CODEWITHSUNDEEP
xmlxsdschemarestriction
gysyky
gysyky

Reputation: 470

XML Schema force two attributes to be different

In my XML I have defined categories 

<category id="3" parent-category-id="2">
    <name>Child category</name>
</category>

As you can see I have a category element, which can have a parent category defined. Both attributes are defined in my XML Schema file:

<xs:attribute name="id" use="required" type="xs:string" />
<xs:attribute name="parent-category-id" use="optional" type="xs:string" />

I also have keys and keyrefs set in my XSD file. Now I wonder if this is possible to somehow restrict parent-category-id, so that it cannot point to self id. For example I can write:

<category id="3" parent-category-id="3">

and such XML file will still validate, althought it shouldn't.

My keys and keyrefs are:

<xs:key name="ID">
    <xs:selector xpath="categories/category" />
    <xs:field xpath="@id" />
</xs:key>

<xs:keyref name="PARENT_CATEGORY_ID_REF" refer="ID">
    <xs:selector xpath="categories/category" />
    <xs:field xpath="@parent-category-id" />
</xs:keyref>

It would be great, if I could add some kind of restriction, that would tell the validator that id cannot == parent-category-id. Any ideas?

Upvotes: 1

Views: 180

Answers (1)

Nate Allen
Nate Allen

Reputation: 3239

If you have an XSD validator that supports version 1.1, you can use an assert after the xs:attribute elements to enforce your restriction:

<xs:assert test="@id != @parent-category-id"/>

Personally I'm having trouble locating a validator that does support 1.1 though. Version 1.0 does not support assert.

Upvotes: 1

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