对 xsd 实施进一步的限制:任何? [英] Enforce further constraints on xsd:any?

问题描述

我有一个 XSD 1.0 序列，它定义了一组元素，其中一些元素可能是可选的，但不能出现多次，并且还以 <xsd:any minOccurs="0 结尾" maxOccurs="unbounded" namespace="##any" processContents="lax"/> 标记，以便用户在以编程方式导出符合标准的 XML 时以最简单的方式添加自己的数据元素(即理想情况下无需他们定义自己的命名空间/XSD).

I have an XSD 1.0 sequence that defines a set of elements, some of which may be optional but none of which can occur more than once, and which also ends with an <xsd:any minOccurs="0" maxOccurs="unbounded" namespace="##any" processContents="lax"/> tag in order to enable users to add their own data elements in the easiest possible way when programmatically exporting conforming XML (i.e. ideally without requiring them to define their own namespace/XSD).

在处理用户生成的 XML 时，我将忽略他们通过 标签添加的任何自定义元素，但我想知道是否有办法强制元素的唯一性名称，以便我可以确定它们不会放入在 maxOccurs=1 的序列中定义的元素的重复项?

When processing XML that users generate, I will ignore any custom elements that they add via the <any> tag, but I want to to know if there is a way to enforce uniqueness of element names so that I can be sure that they're not putting in duplicates of elements defined in the sequence with maxOccurs=1?

这是一个示例 xsd(交互式版本 此处):

Here is a sample xsd (interactive version here):

<?xml version="1.0" encoding="utf-8"?>
<xsd:schema xmlns="testxsd" targetNamespace="testxsd" 
            xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
            elementFormDefault="qualified">
    <xsd:element name="XSDSequence">
        <xsd:complexType>
            <xsd:sequence>
                <xsd:element name="itemA" type="xsd:string"
                             minOccurs="1" maxOccurs="1"/>
                <xsd:element name="itemB" type="xsd:string"
                             minOccurs="0" maxOccurs="1"/>
                <xsd:element name="itemC" type="xsd:string"
                             minOccurs="1" maxOccurs="1"/>
                <xsd:any minOccurs="0" maxOccurs="unbounded" 
                         namespace="##any" processContents="lax"/>  
            </xsd:sequence>
        </xsd:complexType>
    </xsd:element>
</xsd:schema>

这里是一个通过 XSD 验证的示例 XML，但由于重复的 <itemA> 在末尾，我想出错:

and here is a sample XML that passes XSD validation but which I would like to error out on due to the duplicated <itemA> at the end:

<XSDSequence xmlns="testxsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <itemA>foo</itemA>
    <itemC>bar</itemC>
    <randomElement>this is ok</randomElement>
    <itemA>I want this second itemA to cause an error</itemA>
</XSDSequence>

(请注意，通过属性而不是元素捕获数据项不是我想做的事情.)

(Note that capturing data items via attributes rather than elements is not something that I want to do.)

推荐答案

不，在 XSD 1.0 中，一旦允许 任何 元素，就不能指定除 提供的约束之外的进一步约束code>minOccurs、maxOccurs、namespace 和 processContents.

No, in XSD 1.0, once you've allowed any element, you can't specify further constraints beyond those afforded by minOccurs, maxOccurs, namespace, and processContents.

在 XSD 1.1 中，您还可以针对 xsd:any 元素创建 xsd:assertions；你可以用断言来表达你的约束.[更新:不要错过 @C.M. Sperberg-McQueen 对 XSD 1.1 的简​​单想法:xsd:any/@notQName="itemA itemB itemC"]

In XSD 1.1, you can also make xsd:assertions against the xsd:any elements; you'd be able to express your constraint with an assertion. [Update: Don't miss @C. M. Sperberg-McQueen's simpler idea for XSD 1.1: xsd:any/@notQName="itemA itemB itemC"]

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