什么 xsd 会让一个元素无限地拥有自己作为子元素? [英] What xsd will let an element have itself as a sub element infinitely?
问题描述
如何创建一个 xsd 来给我这种可以无限运行的 xml 结构?
How can I create an xsd to give me this type of xml structure that can go on infinitely?
<?xml version="1.0" encoding="utf-8" ?>
<SampleXml>
<Items>
<Item name="SomeName" type="string">
This would be the value
</Item>
<Item name="SecondName" type="string">
This is the next string
</Item>
<Item name="AnotherName" type="list">
<Items>
<Item name="SubName" type="string">
A string in a sub list
</Item>
<Item name="SubSubName" type="list">
<Items>
<Item name="HowDoI" type="string">
How do I keep this going infinately?
</Item>
</Items>
</Item>
</Items>
</Item>
</Items>
</SampleXml>
我找到的唯一解决方案是在 xsd 中重复我愿意复制的次数.如下所示.
The only solution I have found has been to just repeat in the xsd as many times as I am willing to copy. Like below.
<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="SampleXml">
<xs:complexType>
<xs:sequence>
<xs:element name="Items">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded" name="Item">
<xs:complexType mixed="true">
<xs:sequence minOccurs="0">
<xs:element name="Items">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded" name="Item">
<xs:complexType mixed="true">
<xs:sequence minOccurs="0">
<xs:element name="Items">
<xs:complexType>
<xs:sequence>
<xs:element name="Item">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute name="name" type="xs:string" use="required" />
<xs:attribute name="type" type="xs:string" use="required" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="name" type="xs:string" use="required" />
<xs:attribute name="type" type="xs:string" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="name" type="xs:string" use="required" />
<xs:attribute name="type" type="xs:string" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
推荐答案
使用 <xs:element ref="bla"/> 递归引用元素.一个简单的例子:
Use <xs:element ref="bla" /> to recursively refer to the elements.
A simple example:
<xs:element name="recursive">
<xs:complexType>
<xs:sequence>
<xs:element ref="recursive" minOccurs="0" maxOccurs="unbounded" />
</xs:sequence>
</xs:complexType>
</xs:element>
允许你写这个:
<recursive>
<recursive>
<recursive />
</recursive>
<recursive />
<recursive>
<recursive>
<recursive />
</recursive>
</recursive>
</recursive>
ref"属性的使用也极大地有助于提高 XSD 的可读性.我会这样写你的:
Usage of the 'ref' attribute also helps greatly in increasing the readability of your XSD. This is how I would write yours:
<?xml version="1.0" encoding="utf-8"?>
<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="SampleXml">
<xs:complexType>
<xs:sequence>
<xs:element ref="Items" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Items">
<xs:complexType>
<xs:sequence>
<xs:element ref="Item" maxOccurs="unbounded" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Item">
<xs:complexType mixed="true">
<xs:sequence>
<xs:element ref="Items" minOccurs="0" />
</xs:sequence>
<xs:attribute name="name" type="xs:string" use="required" />
<xs:attribute name="type" type="xs:string" use="required" />
</xs:complexType>
</xs:element>
</xs:schema>
请注意，即使在并非绝对必要的情况下(例如 SampleXml 引用 Items 时)，使用 'ref' 也会减少 XSD 的嵌套混乱并且更具可读性.
Note how use of 'ref' even when it's not strictly necessary (such as when SampleXml refers to Items) makes the XSD less of a nested mess and more readable.
这篇关于什么 xsd 会让一个元素无限地拥有自己作为子元素?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
