Saxon Documentation

Full Contents

About Saxon

Changes in this Release

Licensing

Using XSLT 2.0

Using XQuery

Handling Source Documents

XML Schema Processing

XPath API for Java

Saxon on .NET

Extensibility

Saxon Extensions
	Introduction
	EXSLT Extensions
	Extension attributes (XSLT only)
	Additional serialization parameters
	Extension functions
»	Extension instructions

Sample Saxon Applications

The Saxon SQL Extension

XSLT Elements

XPath 2.0 Expression Syntax

Function Library

Standards Conformance

saxon:catch

This instruction is always used together with saxon:try. It is used to catch dynamic errors occurring within a saxon:try instruction, and to return an alternative result when an error occurs.

The parent instruction must be saxon:try. A saxon:try element must have at least one saxon:catch child element (there may be several), and the saxon:catch children must come last, except perhaps for any xsl:fallback children.

There is a mandatory attribute errors defining which errors are caught. Every error code is identified by a QName. The attribute is a whitespace-separated list of NameTests which are used to match this QName. Each NameTest may be in the form * (match all names), *:local (match local within any namespace), err:* (match all names in namespace err, or err:ABCD9867 (match a specific error code). The most common namespace, used by all system-defined errors, is http://www.w3.org/2005/xqt-errors, for which the conventional prefix is err:.

The value to be returned by the saxon:catch element may be calculated in an XPath expression in the select attribute, or in instructions forming the body of the saxon:catch element.

Within the select expression, or within the body of the saxon:catch element, the following variables are available. The namespace prefix err in this names must be bound to the namespace URI http://www.w3.org/2005/xqt-errors.

Variable	Type	Value
err:code	xs:QName	The error code
err:description	xs:string	A description of the error condition
err:value	item()*	Value associated with the error. For an error raised by calling the `error` function, this is the value of the third argument (if supplied). For an error raised by evaluating `xsl:message` with `terminate="yes"`, this is the document node at the root of the tree containing the XML message body.
err:module	xs:string?	The URI (or system ID) of the stylesheet module containing the instruction where the error occurred; an empty sequence if the information is not available.
err:line-number	xs:integer?	The line number within the stylesheet module of the instruction where the error occurred; an empty sequence if the information is not available.
err:column-number	xs:integer?	The column number within the stylesheet module of the instruction where the error occurred; an empty sequence if the information is not available.

The catch block can throw a new error by calling the error() function.

Variables declared within the saxon:try block are not visible within the saxon:catch block.

For examples, see saxon:try.