The saxon:validate-type pragma

Saxon-EE provides a pragma (a language extension) to allow constructed elements to be validated against a schema-defined global type definition. The standard validate expression allows validation only against a global element declaration, but some schemas (an example is FpML) provide very few global elements, and instead rely heavily on locally-declared elements having a global type. This makes it impossible to construct fragments of an FpML document in a way that takes advantage of static and dynamic type checking.

The extension takes the form:

Conceptually, it makes a copy of the result of evaluating expr and validates it against the named schema type, causing the copied nodes to acquire type annotations based on the validation process. The effect is the same as that of the type attribute in XSLT instructions such as xsl:element and xsl:copy-of. The schema type (shown in the above example as myPersonType) may be a simple type or a complex type defined in an imported schema, or a built-in type; it is written as a QName, using the default namespace for elements and types if it is unprefixed.

Note that XQuery processors other than Saxon will typically ignore this pragma, and return the value of expr unchanged. Such processors will report type-checking failures if the value is used in a context where the required type is element(*, type-name).

You can use a different namespace prefix in place of saxon, but it must be bound using a namespace declaration to the namespace "http://saxon.sf.net/".

Here is a complete example:

Saxon ignores any pragmas in a namespace other than the Saxon namespace; it rejects any pragmas whose QName is ill-formed, as well as pragmas in the Saxon namespace whose local name is not recognized.

The construct also allows validation of attributes against a simple type definition, for example: