XML validation

XML validation is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Given an XML document and an XSD schema definition validate that the document follows the schema described.

C#

<lang csharp> using System; using System.Xml; using System.Xml.Schema; using System.IO;

public class Test { public static void Main() { // your code goes here XmlSchemaSet sc = new XmlSchemaSet(); sc.Add(null, "http://venus.eas.asu.edu/WSRepository/xml/Courses.xsd"); XmlReaderSettings settings = new XmlReaderSettings(); settings.ValidationType = ValidationType.Schema; settings.Schemas = sc; settings.ValidationEventHandler += new ValidationEventHandler(ValidationCallBack); // Create the XmlReader object. XmlReader reader = XmlReader.Create("http://venus.eas.asu.edu/WSRepository/xml/Courses.xml", settings); // Parse the file. while (reader.Read()); // will call event handler if invalid Console.WriteLine("The XML file is valid for the given xsd file"); }

// Display any validation errors. private static void ValidationCallBack(object sender, ValidationEventArgs e) { Console.WriteLine("Validation Error: {0}", e.Message); } } </lang>

F#

Using an inline stylesheet:

<lang fsharp>open System.Xml open System.Xml.Schema open System.IO

let xml = @"<root> <xs:schema id='an-element' targetNamespace='example' xmlns:mstns='example' xmlns='example' xmlns:xs='http://www.w3.org/2001/XMLSchema' attributeFormDefault='unqualified' elementFormDefault='qualified'>

 <xs:element name='an-element'>
   <xs:complexType>
     <xs:sequence minOccurs='0' maxOccurs='unbounded'>
       <xs:element name='another-element' nillable='true'>
         <xs:complexType>
           <xs:simpleContent>
             <xs:extension base='xs:string'>
               <xs:attribute name='an-attribute' form='unqualified' type='xs:boolean' />
             </xs:extension>
           </xs:simpleContent>
         </xs:complexType>
       </xs:element>
     </xs:sequence>
   </xs:complexType>
 </xs:element>

</xs:schema> <an-element xmlns='example'>

   <another-element an-attribute='false'>...</another-element>
   <another-element an-attribute='wrong'>123</another-element>

</an-element> </root>"

let validationData withWarnings =

   let errors = ref 0
   let warnings = ref 0
   fun input ->
       match input with
       | Some(msg, severity) ->
           if severity = XmlSeverityType.Error then
               errors := !errors + 1
               printfn "Validation error: %s" msg
           elif withWarnings then
               warnings := !warnings + 1
               printfn "Validation warning: %s" msg
           None
       | None ->
           if withWarnings then
               Some(dict[XmlSeverityType.Error, !errors; XmlSeverityType.Warning, !warnings])
           else
               Some(dict[XmlSeverityType.Error, !errors])

[<EntryPoint>] let main argv =

   let withWarnings = argv.Length > 0 && argv.[0] = "-w"
   let vData = validationData withWarnings
   let validationEvent = new ValidationEventHandler(fun _ e ->
       vData (Some(e.Message, e.Severity)) |> ignore)
   let settings = new XmlReaderSettings()
   settings.ValidationType <- ValidationType.Schema
   settings.ValidationEventHandler.AddHandler(validationEvent)
   settings.ValidationFlags <- settings.ValidationFlags ||| XmlSchemaValidationFlags.ProcessInlineSchema ||| XmlSchemaValidationFlags.ReportValidationWarnings
   let reader = XmlReader.Create(new StringReader(xml), settings);
   while reader.Read() do ()
   printfn "%A" (Seq.toList (vData None).Value)
   0

</lang>

Output:

>RosettaCode
Validation error: The 'an-attribute' element is invalid - The value 'wrong' is invalid according to its datatype 'http://www.w3.org/2001/XMLSchema:boolean' - The string 'wrong' is not a valid boolean value.
[[Error, 1]]

>RosettaCode -w
Validation warning: Could not find schema information for the element 'root'.
Validation error: The 'an-attribute' element is invalid - The value 'wrong' is invalid according to its datatype 'http://www.w3.org/2001/XMLSchema:boolean' - The string 'wrong' is not a valid boolean value.
[[Error, 1]; [Warning, 1]]

Changing wrong to a boolean, e. g. true, The result (without -w) is

[[Error, 0]]

Java

<lang java>import static javax.xml.XMLConstants.W3C_XML_SCHEMA_NS_URI;

import java.net.MalformedURLException; import java.net.URL;

import javax.xml.transform.stream.StreamSource; import javax.xml.validation.SchemaFactory; import javax.xml.validation.Validator; import javax.xml.ws.Holder;

import org.xml.sax.ErrorHandler; import org.xml.sax.SAXException; import org.xml.sax.SAXParseException;

public class XmlValidation { public static void main(String... args) throws MalformedURLException { URL schemaLocation = new URL("http://venus.eas.asu.edu/WSRepository/xml/Courses.xsd"); URL documentLocation = new URL("http://venus.eas.asu.edu/WSRepository/xml/Courses.xml"); if (validate(schemaLocation, documentLocation)) { System.out.println("document is valid"); } else { System.out.println("document is invalid"); } }

// The least code you need for validation public static boolean minimalValidate(URL schemaLocation, URL documentLocation) { SchemaFactory factory = SchemaFactory.newInstance(W3C_XML_SCHEMA_NS_URI); try { Validator validator = factory.newSchema(schemaLocation).newValidator(); validator.validate(new StreamSource(documentLocation.toString())); return true; } catch (Exception e) { return false; } }

// A more complete validator public static boolean validate(URL schemaLocation, URL documentLocation) { SchemaFactory factory = SchemaFactory.newInstance(W3C_XML_SCHEMA_NS_URI); final Holder<Boolean> valid = new Holder<>(true); try { Validator validator = factory.newSchema(schemaLocation).newValidator(); // Get some better diagnostics out validator.setErrorHandler(new ErrorHandler(){ @Override public void warning(SAXParseException exception) { System.out.println("warning: " + exception.getMessage()); }

@Override public void error(SAXParseException exception) { System.out.println("error: " + exception.getMessage()); valid.value = false; }

@Override public void fatalError(SAXParseException exception) throws SAXException { System.out.println("fatal error: " + exception.getMessage()); throw exception; }}); validator.validate(new StreamSource(documentLocation.toString())); return valid.value; } catch (SAXException e) { // Already reported above return false; } catch (Exception e) { // If this is the only thing that throws, it's a gross error System.err.println(e); return false; } } }</lang>

Python

<lang python>#!/bin/python from __future__ import print_function import lxml from lxml import etree

if __name__=="__main__":

parser = etree.XMLParser(dtd_validation=True) schema_root = etree.XML(\ <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:element name="a" type="xsd:integer"/> </xsd:schema> ) schema = etree.XMLSchema(schema_root)

#Good xml parser = etree.XMLParser(schema = schema) try: root = etree.fromstring("<a>5</a>", parser) print ("Finished validating good xml") except lxml.etree.XMLSyntaxError as err: print (err)

#Bad xml parser = etree.XMLParser(schema = schema) try: root = etree.fromstring("<a>5foobar</a>", parser) except lxml.etree.XMLSyntaxError as err: print (err)</lang>

Output:

Finished validating good xml
Element 'a': Element content is not allowed, because the type definition is simple.