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-rw-r--r--contrib/spi/insert_username.c92
1 files changed, 92 insertions, 0 deletions
diff --git a/contrib/spi/insert_username.c b/contrib/spi/insert_username.c
new file mode 100644
index 0000000..a2e1747
--- /dev/null
+++ b/contrib/spi/insert_username.c
@@ -0,0 +1,92 @@
+/*
+ * 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);
+}