Hello everybody.

I would like to set an uniqueness constraint by checking more than one
attribute.
So:
....
<foo a1="a" a2="a"/>
<foo a1="a" a2="b"/>
<foo a1="a" a2="c"/>

Should be ok.
But:
....
<foo a1="a" a2="a"/>
<foo a1="a" a2="b"/>
<foo a1="a" a2="a"/>

Shouldn't.

How should I write my constraint?

I tried
<xs:unique name="U1">
<xs:selector xpath="tn:foo"/>
<xs:field xpath="@a1"/>
<xs:field xpath="@a2"/>
</xs:unique>

but it doesn't work. Any hint?

Thank you

Lemon Tree writes:
[color=blue]
> I would like to set an uniqueness constraint by checking more than one
> attribute.
> So:
> ...
> <foo a1="a" a2="a"/>
> <foo a1="a" a2="b"/>[/color]
[color=blue]
> Should be ok, but:
> ...
> <foo a1="a" a2="a"/>
> <foo a1="a" a2="b"/>
> <foo a1="a" a2="a"/>
>
> Shouldn't.
>
> I tried
> <xs:unique name="U1">
> <xs:selector xpath="tn:foo"/>
> <xs:field xpath="@a1"/>
> <xs:field xpath="@a2"/>
> </xs:unique>[/color]

That looks correct to me as far as it goes -- did you add the above
xs:unique to an element which will end up with tn:foo children?

You need to show us more of the schema, more of the instance, and tell
us what validator you're using.

ht
--
Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
Half-time member of W3C Team
2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
URL: http://www.ltg.ed.ac.uk/~ht/
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