insert user name in response to a trigger
* usage: insert_username (column_name)
*/
#include "postgres.h"
#include "access/htup_details.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"
PG_MODULE_MAGIC;
PG_FUNCTION_INFO_V1(insert_username);
Datum
insert_username(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
Trigger *trigger; /* to get trigger name */
int nargs; /* # of arguments */
Datum newval; /* new value of column */
bool newnull; /* null flag */
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(), false));
newnull = false;
/* construct new tuple */
rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
1, &attnum, &newval, &newnull);
pfree(relname);
return PointerGetDatum(rettuple);
}
|
