XML Schema 如何通过枚举限制属性

XML Schema How to Restrict Attribute by Enumeration

提问by Luke

I have the following XML Tag

我有以下 XML 标签

<price currency="euros">20000.00</price>

How do I restrict the currency attribute to one the following:

如何将货币属性限制为以下之一：

• euros
• pounds
• dollars

• 欧元
• 磅
• 美元

AND the price to a double?

而且价格翻倍？

I just get an error when I try to a type on both, here's what I've got so far:

当我尝试在两者上输入一个类型时，我只是收到一个错误，这是我到目前为止所得到的：

<xs:element name="price">
    <xs:complexType>
        <xs:attribute name="currency">
            <xs:simpleType>
                <xs:restriction base="xs:string">
                    <xs:enumeration value="pounds" />
                    <xs:enumeration value="euros" />
                    <xs:enumeration value="dollars" />
                </xs:restriction>
            </xs:simpleType>
        </xs:attribute>
    </xs:complexType>
</xs:element>

回答by user998692

The numerical value seems to be missing from your price definition. Try the following:

您的价格定义中似乎缺少数值。请尝试以下操作：

<xs:simpleType name="curr">
  <xs:restriction base="xs:string">
    <xs:enumeration value="pounds" />
    <xs:enumeration value="euros" />
    <xs:enumeration value="dollars" />
  </xs:restriction>
</xs:simpleType>



<xs:element name="price">
        <xs:complexType>
            <xs:extension base="xs:decimal">
              <xs:attribute name="currency" type="curr"/>
            </xs:extension>
        </xs:complexType>
</xs:element>

回答by kjhughes

New answer to old question

旧问题的新答案

None of the existing answers to this old question address the real problem.

这个老问题的现有答案都没有解决真正的问题。

The real problemwas that xs:complexTypecannot directly have a xs:extensionas a child in XSD. The fix is to use xs:simpleContentfirst. Details follow...

真正的问题是xs:complexType不能xs:extension在 XSD 中直接将 a作为孩子。解决方法是先使用xs:simpleContent。详情如下...

---

---

Your XML,

你的 XML，

<price currency="euros">20000.00</price>

will be valid against eitherof the following corrected XSDs:

将适用于以下任一更正的 XSD：

Locally defined attribute type

本地定义的属性类型

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:element name="price">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:decimal">
          <xs:attribute name="currency">
            <xs:simpleType>
              <xs:restriction base="xs:string">
                <xs:enumeration value="pounds" />
                <xs:enumeration value="euros" />
                <xs:enumeration value="dollars" />
              </xs:restriction>
            </xs:simpleType>
          </xs:attribute>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
</xs:schema>

Globally defined attribute type

全局定义的属性类型

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:simpleType name="currencyType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="pounds" />
      <xs:enumeration value="euros" />
      <xs:enumeration value="dollars" />
    </xs:restriction>
  </xs:simpleType>

  <xs:element name="price">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="xs:decimal">
          <xs:attribute name="currency" type="currencyType"/>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
</xs:schema>

Notes

笔记

• As commented by @Paul, these do change the content type of pricefrom xs:stringto xs:decimal, but this is not strictly necessary and was not the real problem.
• As answered by @user998692, you could separate out the definition of currency, and you could change to xs:decimal, but this too was not the real problem.

• 正如评论说@保罗，这些做更改的内容类型 price，从xs:string到xs:decimal，但这不是绝对必要的，并没有真正的问题。
• 正如@user998692所回答的，您可以将货币的定义分开，您可以更改为xs:decimal，但这也不是真正的问题。

The real problemwas that xs:complexTypecannot directly have a xs:extensionas a child in XSD; xs:simpleContentis needed first.

真正的问题是在 XSD 中xs:complexType不能直接有xs:extension一个子项；xs:simpleContent首先需要。

A related matter (that wasn't asked but may have confused other answers):

一个相关的问题（没有被问到，但可能混淆了其他答案）：

How could pricebe restricted given that it has an attribute?

price鉴于它具有属性，如何限制？

In this case, a separate, global definition of priceTypewould be needed; it is not possible to do this with only local type definitions.

在这种情况下，需要一个单独的全局定义priceType；仅使用本地类型定义是不可能做到这一点的。

How to restrict element content when element has attribute

当元素具有属性时如何限制元素内容

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:simpleType name="priceType">  
    <xs:restriction base="xs:decimal">  
      <xs:minInclusive value="0.00"/>  
      <xs:maxInclusive value="99999.99"/>  
    </xs:restriction>  
  </xs:simpleType>

  <xs:element name="price">
    <xs:complexType>
      <xs:simpleContent>
        <xs:extension base="priceType">
          <xs:attribute name="currency">
            <xs:simpleType>
              <xs:restriction base="xs:string">
                <xs:enumeration value="pounds" />
                <xs:enumeration value="euros" />
                <xs:enumeration value="dollars" />
              </xs:restriction>
            </xs:simpleType>
          </xs:attribute>
        </xs:extension>
      </xs:simpleContent>
    </xs:complexType>
  </xs:element>
</xs:schema>

回答by A.B.Cade

you need to create a type and make the attribute of that type:

您需要创建一个类型并创建该类型的属性：

<xs:simpleType name="curr">
  <xs:restriction base="xs:string">
    <xs:enumeration value="pounds" />
    <xs:enumeration value="euros" />
    <xs:enumeration value="dollars" />
  </xs:restriction>
</xs:simpleType>

then:

然后：

<xs:complexType>
    <xs:attribute name="currency" type="curr"/>
</xs:complexType>

回答by Nachiket Kulkarni

<xs:element name="price" type="decimal">
<xs:attribute name="currency" type="xs:string" value="(euros|pounds|dollars)" /> 
</element> 

This would eliminate the need for enumeration completely. You could change type to double if required.

这将完全消除枚举的需要。如果需要，您可以将 type 更改为 double。