Why is my XML validation failing against its schema?

Question

I need to validate a XML file against a schema. The XML file is being generated in code and before I save it I need to validate it to be correct.

I have stripped the problem down to its barest elements but am having an issue.

XML:

<?xml version="1.0" encoding="utf-16"?>
<MRIDSupportingData xmlns="urn:GenericLabData">
  <MRIDNumber>MRIDDemo</MRIDNumber>
  <CrewMemberIdentifier>1234</CrewMemberIdentifier>
  <PrescribedTestDate>1/1/2005</PrescribedTestDate>
</MRIDSupportingData>

Schema:

<?xml version="1.0" encoding="utf-16"?>
<xs:schema xmlns="urn:GenericLabData" targetNamespace="urn:GenericLabData" 
   xmlns:xs="http://www.w3.org/2001/XMLSchema">

   <xs:element name="MRIDSupportingData">
   <xs:complexType> 
      <xs:sequence>
        <xs:element name="MRIDNumber" type="xs:string" /> 
        <xs:element minOccurs="1" name="CrewMemberIdentifier" type="xs:string" />
      </xs:sequence>
   </xs:complexType>
  </xs:element>
</xs:schema>  

ValidationCode: (This code is from a simple app I wrote to test the validation logic. The XML and XSD files are stored on disk and are being read from there. In the actual app, the XML file would be in memory already as an XmlDocument object and the XSD would be read from an internal webserver.)

private void Validate()
{
  XmlReaderSettings settings = new XmlReaderSettings();
  settings.ValidationType = ValidationType.Schema;
  //settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessInlineSchema;
  //settings.ValidationFlags |= XmlSchemaValidationFlags.ProcessSchemaLocation;
  //settings.ValidationFlags |= XmlSchemaValidationFlags.ReportValidationWarnings;
  settings.ValidationEventHandler += new ValidationEventHandler(OnValidate);

  XmlSchemaSet schemas = new XmlSchemaSet();
  settings.Schemas = schemas;
  try
  {
    schemas.Add(null, schemaPathTextBox.Text);
    using (XmlReader reader = XmlReader.Create(xmlDocumentPathTextBox.Text, settings))
    {
      validateText.AppendLine("Validating...");
      while (reader.Read()) ;
      validateText.AppendLine("Finished Validating");
      textBox1.Text = validateText.ToString();
    }
  }
  catch (Exception ex)
  {
    textBox1.Text = ex.ToString();
  }

}

StringBuilder validateText = new StringBuilder();
private void OnValidate(object sender, ValidationEventArgs e)
{
  switch (e.Severity)
  {
    case XmlSeverityType.Error:
      validateText.AppendLine(string.Format("Error: {0}", e.Message));
      break;
    case XmlSeverityType.Warning:
      validateText.AppendLine(string.Format("Warning {0}", e.Message));
      break;
  }
}

When running the above code with the XML and XSD files defined above I get this output:

Validating... Error: The element 'MRIDSupportingData' in namespace 'urn:GenericLabData' has invalid child element 'MRIDNumber' in namespace 'urn:GenericLabData'. List of possible elements expected: 'MRIDNumber'. Finished Validating

What am I missing? As far as I can tell, MRIDNumber is MRIDNumber so why the error?

The actual XML file is much larger as well as the XSD, but it fails at the very beginning, so I have reduced the problem to almost nothing.

Any assistance on this would be great.

Thank you,
Keith

---

BTW, These files do work:

XML:

<?xml version='1.0'?>
<bookstore xmlns="urn:bookstore-schema">
  <book genre="novel">
    <title>The Confidence Man</title>
    <author>
      <first-name>Herman</first-name>
      <last-name>Melville</last-name>
    </author>
    <price>11.99</price>
  </book>
</bookstore>

Schema:

  <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns="urn:bookstore-schema"
    elementFormDefault="qualified"
    targetNamespace="urn:bookstore-schema">
  <xsd:element name="bookstore">
    <xsd:complexType>
      <xsd:sequence >
        <xsd:element name="book"  maxOccurs="unbounded">
          <xsd:complexType>
            <xsd:sequence >
              <xsd:element name="title" type="xsd:string"/>
              <xsd:element name="author">
                <xsd:complexType>
                  <xsd:sequence >
                    <xsd:element name="first-name"  type="xsd:string"/>
                    <xsd:element name="last-name" type="xsd:string"/>
                  </xsd:sequence> 
                </xsd:complexType>
              </xsd:element>
              <xsd:element name="price"  type="xsd:decimal"/>
            </xsd:sequence> 
            <xsd:attribute name="genre" type="xsd:string"/>
          </xsd:complexType>
        </xsd:element>
      </xsd:sequence>    
    </xsd:complexType>   
  </xsd:element>
</xsd:schema>

Answer 1

Try adding elementFormDefault="qualified" attribute in the xs:schema element of your XSD file.

I think the validator is saying that it wants a MRIDNumber element with no namespace, instead of your MRIDNumber element with namespace urn:GenericLabData.

Answer 2

In the small excerpt of XML/XSD you are currently testing, did you include PrescribedTestDate in the XSD as well?