[Mono-list] Validating XML

Wed Apr 16 20:07:10 EDT 2008

I am working with XML and I looked at the C# Cookbook to see how to validate
XML and I ran across something similar to the following code:
using System;
using System.IO;
using System.Xml;
using System.Xml.Schema;

namespace Etro.RSchema2{

  public class RSchema2{
    public static void ValidateXml(string xmlFilename, string
validatorFilename,
                   ValidationType validationType){

      // Create a settings object for XML Document
      XmlReaderSettings settings = new XmlReaderSettings();
      settings.ValidationEventHandler += MyValidationEventHandler;
      settings.ValidationType = validationType;
      settings.Schemas.Add(null, validatorFilename);

      // Open the bookbad.xml file.
      if (settings.Schemas.Count > 0){
    using (XmlReader reader = XmlReader.Create(xmlFilename, settings)){
      // Replace validReader with reader for the whole loop.
      while (reader.Read()){
        if (reader.NodeType == XmlNodeType.Element){
          Console.Write("<{0}", reader.Name);
          while (reader.MoveToNextAttribute()) {
        Console.Write(" {0}='{1}'", reader.Name,
                  reader.Value);
          }
          Console.Write(">");
        }
        else if (reader.NodeType == XmlNodeType.Text){
          Console.Write(reader.Value);
        }else if (reader.NodeType == XmlNodeType.EndElement){
          Console.WriteLine("</{0}>", reader.Name);
        }
      }
    }
      }
    }

    private static void MyValidationEventHandler(object sender,
ValidationEventArgs e){
    Console.WriteLine("Validation Error Message: {0}", e.Message);
    Console.WriteLine("Validation Error Severity: {0}", e.Severity);
    if (e.Exception != null)
      {
        Console.WriteLine("Validation Error Line Number: {0}",
                  e.Exception.LineNumber);
        Console.WriteLine("Validation Error Line Position: {0}",
                  e.Exception.LinePosition);
        Console.WriteLine("Validation Error Source: {0}",
                  e.Exception.Source);
        Console.WriteLine("Validation Error Source Schema: {0}",
                  e.Exception.SourceSchemaObject);
        Console.WriteLine("Validation Error Source Uri: {0}",
                  e.Exception.SourceUri);
        Console.WriteLine("Validation Error thrown from: {0}",
                    e.Exception.TargetSite);
        Console.WriteLine("Validation Error callstack: {0}",
                  e.Exception.StackTrace);
      }
    }

    public static void Main(string[] args){
      // Check args
      if (args.Length < 2 || args.Length > 3){
    PrintUsage();
      }

      string xmlFile = string.Copy(args[0]);
      string validatorFile = string.Copy(args[1]);
      ValidationType validationType = ValidationType.Schema;

      // Check Validation type of Validator File
      if (args.Length == 3){
    if (args[2] == "schema"){
      validationType = ValidationType.Schema;
    }else if (args[2] == "dtd"){
      validationType = ValidationType.DTD;
    }
      }

      // Check that files exist
      CheckFile(xmlFile);
      CheckFile(validatorFile);
      ValidateXml(xmlFile, validatorFile, validationType);
    }

    // Utility Methods
    // Print Application Usage
    static void PrintUsage(){
      Console.WriteLine("usage:\n\tmono rschema1 xmlfile xsdfile");
      Environment.Exit(1);
    }

    // Check if file exists
    static void CheckFile(string fileName){
      if (!File.Exists(fileName)){
    Console.WriteLine("Could not locate {0}", fileName);
    Environment.Exit(1);
      }
    }
  }
}

When I run this code with a simple example such as note.xml and note.xsd

note.xml
-----------
<?xml version="1.0"?>
<note xmlns="file://home/aha/devel/cs/nshell/XmlSchemaReader">
  <to>Tove</to>
  <from>Jani</from>
  <heading>Reminder</heading>
  <body>Don't forget me this weekend</body>
  <boo>man</boo>
</note>

note.xsd
------------
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="file://home/aha/devel/cs/nshell/XmlSchemaReader"
xmlns="file://home/aha/devel/cs/nshell/XmlSchemaReader"
elementFormDefault="qualified">

<xs:element name="note">
  <xs:complexType>
    <xs:sequence>
      <xs:element name="to" type="xs:string"/>
      <xs:element name="from" type="xs:string"/>
      <xs:element name="heading" type="xs:string"/>
      <xs:element name="body" type="xs:string"/>
    </xs:sequence>
  </xs:complexType>
</xs:element>
</xs:schema>

I get the following output:

aha at pi:~/devel/cs/nshell/XmlSchemaReader$ mono rschema2.exe note.xml
note.xsd
<note xmlns='file://home/aha/devel/cs/nshell/XmlSchemaReader'><to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend</body>
Validation Error Message: XmlSchema error: Invalid start element:
file://home/aha/devel/cs/nshell/XmlSchemaReader:boo XML  Line 7, Position 4.
Validation Error Severity: Error
Validation Error Line Number: 7
Validation Error Line Position: 4
Validation Error Source:
Validation Error Source Schema:
Validation Error Source Uri:
Validation Error thrown from:
Validation Error callstack:
Validation Error Message: XmlSchema error: Element declaration for
file://home/aha/devel/cs/nshell/XmlSchemaReader:boo is missing. XML  Line 7,
Position 4.
Validation Error Severity: Error
Validation Error Line Number: 7
Validation Error Line Position: 4
Validation Error Source:
Validation Error Source Schema:
Validation Error Source Uri:
Validation Error thrown from:
Validation Error callstack:
<boo>man</boo>
Validation Error Message: XmlSchema error: Invalid end element. There are
still required content items. XML  Line 8, Position 3.
Validation Error Severity: Error
Validation Error Line Number: 8
Validation Error Line Position: 3
Validation Error Source:
Validation Error Source Schema:
Validation Error Source Uri:
Validation Error thrown from:
Validation Error callstack:
</note>

Why am I seeing the output of the error three times?
Likewise if I put the invalid element at the beginning I receive errors
about valid elements.

Regards
-- 
Aquil H. Abdullah
aquil.abdullah at gmail.com
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