xsd: validating from a selection of groups

[Neil Walker]

Hello,
What I'm trying to achieve is allow within one element either one set of elements or another. I thought I achieved this creating a choice element of either an element or a group and it parsef fine with my old version 4 of xml spy, but it turns out it is incorrect due to 'the group ref to "all" is not the root particle'

As an example, for the element 'data' I want to allow either one set of fields or another, as in:

<data>
 <none />
</data>

Or,

<data>
 <field1 />
 <field2 />
</data>

The xsd I created that achieved this as follows, but it is invalid:

<xs:element name="data" type="formtype" />
 
<xs:group name="form">
 <xs:all>
  <xs:element name="field1" />
  <xs:element name="field2" />
 </xs:all>
</xs:group>
 
<xs:complexType name="formtype">
 <xs:choice>        
  <xs:element name="none" />
  <xs:group ref="form"/>
 </xs:choice>
</xs:complexType> 

The thing I really don't understand is if I change xs:all to xs:sequence then it is valid, yet the difference between the two that I know is simply sequence must all be there and in the right order, and all must all be there but in any order, and I need the elements to be any order.

Any help in fixing this would be appreciated :)

Neil.

[jkmyoung]

The reason is that whenever you use an xs:all it has to be the outermost content of an element. Otherwise, it increases the complexity too much for parsers to handle.
You could change it to a sequence, putting all possible combinations, but if you have many elements in the sequence, it might be too much to list all combinations. eg with the 2 current ones:

<xs:element name="data" type="formtype"/>
<xs:group name="form1">
    <xs:sequence>
        <xs:element name="field1"/>
        <xs:element name="field2"/>
    </xs:sequence>
</xs:group>
<xs:group name="form2">
    <xs:sequence>
        <xs:element name="field2"/>
        <xs:element name="field1"/>
    </xs:sequence>
</xs:group>
<xs:complexType name="formtype">
    <xs:choice>
        <xs:element name="none"/>
        <xs:group ref="form1"/>
        <xs:group ref="form2"/>
    </xs:choice>
</xs:complexType>
 

The usage of <none/> as a marker element is non-standard.

[Neil Walker]

ok thanks, not being allowed to a choice of groups of elements seems like a big omission (unordered). However I can't rearrange them as the code I posted was just a sample, my real xsd has a large amount of fields.

Given what you've said I'm simply going to change my schema to have two different types, e.g.

<data1>
<field1 />
<field2/>
</data1>

and,
<data2>
<none />
</data2>

As for the marker element, that was just me making it simpler, it isn't like that in the real xsd.