[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XSD: Behaviour of <xsd:unique>
Cams Ismael <Ismael.Cams@s...> writes: > What should be the behaviour when the optional tag <d> is missing. Both > MSXML 4.0 and xsdvalid still check on the f1 attribute. So if we leave out > the <d> tags in the example the file is invalid, because there are two > <mayHaveDaughter> elements with a f1 attribute value 'c'. However with xsv > no error is generated, and with XercesJ-2.3.0 I get following error: 'Not > enough values specified for <unique> identity constraint specified for > element'. > > So my question is, if one of the optional elements is not available, should > this element be ignored or not. The recs seems to be not clear about that. I believe the REC [1] is clear on this: "For each node in the *target node set* all of the {fields}, with that node as the context node, [must] evaluate to either an empty node-set or a node-set with exactly one member, which must have a simple type." This condition is satisfied for your modified instance -- some of the fields yield a one-member node-set whose single member has a simple type, some yield an empty node-set. "Call the subset of the *target node set* for which all the {fields} evaluate to a node-set with exactly one member which is an element or attribute node with a simple type the *qualified node set*." OK, so in some cases you now find your target node drops out, because one of its fields yields an empty-node set. Since it's not in the *qualified node set*, no error is possible, since the constraint is xsd:unique, not xsd:key. ht [1] http://www.w3.org/TR/xmlschema-1/#section-Identity-constraint-Definition-Validation-Rules -- 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@c... URL: http://www.ltg.ed.ac.uk/~ht/ [mail really from me _always_ has this .sig -- mail without it is forged spam]
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