Age Owner Branch data TLA Line data Source code
1 : : /*
2 : : moddatetime.c
3 : :
4 : : contrib/spi/moddatetime.c
5 : :
6 : : What is this?
7 : : It is a function to be called from a trigger for the purpose of updating
8 : : a modification datetime stamp in a record when that record is UPDATEd.
9 : :
10 : : Credits
11 : : This is 95%+ based on autoinc.c, which I used as a starting point as I do
12 : : not really know what I am doing. I also had help from
13 : : Jan Wieck <jwieck@debis.com> who told me about the timestamp_in("now") function.
14 : : OH, me, I'm Terry Mackintosh <terry@terrym.com>
15 : : */
16 : : #include "postgres.h"
17 : :
18 : : #include "access/htup_details.h"
19 : : #include "catalog/pg_type.h"
20 : : #include "commands/trigger.h"
21 : : #include "executor/spi.h"
22 : : #include "utils/builtins.h"
23 : : #include "utils/rel.h"
24 : :
6529 tgl@sss.pgh.pa.us 25 :UBC 0 : PG_MODULE_MAGIC;
26 : :
8546 27 : 0 : PG_FUNCTION_INFO_V1(moddatetime);
28 : :
29 : : Datum
8721 30 : 0 : moddatetime(PG_FUNCTION_ARGS)
31 : : {
32 : 0 : TriggerData *trigdata = (TriggerData *) fcinfo->context;
33 : : Trigger *trigger; /* to get trigger name */
34 : : int nargs; /* # of arguments */
35 : : int attnum; /* positional number of field to change */
36 : : Oid atttypid; /* type OID of field to change */
37 : : Datum newdt; /* The current datetime. */
38 : : bool newdtnull; /* null flag for it */
39 : : char **args; /* arguments */
40 : : char *relname; /* triggered relation name */
41 : : Relation rel; /* triggered relation */
9255 bruce@momjian.us 42 : 0 : HeapTuple rettuple = NULL;
43 : : TupleDesc tupdesc; /* tuple description */
44 : :
8721 tgl@sss.pgh.pa.us 45 [ # # # # ]: 0 : if (!CALLED_AS_TRIGGER(fcinfo))
46 : : /* internal error */
7570 47 [ # # ]: 0 : elog(ERROR, "moddatetime: not fired by trigger manager");
48 : :
4937 49 [ # # ]: 0 : if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
50 : : /* internal error */
51 [ # # ]: 0 : elog(ERROR, "moddatetime: must be fired for row");
52 : :
53 [ # # ]: 0 : if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
54 : : /* internal error */
7570 55 [ # # ]: 0 : elog(ERROR, "moddatetime: must be fired before event");
56 : :
8721 57 [ # # ]: 0 : if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
58 : : /* internal error */
4937 59 [ # # ]: 0 : elog(ERROR, "moddatetime: cannot process INSERT events");
8721 60 [ # # ]: 0 : else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
61 : 0 : rettuple = trigdata->tg_newtuple;
62 : : else
63 : : /* internal error */
6282 bruce@momjian.us 64 [ # # ]: 0 : elog(ERROR, "moddatetime: cannot process DELETE events");
65 : :
8721 tgl@sss.pgh.pa.us 66 : 0 : rel = trigdata->tg_relation;
9255 bruce@momjian.us 67 : 0 : relname = SPI_getrelname(rel);
68 : :
8721 tgl@sss.pgh.pa.us 69 : 0 : trigger = trigdata->tg_trigger;
70 : :
9255 bruce@momjian.us 71 : 0 : nargs = trigger->tgnargs;
72 : :
73 [ # # ]: 0 : if (nargs != 1)
74 : : /* internal error */
7570 tgl@sss.pgh.pa.us 75 [ # # ]: 0 : elog(ERROR, "moddatetime (%s): A single argument was expected", relname);
76 : :
9255 bruce@momjian.us 77 : 0 : args = trigger->tgargs;
78 : : /* must be the field layout? */
79 : 0 : tupdesc = rel->rd_att;
80 : :
81 : : /*
82 : : * This gets the position in the tuple of the field we want. args[0] being
83 : : * the name of the field to update, as passed in from the trigger.
84 : : */
85 : 0 : attnum = SPI_fnumber(tupdesc, args[0]);
86 : :
87 : : /*
88 : : * This is where we check to see if the field we are supposed to update
89 : : * even exists.
90 : : */
2714 tgl@sss.pgh.pa.us 91 [ # # ]: 0 : if (attnum <= 0)
7570 92 [ # # ]: 0 : ereport(ERROR,
93 : : (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
94 : : errmsg("\"%s\" has no attribute \"%s\"",
95 : : relname, args[0])));
96 : :
97 : : /*
98 : : * Check the target field has an allowed type, and get the current
99 : : * datetime as a value of that type.
100 : : */
4910 101 : 0 : atttypid = SPI_gettypeid(tupdesc, attnum);
102 [ # # ]: 0 : if (atttypid == TIMESTAMPOID)
103 : 0 : newdt = DirectFunctionCall3(timestamp_in,
104 : : CStringGetDatum("now"),
105 : : ObjectIdGetDatum(InvalidOid),
106 : : Int32GetDatum(-1));
107 [ # # ]: 0 : else if (atttypid == TIMESTAMPTZOID)
108 : 0 : newdt = DirectFunctionCall3(timestamptz_in,
109 : : CStringGetDatum("now"),
110 : : ObjectIdGetDatum(InvalidOid),
111 : : Int32GetDatum(-1));
112 : : else
113 : : {
7570 114 [ # # ]: 0 : ereport(ERROR,
115 : : (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
116 : : errmsg("attribute \"%s\" of \"%s\" must be type TIMESTAMP or TIMESTAMPTZ",
117 : : args[0], relname)));
118 : : newdt = (Datum) 0; /* keep compiler quiet */
119 : : }
2714 120 : 0 : newdtnull = false;
121 : :
122 : : /* Replace the attnum'th column with newdt */
123 : 0 : rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
124 : : 1, &attnum, &newdt, &newdtnull);
125 : :
126 : : /* Clean up */
9255 bruce@momjian.us 127 : 0 : pfree(relname);
128 : :
8721 tgl@sss.pgh.pa.us 129 : 0 : return PointerGetDatum(rettuple);
130 : : }
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