Question

i have generated a cs-classes with the xsd-tool from some xml scheme.
The scheme is a very complex scheme generated from uml-class descriptions.
Now I have written a simple test to ensure the functionality of the generated xsd-classes.
The test uses XmlSerializer to create the xml-file.

In my XSD-scheme there are some obligatory elements (definition with minocc=1 and maxocc=1 by xsd-default).

For example (simplified):

<xs:element name="order">
    <xs:complexType>
       ...
         <xs:element name="orderId" type="string"/>
         <xs:element name="material" type="Material"/>
       ...
    <xs:complexType>

Material is a complex type, which consists of several elements. It is part of order.

These elements should always exists in the resulting xml-file, even if they are empty or contains only empty elements. Now, if I serialize a class instance to an xml-file, only the elements appear where the class-propertys contain a value. If I set orderId the orderId-element appears, but not the material-element because in my class instance it’s null. As a result my xml-file is not valid to the xsd-schema.

Do you have an idea how i can validate the resulting xml-file with my xsd file during serialization? Is there a way to tell XmlSerializer that it should always generate obligatory elements (perhaps with a default value)?
Or is there a way to validate the structure of the class instance that should be serialized?

Answer 1

You cannot generate automatically elements to fulfill your required rules.
On your second question you can validate the generated xml with XmlReader and XmlSchema objects.
A small example would look like this:

        public IList<string> Validate(TextReader reader, XmlSchema schema)
        {
            XmlReaderSettings settings = new XmlReaderSettings();
            settings.Schemas.Add(schema);
            settings.ValidationType = ValidationType.Schema;

            List<string> errors = new List<string>();

            settings.ValidationEventHandler += (sender, e) =>
            {
                errors.Add(string.Format("Line {0} at position {1}{2}{3}",
                        e.Exception.LineNumber, e.Exception.LinePosition,
                                    Environment.NewLine, e.Message));
            };


            XmlReader xmlReader = XmlReader.Create(reader, settings);
            while (xmlReader.Read()) { };

            return errors;
        } 

This example takes a TextReader (can be a StreamReader, StringReader etc. ) and an XmlSchema object (you can construct one from the xsd file or whatever – check the documentation for it) and returns a list of validation errors.