conditional processing for XSD elements?

[Piper707]

Hi,

I need to know if there is any way of achieving conditional processing
for XSD elements.

---------------------------------------------------------------
<criteria></criteria> = a complex element
<join_condition></join_condition> = a simple element
---------------------------------------------------------------
EX:

<criteria>....</criteria>
<join_condition>.....</join_condition>
<criteria> .....</criteria>
---------------------------------------------------------------

I need the 1st criteria block to be mandatory. But it makes sense to
have a second criteria block, only if a join condition block has been
provided.

so it would be illegal to have only:
---------------------------------------------------------------
<criteria>....</criteria>
<join_condition>.....</join_condition>
---------------------------------------------------------------
I'm trying to impose the restriction: "if join_condition occurs once, a
criteria block must occur once under it."

I was trying to use the "group" conditional, but it points out
xs:sequence to be illegal, i'm not sure why? -

<xs:group name="criteria_and_join" minOccurs="0">
<xs:sequence>
<xs:element name="join_condition">
<xs:simpleType>
<xs:restriction base="xs:string">
<xs:enumeration value="AND"/>
<xs:enumeration value="OR"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
<xs:element ref="criteria"/> //defined elewhere as a
complex type
</xs:sequence>
</xs:group>

How can achieve the conditional restriction that a criteria block can
only appear provided a join_condition block precedes it (except for the
very first criteria block)?

Thanks
Rohit.

 

[Stan Kitsis [MSFT]]

<xs:sequence>
<xs:element name="criteria"/>
<xs:sequence minOccurs="0">
<xs:element name="join_condition"/>
<xs:element name="criteria"/>
</xs:sequence>
</xs:sequence>

--
Stan Kitsis
Program Manager, XML Technologies
Microsoft Corporation

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[Henry S. Thompson]

The only bug in your example (which should do what you want) (assuming
there is a definition of 'criteria' somewhere), is the presence of the
'minOccurs' attribute, which is not allowed on xs:group (because it's
meaningless -- the min/max on the _reference_ to the group is what
matters).

ht
--
Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
Half-time member of W3C Team
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