include$(SRCDIR)/Makefile.global

CONTRIBDIR=$(LIBDIR)/contrib

CFLAGS+=$(CFLAGS_SL) -I$(SRCDIR)/include

CFLAGS+= -DREFINT_VERBOSE

TARGETS= refint$(DLSUFFIX) refint.sql timetravel$(DLSUFFIX) timetravel.sql\

autoinc$(DLSUFFIX) autoinc.sql

autoinc$(DLSUFFIX) autoinc.sql\

insert_username$(DLSUFFIX) insert_username.sql

CLEANFILES+=$(TARGETS)

all::$(TARGETS)

install:: all$(CONTRIBDIR)

$(INSTALL) -c README$(CONTRIBDIR)/README.spi

forfin*.example*.sql*$(DLSUFFIX);do$(INSTALL) -c$$f$(CONTRIBDIR)/$$f;done

$(CONTRIBDIR):

mkdir -p$(CONTRIBDIR)

%.sql:%.source

rm -f$@;\

C=`pwd`;\

sed -e"s:_OBJWD_:$$C:g"\

sed -e"s:_OBJWD_:$(CONTRIBDIR):g"\

-e"s:_DLSUFFIX_:$(DLSUFFIX):g"<$<>$@

clean:

autoinc.source).

4. insert_username.c - function for inserting user names.

You have to create BEFORE INSERT OR UPDATE trigger using the function

insert_username(). You have to specify as a function argument: the column

name (of text type) in which user names will be inserted. Note that user

names will be inserted irregardless of the initial value of the field, so

that users cannot bypass this functionality by simply defining the field to

be NOT NULL.

There is an example in insert_username.example.

To CREATE FUNCTION use insert_username.sql (will be made by gmake from

insert_username.source).

HeapTupleinsert_username (void);

insert_username ()

{

Trigger*trigger;/* to get trigger name */

intnargs;/* # of arguments */

Datumnewval;/* new value of column */

char**args;/* arguments */

char*relname;/* triggered relation name */

Relationrel;/* triggered relation */

HeapTuplerettuple=NULL;

TupleDesctupdesc;/* tuple description */

intattnum;

if (!CurrentTriggerData)

elog(WARN,"insert_username: triggers are not initialized");

if (TRIGGER_FIRED_FOR_STATEMENT(CurrentTriggerData->tg_event))

elog(WARN,"insert_username: can't process STATEMENT events");

if (TRIGGER_FIRED_AFTER(CurrentTriggerData->tg_event))

elog(WARN,"insert_username: must be fired before event");

if (TRIGGER_FIRED_BY_INSERT(CurrentTriggerData->tg_event))

rettuple=CurrentTriggerData->tg_trigtuple;

elseif (TRIGGER_FIRED_BY_UPDATE(CurrentTriggerData->tg_event))

rettuple=CurrentTriggerData->tg_newtuple;

elog(WARN,"insert_username: can't process DELETE events");

rel=CurrentTriggerData->tg_relation;

relname=SPI_getrelname(rel);

trigger=CurrentTriggerData->tg_trigger;

nargs=trigger->tgnargs;

if (nargs!=1)

elog(WARN,"insert_username (%s): one argument was expected",relname);

args=trigger->tgargs;

tupdesc=rel->rd_att;

CurrentTriggerData=NULL;

attnum=SPI_fnumber (tupdesc,args[0]);

if (attnum<0 )

elog(WARN,"insert_username (%s): there is no attribute %s",relname,args[0]);

if (SPI_gettypeid (tupdesc,attnum)!=TEXTOID)

elog(WARN,"insert_username (%s): attribute %s must be of TEXT type",

relname,args[0]);

newval=PointerGetDatum (textin (GetPgUserName ()));

rettuple=SPI_modifytuple (rel,rettuple,1,&attnum,&newval,NULL);

if (rettuple==NULL )

elog (WARN,"insert_username (%s): %d returned by SPI_modifytuple",

relname,SPI_result);

pfree (relname);

return (rettuple);

}

DROP TABLE username_test;

CREATE TABLE username_test (

nametext,

usernametext not null

);

CREATE TRIGGER insert_usernames

BEFORE INSERT OR UPDATE ON username_test

FOR EACH ROW

EXECUTE PROCEDURE insert_username (username);

INSERT INTO username_test VALUES ('nothing');

INSERT INTO username_test VALUES ('null', null);

INSERT INTO username_test VALUES ('empty string', '');

INSERT INTO username_test VALUES ('space', ' ');

INSERT INTO username_test VALUES ('tab', '');

INSERT INTO username_test VALUES ('name', 'name');

SELECT * FROM username_test;

DROP FUNCTION insert_username();

CREATE FUNCTION insert_username()

RETURNS opaque

AS '_OBJWD_/insert_username_DLSUFFIX_'

LANGUAGE 'c';