How to: Validate Using XSD (LINQ to XML)

The System.Xml.Schema namespace contains extension methods that make it easy to validate an XML tree against an XML Schema Definition Language (XSD) file. For more information, see the Validate method documentation.

The following example creates an XmlSchemaSet, then validates two XDocument objects against the schema set. One of the documents is valid, the other is not.

string xsdMarkup =
    @"<xsd:schema xmlns:xsd='http://www.w3.org/2001/XMLSchema'>
       <xsd:element name='Root'>
        <xsd:complexType>
         <xsd:sequence>
          <xsd:element name='Child1' minOccurs='1' maxOccurs='1'/>
          <xsd:element name='Child2' minOccurs='1' maxOccurs='1'/>
         </xsd:sequence>
        </xsd:complexType>
       </xsd:element>
      </xsd:schema>";
XmlSchemaSet schemas = new XmlSchemaSet();
schemas.Add("", XmlReader.Create(new StringReader(xsdMarkup)));

XDocument doc1 = new XDocument(
    new XElement("Root",
        new XElement("Child1", "content1"),
        new XElement("Child2", "content1")
    )
);

XDocument doc2 = new XDocument(
    new XElement("Root",
        new XElement("Child1", "content1"),
        new XElement("Child3", "content1")
    )
);

Console.WriteLine("Validating doc1");
bool errors = false;
doc1.Validate(schemas, (o, e) =>
                     {
                         Console.WriteLine("{0}", e.Message);
                         errors = true;
                     });
Console.WriteLine("doc1 {0}", errors ? "did not validate" : "validated");

Console.WriteLine();
Console.WriteLine("Validating doc2");
errors = false;
doc2.Validate(schemas, (o, e) =>
                     {
                         Console.WriteLine("{0}", e.Message);
                         errors = true;
                     });
Console.WriteLine("doc2 {0}", errors ? "did not validate" : "validated");

This example produces the following output:

Validating doc1
doc1 validated

Validating doc2
The element 'Root' has invalid child element 'Child3'. List of possible elements expected: 'Child2'.
doc2 did not validate

The following example validates that the XML document from Sample XML File: Customers and Orders (LINQ to XML) is valid per the schema from Sample XSD File: Customers and Orders. It then modifies the source XML document. It changes the CustomerID attribute on the first customer. After the change, orders will then refer to a customer that does not exist, so the XML document will no longer validate.

This example uses the following XML document: Sample XML File: Customers and Orders (LINQ to XML).

This example uses the following XSD schema: Sample XSD File: Customers and Orders.

XmlSchemaSet schemas = new XmlSchemaSet();
schemas.Add("", "CustomersOrders.xsd");

Console.WriteLine("Attempting to validate");
XDocument custOrdDoc = XDocument.Load("CustomersOrders.xml");
bool errors = false;
custOrdDoc.Validate(schemas, (o, e) =>
                     {
                         Console.WriteLine("{0}", e.Message);
                         errors = true;
                     });
Console.WriteLine("custOrdDoc {0}", errors ? "did not validate" : "validated");

Console.WriteLine();
// Modify the source document so that it will not validate.
custOrdDoc.Root.Element("Orders").Element("Order").Element("CustomerID").Value = "AAAAA";
Console.WriteLine("Attempting to validate after modification");
errors = false;
custOrdDoc.Validate(schemas, (o, e) =>
                     {
                         Console.WriteLine("{0}", e.Message);
                         errors = true;
                     });
Console.WriteLine("custOrdDoc {0}", errors ? "did not validate" : "validated");

This example produces the following output:

Attempting to validate
custOrdDoc validated

Attempting to validate after modification
The key sequence 'AAAAA' in Keyref fails to refer to some key.
custOrdDoc did not validate
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