FUNcLogs: XML Schema 從看不懂到慢慢懂

這邊用很快的速度介紹屬性(Attribute)，屬性的宣告和simple element 是一樣的，所以其他廢話就不多說了。值得注意的是，在XML裡，物件的屬性都是非必要的，如果是必要屬性，則須加上use="required"。

例如以下語法，就代表lang 這個屬性是必要的：

<xs:attribute name="lang" type="xs:string" use="required"/>

Restrictions

接下來是有點無聊的限制(Restrictions)，可以告訴XML 某個數值的限制，例如得分最大不能超過100，最小不能小於0。

就可以用以下Schema 限制：

<xs:element name="score">

<xs:simpleType>

<xs:restriction base="xs:integer">

<xs:minInclusive value="0"/>

<xs:maxInclusive value="100"/>

</xs:restriction>

</xs:simpleType>

</xs:element>

好…費話不多說(因為再多說對速成也許沒幫助)，這邊列出原文中可以用在限制的內容：

Constraint	Description
enumeration	Defines a list of acceptable values
fractionDigits	Specifies the maximum number of decimal places allowed. Must be equal to or greater than zero
length	Specifies the exact number of characters or list items allowed. Must be equal to or greater than zero
maxExclusive	Specifies the upper bounds for numeric values (the value must be less than this value)
maxInclusive	Specifies the upper bounds for numeric values (the value must be less than or equal to this value)
maxLength	Specifies the maximum number of characters or list items allowed. Must be equal to or greater than zero
minExclusive	Specifies the lower bounds for numeric values (the value must be greater than this value)
minInclusive	Specifies the lower bounds for numeric values (the value must be greater than or equal to this value)
minLength	Specifies the minimum number of characters or list items allowed. Must be equal to or greater than zero
pattern	Defines the exact sequence of characters that are acceptable
totalDigits	Specifies the exact number of digits allowed. Must be greater than zero
whiteSpace	Specifies how white space (line feeds, tabs, spaces, and carriage returns) is handled

英文也很好懂…我就不逐字翻譯了。

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