XSD密钥/keyref初学者问题 [英] XSD key/keyref beginner question
问题描述
我正在尝试实现一个非常简单的XML模式约束.
I'm trying to implement a very simple XML schema constraint.
元素的 idref 属性 类型< batz> 只能是 允许具有匹配的值 至少一个 id 属性 元素< bar> .
The idref attribute on elements of type <batz> should only be allowed to have a value that matches the id attribute on at least one element <bar>.
如果这对您没有任何意义,那么请只看下面的示例XML文档,我认为它实际上比我用文字尝试更好地解释了它.
If that doesn't make any sense to you then please just look at the example XML-document below, I think it actually explains it better than my attempt to put it in words.
所以,问题是:为什么xmllint允许下面的schema/xml组合通过(它表示文档有效)? 如何解决它以实现所需的约束?
So, question: Why does xmllint let the below schema/xml combination pass (it says the document is valid)? How to fix it to achieve the desired constraint?
架构:
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="test" xmlns="test" elementFormDefault="qualified">
<xs:element name="foo">
<xs:complexType>
<xs:sequence>
<xs:element name="bar" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="id" use="required" type="xs:string" />
</xs:complexType>
</xs:element>
<xs:element name="batz" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="idref" use="required" type="xs:string" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:key name="ID">
<xs:selector xpath="./bar" />
<xs:field xpath="@id" />
</xs:key>
<xs:keyref name="IDREF" refer="ID">
<xs:selector xpath="./batz" />
<xs:field xpath="@idref" />
</xs:keyref>
</xs:element>
</xs:schema>
文档:
<?xml version="1.0"?>
<foo xmlns="test">
<bar id="1" />
<bar id="2" />
<batz idref="1" /> <!-- this should succeed because <bar id="1"> exists -->
<batz idref="3" /> <!-- this should FAIL -->
</foo>
推荐答案
Your XML document, as shown, doesn't include a schemaLocation. When an XML document doesn't reference a schema or DTD, it may pass validation simply by being well-formed XML. (This once happened to a co-worker, using a different validator. I think it's a bug that the validator didn't at least give a warning that it was missing a schema or DTD. But I digress.)
无论如何,可能应该是这样的:
Anyway, it should probably be something like:
<?xml version="1.0"?>
<foo
xmlns="test" <!-- This is bad form, by the way... -->
xsi:schemaLocation="test /path/to/schema/document"
<bar id="1" />
<bar id="2" />
<batz idref="1" /> <!-- this should succeed because <bar id="1"> exists -->
<batz idref="3" /> <!-- this should FAIL -->
</foo>
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