XML模式：具有仅包含“受限”文本的属性的元素

Question

I want to define an element with some restricted text and an attribute

<some_element my_attr="data">some restricted text</some_element>

How can I create an element like this?

I tried:

<complexType>
    <simpleContent>
        <restriction base="string">
            <pattern value="AAA"></pattern>
            <attribute name="newattr" type="string"></attribute>
        </restriction>
    </simpleContent>
</complexType>

But getting error msg:

Complex Type Definition Representation Error for type '#AnonType_childparent'. When is used, the base type must be a complexType whose content type is simple, or, only if restriction is specified, a complex type with mixed content and emptiable particle, or, only if extension is specified, a simple type. 'string' satisfies none of these conditions.

And then tried something like this

<complexType>
    <complexContent>
        <extension base="string">
            <attribute name="attr" type="string"></attribute>
        </extension>
    </complexContent>
</complexType>

This time error was (This time I didn't add any restriction; this was for test purpose only):

Complex Type Definition Representation Error for type '#AnonType_childparent'. When is used, the base type must be a complexType. 'string' is a simpleType.

I am not getting clearly what the errors are implying? Is there some better explanation of error text available?

Answer 1

Your question is more or less a duplicate of this question (just answered it).

Think in these terms:

• if your element has attributes and/or nested elements, it must be a complex type.
• if your element can have text, but no markup (nested elements) then it must be of simpleContent
• simpleContent can only be extended from a simple type (if you need to add an attribute). If you need additional constraints on the simple type, you need to specifically create a new simple type, restricting the base type, then extend that in a simple content.

This post on SO shows you an end-to-end example, of the above explanation. For your particular case:

<?xml version="1.0" encoding="utf-8" ?>
<!-- XML Schema generated by QTAssistant/XSD Module (http://www.paschidev.com) -->
<xsd:schema elementFormDefault="qualified" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <xsd:simpleType name="tSomeRestrictedText">
        <xsd:restriction base="xsd:string">
            <xsd:pattern value="AAA"/>
        </xsd:restriction>
    </xsd:simpleType>
    <xsd:element name="some_element">
        <xsd:complexType>
            <xsd:simpleContent>
                <xsd:extension base="tSomeRestrictedText">
                    <xsd:attribute name="my_attr" type="xsd:string"/>
                </xsd:extension>
            </xsd:simpleContent>
        </xsd:complexType>
    </xsd:element>
</xsd:schema>