Branch data 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/fmgrprotos.h"
23 : : #include "utils/rel.h"
24 : :
25 : 0 : PG_MODULE_MAGIC_EXT(
26 : : .name = "moddatetime",
27 : : .version = PG_VERSION
28 : : );
29 : :
30 : 0 : PG_FUNCTION_INFO_V1(moddatetime);
31 : :
32 : : Datum
33 : 0 : moddatetime(PG_FUNCTION_ARGS)
34 : : {
35 : 0 : TriggerData *trigdata = (TriggerData *) fcinfo->context;
36 : : Trigger *trigger; /* to get trigger name */
37 : : int nargs; /* # of arguments */
38 : : int attnum; /* positional number of field to change */
39 : : Oid atttypid; /* type OID of field to change */
40 : : Datum newdt; /* The current datetime. */
41 : : bool newdtnull; /* null flag for it */
42 : : char **args; /* arguments */
43 : : char *relname; /* triggered relation name */
44 : : Relation rel; /* triggered relation */
45 : 0 : HeapTuple rettuple = NULL;
46 : : TupleDesc tupdesc; /* tuple description */
47 : :
48 [ # # # # ]: 0 : if (!CALLED_AS_TRIGGER(fcinfo))
49 : : /* internal error */
50 [ # # ]: 0 : elog(ERROR, "moddatetime: not fired by trigger manager");
51 : :
52 [ # # ]: 0 : if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
53 : : /* internal error */
54 [ # # ]: 0 : elog(ERROR, "moddatetime: must be fired for row");
55 : :
56 [ # # ]: 0 : if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
57 : : /* internal error */
58 [ # # ]: 0 : elog(ERROR, "moddatetime: must be fired before event");
59 : :
60 [ # # ]: 0 : if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
61 : : /* internal error */
62 [ # # ]: 0 : elog(ERROR, "moddatetime: cannot process INSERT events");
63 [ # # ]: 0 : else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
64 : 0 : rettuple = trigdata->tg_newtuple;
65 : : else
66 : : /* internal error */
67 [ # # ]: 0 : elog(ERROR, "moddatetime: cannot process DELETE events");
68 : :
69 : 0 : rel = trigdata->tg_relation;
70 : 0 : relname = SPI_getrelname(rel);
71 : :
72 : 0 : trigger = trigdata->tg_trigger;
73 : :
74 : 0 : nargs = trigger->tgnargs;
75 : :
76 [ # # ]: 0 : if (nargs != 1)
77 : : /* internal error */
78 [ # # ]: 0 : elog(ERROR, "moddatetime (%s): A single argument was expected", relname);
79 : :
80 : 0 : args = trigger->tgargs;
81 : : /* must be the field layout? */
82 : 0 : tupdesc = rel->rd_att;
83 : :
84 : : /*
85 : : * This gets the position in the tuple of the field we want. args[0] being
86 : : * the name of the field to update, as passed in from the trigger.
87 : : */
88 : 0 : attnum = SPI_fnumber(tupdesc, args[0]);
89 : :
90 : : /*
91 : : * This is where we check to see if the field we are supposed to update
92 : : * even exists.
93 : : */
94 [ # # ]: 0 : if (attnum <= 0)
95 [ # # ]: 0 : ereport(ERROR,
96 : : (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
97 : : errmsg("\"%s\" has no attribute \"%s\"",
98 : : relname, args[0])));
99 : :
100 : : /*
101 : : * Check the target field has an allowed type, and get the current
102 : : * datetime as a value of that type.
103 : : */
104 : 0 : atttypid = SPI_gettypeid(tupdesc, attnum);
105 [ # # ]: 0 : if (atttypid == TIMESTAMPOID)
106 : 0 : newdt = DirectFunctionCall3(timestamp_in,
107 : : CStringGetDatum("now"),
108 : : ObjectIdGetDatum(InvalidOid),
109 : : Int32GetDatum(-1));
110 [ # # ]: 0 : else if (atttypid == TIMESTAMPTZOID)
111 : 0 : newdt = DirectFunctionCall3(timestamptz_in,
112 : : CStringGetDatum("now"),
113 : : ObjectIdGetDatum(InvalidOid),
114 : : Int32GetDatum(-1));
115 : : else
116 : : {
117 [ # # ]: 0 : ereport(ERROR,
118 : : (errcode(ERRCODE_TRIGGERED_ACTION_EXCEPTION),
119 : : errmsg("attribute \"%s\" of \"%s\" must be type TIMESTAMP or TIMESTAMPTZ",
120 : : args[0], relname)));
121 : : newdt = (Datum) 0; /* keep compiler quiet */
122 : : }
123 : 0 : newdtnull = false;
124 : :
125 : : /* Replace the attnum'th column with newdt */
126 : 0 : rettuple = heap_modify_tuple_by_cols(rettuple, tupdesc,
127 : : 1, &attnum, &newdt, &newdtnull);
128 : :
129 : : /* Clean up */
130 : 0 : pfree(relname);
131 : :
132 : 0 : return PointerGetDatum(rettuple);
133 : : }
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