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insert_username.c
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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 
18 
20 
21 Datum
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 */
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 }
int SPI_fnumber(TupleDesc tupdesc, const char *fname)
Definition: spi.c:760
Oid SPI_gettypeid(TupleDesc tupdesc, int fnumber)
Definition: spi.c:891
Oid GetUserId(void)
Definition: miscinit.c:282
#define TEXTOID
Definition: pg_type.h:324
#define PointerGetDatum(X)
Definition: postgres.h:564
int errcode(int sqlerrcode)
Definition: elog.c:575
PG_MODULE_MAGIC
HeapTuple tg_trigtuple
Definition: trigger.h:35
void pfree(void *pointer)
Definition: mcxt.c:992
#define ERROR
Definition: elog.h:43
Datum insert_username(PG_FUNCTION_ARGS)
#define ereport(elevel, rest)
Definition: elog.h:122
uintptr_t Datum
Definition: postgres.h:374
Trigger * tg_trigger
Definition: trigger.h:37
HeapTuple tg_newtuple
Definition: trigger.h:36
char * SPI_getrelname(Relation rel)
Definition: spi.c:909
#define NULL
Definition: c.h:226
#define CALLED_AS_TRIGGER(fcinfo)
Definition: trigger.h:25
char * GetUserNameFromId(Oid roleid, bool noerr)
Definition: miscinit.c:690
TriggerEvent tg_event
Definition: trigger.h:33
#define newval
PG_FUNCTION_INFO_V1(insert_username)
HeapTuple heap_modify_tuple_by_cols(HeapTuple tuple, TupleDesc tupleDesc, int nCols, int *replCols, Datum *replValues, bool *replIsnull)
Definition: heaptuple.c:864
#define TRIGGER_FIRED_BEFORE(event)
Definition: trigger.h:88
#define TRIGGER_FIRED_BY_INSERT(event)
Definition: trigger.h:70
int errmsg(const char *fmt,...)
Definition: elog.c:797
int16 tgnargs
Definition: reltrigger.h:37
#define CStringGetTextDatum(s)
Definition: builtins.h:90
#define PG_FUNCTION_ARGS
Definition: fmgr.h:150
#define elog
Definition: elog.h:219
#define TRIGGER_FIRED_FOR_ROW(event)
Definition: trigger.h:82
#define TRIGGER_FIRED_BY_UPDATE(event)
Definition: trigger.h:76
Relation tg_relation
Definition: trigger.h:34