Validating XML: No matching global declaration available for the validation root

libxml2, ruby, xml, xsd

Solution

It's a cryptic error, but it's probably because your XSD is malformed. For example, the contents of the channel, hotel (both the inner and outer elements), room, and request `xsd:element` tags should all be wrapped in `xsd:complexType` tags. Also, `use` is only valid on `xsd:attribute`, not `xsd:element`. For elements, use minOccurs and maxOccurs (although both default to 1, so they aren't actually necessary in this case). In addition, your outer hotel element contains a room element, which must contain a hotel element, creating an infinite loop. Further, you don't name your username and password elements properly. Finally, that inner hotel element should probably be date. Here's what I think you're looking for:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">

  <!-- channel -->
  <xsd:element name="channel">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element name="username" type="xsd:string"/>
        <xsd:element name="password" type="xsd:string"/>
      </xsd:sequence>
      <xsd:attribute name="name" use="required" type="xsd:string" />
    </xsd:complexType>
  </xsd:element>

  <!-- hotel -->
  <xsd:element name="hotel">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element name="date">
          <xsd:complexType>
            <xsd:attribute name="from" use="required" type="xsd:string" />
            <xsd:attribute name="to" use="required" type="xsd:string" />
          </xsd:complexType>
        </xsd:element>
        <xsd:element ref="room" minOccurs="1"/>
      </xsd:sequence>
      <xsd:attribute name="id" use="required" type="xsd:string" />
    </xsd:complexType>
  </xsd:element>


  <!-- room -->
  <xsd:element name="room">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element name="allocation" type="xsd:string"></xsd:element>
      </xsd:sequence>
      <xsd:attribute name="id" use="required" type="xsd:string" />
    </xsd:complexType>
  </xsd:element>

  <!-- building all together -->
  <xsd:element name="request">
    <xsd:complexType>
      <xsd:sequence>
        <xsd:element ref="channel" maxOccurs="1"/>
        <xsd:element ref="hotel" maxOccurs="1"/>
      </xsd:sequence>
    <xsd:attribute name="type" use="required" type="xsd:string" />
    </xsd:complexType>
  </xsd:element>
</xsd:schema>

Problem

Original source