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XML Validation

From Rosetta Code
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.


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, "");
XmlReaderSettings settings = new XmlReaderSettings();
settings.ValidationType = ValidationType.Schema;
settings.Schemas = sc;
settings.ValidationEventHandler += new ValidationEventHandler(ValidationCallBack);
// Create the XmlReader object.
XmlReader reader = XmlReader.Create("", 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);


Using an inline stylesheet:

open System.Xml
open System.Xml.Schema
open System.IO
let xml = @"<root>
<!--Start of schema-->
<xs:schema id='an-element' targetNamespace='example' xmlns:mstns='example' xmlns='example' xmlns:xs='' attributeFormDefault='unqualified' elementFormDefault='qualified'>
<xs:element name='an-element'>
<xs:sequence minOccurs='0' maxOccurs='unbounded'>
<xs:element name='another-element' nillable='true'>
<xs:extension base='xs:string'>
<xs:attribute name='an-attribute' form='unqualified' type='xs:boolean' />
<!--End of schema-->
<an-element xmlns='example'>
<another-element an-attribute='false'>...</another-element>
<another-element an-attribute='wrong'>123</another-element>

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 ->
if withWarnings then
Some(dict[XmlSeverityType.Error, !errors; XmlSeverityType.Warning, !warnings])
Some(dict[XmlSeverityType.Error, !errors])
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.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)
Validation error: The 'an-attribute' element is invalid - The value 'wrong' is invalid according to its datatype '' - 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 '' - 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]]


import static javax.xml.XMLConstants.W3C_XML_SCHEMA_NS_URI;
import javax.xml.validation.SchemaFactory;
import javax.xml.validation.Validator;
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("");
URL documentLocation = new URL("");
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(){
public void warning(SAXParseException exception) {
System.out.println("warning: " + exception.getMessage());
public void error(SAXParseException exception) {
System.out.println("error: " + exception.getMessage());
valid.value = false;
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
return false;


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="">
<xsd:element name="a" type="xsd:integer"/>
schema = etree.XMLSchema(schema_root)
#Good xml
parser = etree.XMLParser(schema = schema)
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)
root = etree.fromstring("<a>5<b>foobar</b></a>", parser)
except lxml.etree.XMLSyntaxError as err:
print (err)
Finished validating good xml
Element 'a': Element content is not allowed, because the type definition is simple.