xml::schematron::xpath(3)

NAME

XML::Schematron::XPath - Perl extension for validating XML
with XPath expressions.

SYNOPSIS

use XML::Schematron::XPath;
my  $pseudotron  = XML::Schematron::XPath->new(schema =>
'my_schema.xml');
my $messages = $pseudotron->verify('my_file.xml');
if ($messages) {
    # we got warnings or errors during validation...
    ...
}
OR, in an array context
my @messages = $pseudotron->verify('my_file.xml');

DESCRIPTION

XML::Schematron::XPath serves as a simple validator for
XML based on Rick JELLIFFE's Schematron XSLT script. A
Schematron schema defines a set of rules in the XPath lan
guage that are used to examine the contents of an XML doc
ument tree.

A simplified example:: <schema>
<pattern>
<rule context="page">
<assert test="count(*)=count(title|body)">The page el

ement may only contain title or body elements.</assert>
<assert test="@name">A page element must contain a

name attribute.</assert>
<report test="string-length(@name) < 5">A page ele

ment name attribute must be at least 5 characters long.</report>

</rule>

</pattern>; </schema>
Note that an 'assert' rule will return if the result of the test expression is not true, while a 'report' rule will return only if the test expression evalutes to true.

METHODS

new(): The 'new' constructor accepts the following "named"
arguments:; � schema
The filename of the schema to use for generating
tests.; � tests
The tests argument is an alternative to the use of a schema as a means for defining the test stack.
It should be a reference to a list of lists where
the format of the sub-lists must conform to the
following order:

[$xpath_exp, $context, $message, $test_type,

$pattern]
schema(): When called with a single scalar as its argument, this
method sets/updates the schema file to be used for
generatng tests. Otherwise, it simply returns the name
of the schema file (if any).
tests(): When called with a reference to a list of lists as its
argument (see the format in the description of the
'tests' argument to the new() method for details),
this method sets the current test stack. Otherwise, it
returns an arrayref to the current test stack (if
any).
add_test(%args);: The add_test() method allows you push additional tests on to the stack before validation using the typical
"hash of named parameters" style.; Arguments for this method:; � expr (required)
The XPath expression to evaluate.; � context (required)
An element name or XPath location to use as the
context of the test expression.; � type (required)
The type argument must be set to either 'assert'
or 'report'. Assert tests will return the associ
ated message only if the the corresponding test
expression is not true, while 'report' tests will
return only if their associated test expression
are true.; � message (required)
The text message to display when the test condi
tion is met.; � pattern (optional)
Optional descriptive text for the returned message
that allows a logical grouping of tests.

Example:

$obj->add_test(expr => 'count(@*) > 0',
context => '/pattern',
message => 'Pattern should have

at least one attribute',
type => 'assert',
pattern => 'Basic tests');
Note that add_test() pushes a new test on to the existing test list, while tests() redefines the
entire list.
verify('my_xml_file.xml' or $some_xml_string): The verify() method takes the path to the XML document that you wish to validate, or a scalar containing the
entire document as a string, as its sole argument. It
returns the messages that are returned during valida
tion. When called in an array context, this method
returns an array of the messages generated during val
idation. When called in a scalar context, this method
returns a concatenated string of all output.

CONFORMANCE

XML::Schematron::XPath does not conform to the current Schematron specification since more modern versions allow
XSLT-specific expressions to be used as tests. Please
note, however, that robust validation is still quite pos
sible using just the XPath language.

AUTHOR

Kip Hampton, khampton@totalcinema.com

docs.sk

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