Michael's solution won't work if xdmp:random() happens to return two
small numbers. For example, the following produces nothing:
let $x := concat(
xdmp:integer-to-hex(random(100)),
xdmp:integer-to-hex(random(100))
)
return substring($x, 21, 12)
It can be fixed by testing for a minimum string length for $x then
calling the function again if the test fails:
return
if (string-length($x < 32))
then generate-uuid-v4()
else string-join((substring($x, 1, 8),...), "-")
Otherwise, you could try something like this
(: Functions :)
define function random-hex(
$length as xs:integer
) as xs:string {
string-join(
for $n in 1 to $length
return xdmp:integer-to-hex(xdmp:random(15)),
""
)
}
define function generate-uuid-v4() as xs:string {
string-join(
(
random-hex(8),
random-hex(4),
random-hex(4),
random-hex(4),
random-hex(12)
),
"-"
)
}
(: Query :)
generate-uuid-v4()
Best
Tim Finney
UVa Press
On Fri, 2007-08-10 at 16:01 -0700, Michael Blakeley wrote:
> I happen to have one in front of me right now. Note that there are at
> least five flavors of UUID - I chose to implement type-4.
>
> (: this is a v4 UUID :)
> define function generate-uuid-v4()
> as xs:string
> {
> let $x := concat(
> xdmp:integer-to-hex(xdmp:random()),
> xdmp:integer-to-hex(xdmp:random())
> )
> return string-join((
> substring($x, 1, 8), substring($x, 9, 4),
> substring($x, 13, 4), substring($x, 17, 4), substring($x, 21, 14)
> ), '-'
> )
> }
>
> Ref: http://en.wikipedia.org/wiki/UUID
>
> -- Mike
>
> Gary Vidal wrote:
> >
> >
> > I was wondering if anybody has implemented a uuid (universally unique
> > identifier) function in Xquery. I would like to use this to generate
> > id's or a comparable id generation scheme
> >
> >
> >
> > Regards,
> >
> >
> >
> > Gary Vidal
> >
> > Sr. .Net Developer
> >
> > Tel: 212-592-4946
> >
> > [EMAIL PROTECTED]
> >
> >
> >
> >
> >
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > General mailing list
> > [email protected]
> > http://xqzone.com/mailman/listinfo/general
>
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