CODEWITHSUNDEEP
xsdxml-validation
Michiel van Oosterhout
Michiel van Oosterhout

Reputation: 23084

Can I require an XML attribute to have a value?

This is (part of) the XML that I want to define in my schema. I have already added a unique constraint for the name attribute of the <add /> element.

<parameters>
  <add name="one" value="1" />
  <add name="two" value="2" />
</parameters>

But I don't know how to prevent <add name="" value="" />. I have tried the following schema, but it's not honored:

<xs:attribute name="name" use="required" type="config:NonEmptyString" />

<xs:simpleType name="NonEmptyString">
  <xs:restriction base="xs:string">
    <xs:minLength value="1" />
  </xs:restriction>
</xs:simpleType>

config is the target namespace for the schema.

Edit: I'm using Visual Studio to validate XML as I write it in the XML editor.

Upvotes: 0

Views: 625

Answers (2)

MiMo
MiMo

Reputation: 11953

Visual Studio 2010 does the validation correctly - it produces the warning:

Warning 4 The 'name' attribute is invalid - The value '' is invalid according to its datatype 'config:NonEmptyString' - The actual length is less than the MinLength value. XMLFile1.xml    3   14  Miscellaneous Files

but for some reason (bug?) it does not underline the error position in the XML editor.

Upvotes: 1

Petru Gardea
Petru Gardea

Reputation: 21638

I did a quick test; created an XSD out of the XML and added your constraint:

<?xml version="1.0" encoding="utf-8"?>
<!--XML Schema generated by QTAssistant/XML Schema Refactoring (XSR) Module (http://www.paschidev.com)-->
<xsd:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <xsd:element name="parameters">
        <xsd:complexType>
            <xsd:sequence>
                <xsd:element maxOccurs="unbounded" name="add">
                    <xsd:complexType>
                        <xsd:attribute name="name" type="NonEmptyString" use="required"/>
                        <xsd:attribute name="value" type="xsd:unsignedByte" use="required"/>
                    </xsd:complexType>
                </xsd:element>
            </xsd:sequence>
        </xsd:complexType>
    </xsd:element>
    <xsd:simpleType name="NonEmptyString">
        <xsd:restriction base="xsd:string">
            <xsd:minLength value="1"/>
        </xsd:restriction>
    </xsd:simpleType>
</xsd:schema>

I've validated this XML:

<parameters>
  <add name="" value="1" />
  <add name="two" value="2" />
</parameters>

And I've got this error:

Error occurred while loading [], line 2 position 8
The 'name' attribute is invalid - The value '' is invalid according to its datatype 'NonEmptyString' - The actual length is less than the MinLength value.

I would say that the problem is rather with your XSD processor, as opposed to the XSD itself. Maybe you could update the post with the processor you're using?

Upvotes: 2

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