How to validate xml code file though .NET? + How would I do it if I use XML serialization?

Question

I want users to be able to export data as an XML file. Of course I want them to be able to later on import that same XML file however they always could change it or it could be a different XML file.

So I want to validate the XML file to check if it is in the format that I expect. So I guess I would need something like a schema to check just that it has to be through code.

So if I expect

<Root>
 <Something>
    <SomethingElse> </SomethingElse>
 </Something>
</Root>

I don't want some other format to be in the file other then the one I expect.

Also how would I validate fields? Like say I require that there must be some text in between tags. If it is blank the file is not valid.

So how could I do this?

Edit

I decided to use XML serialization so I know it will through an exception if it is the wrong format and ignore stuff that does not work. However I am not sure should I just go through it and C# to validate each of the records or should I try to make an xml schema to do it.

If I would want to do it through an xml schema with xml serialization how would that work? Like Do I first do something like I seen in the responses then de serialize it? Or how would I do it?

Answer 1

Here's a code snippet that you can use to do so:

using (FileStream stream = File.OpenRead(xsdFilepath))
{
    XmlReaderSettings settings = new XmlReaderSettings();

    XmlSchema schema = XmlSchema.Read(stream, OnXsdSyntaxError);
    settings.ValidationType = ValidationType.Schema;
    settings.Schemas.Add(schema);
    settings.ValidationEventHandler += OnXmlSyntaxError;

    using (XmlReader validator = XmlReader.Create(xmlPath, settings))
    {
        // Validate the entire xml file
        while (validator.Read()) ;
    }
}

The OnXmlSyntaxError function will be called when a syntax error occur.

Answer 2

There are a few ways to validate XML files. Check out How To Validate an XML Document by Using DTD, XDR, or XSD in Visual C# .NET

Also see Validating an XML against Referenced XSD in C# example

Another good example is Validate XML against XSD using code at runtime in C#

Here is the code from the last post:

public void ValidateXmlDocument(
    XmlReader documentToValidate, string schemaPath)
{
    XmlSchema schema;
    using (var schemaReader = XmlReader.Create(schemaPath))
    {
        schema = XmlSchema.Read(schemaReader, ValidationEventHandler);
    }

    var schemas = new XmlSchemaSet();
    schemas.Add(schema);

    var settings = new XmlReaderSettings();
    settings.ValidationType = ValidationType.Schema;
    settings.Schemas = schemas;
    settings.ValidationFlags =
        XmlSchemaValidationFlags.ProcessIdentityConstraints |
        XmlSchemaValidationFlags.ReportValidationWarnings;
    settings.ValidationEventHandler += ValidationEventHandler;

    using (var validationReader = XmlReader.Create(documentToValidate, 
           settings))
    {
        while (validationReader.Read()) { }
    }
}

private static void ValidationEventHandler(
    object sender, ValidationEventArgs args)
{
    if (args.Severity == XmlSeverityType.Error)
    {
        throw args.Exception;
    }
    Debug.WriteLine(args.Message);
}

Answer 3

You can use LINQ to XML: http://msdn.microsoft.com/en-us/library/bb387037.aspx. This page also shows how to do that along with source to dump any invalid nodes: http://blogs.msdn.com/xmlteam/archive/2007/03/03/the-new-linq-to-xml-bridge-classes-to-system-xml.aspx

Answer 4

Validate XML file with Schema in .NET

Answer 5

You can use xml serialization in your classes:

[XmlType("Root", Namespace = "http://example.com/Root")]
[XmlRoot(Namespace = "http://example.com/Root.xsd", ElementName = "Root", IsNullable = false)]
public class Root {
  [XmlElement("Something")] 
  public Something Something { get; set; }
}

public class Something {
  [XmlElement("SomethingElse")]
  public SomethingElse SomethingElse { get; set; }
}

public class SomethingElse {
  [XmlText]
  public string Text { get; set; }
}

Serialize it like this:

var serializer = new XmlSerializer(typeof(Root));
serializer.Serialize(outputStrem, myRoot);

You can then test before deserializing, e.g.:

var serializer = new XmlSerializer(typeof(Root));
string xml = @"
  <Root xmlns='http://example.com/Root'>
    <Something>
      <SomethingElse>Yep!</SomethingElse>
    </Something>
  </Root>"; // remember to use the XML namespace!
Debug.Assert(serializer.CanDeserialize(new XmlTextReader(new StringReader(xml))));

And then to deserialize simply:

Root newRoot = (Root)serializer.Deserialize(inputStream);

Your XSD is implicit. It matches your classes. To use richer XSDs, you can venture into Schema Providers.