PPM::XML::ValidatingElement - XML Element with DTD-like validation rules
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PPM::XML::ValidatingElement - XML Element with DTD-like validation rules
use PPM::XML::ValidatingElement;
package PPM::XML::MyElement;
@ISA = qw( PPM::XML::ValidatingElement );
@oattrs = qw( BAR ); # Allow for both FOO and BAR attributes
@rattrs = qw( FOO );
@okids = qw( BLEARGH ); # Allow for both BLEARGH and FOOBAR children
@rkids = qw( FOOBAR );
PPM::XML::ValidatingElement inherits from PPM::XML::Element. It extends
this class to support methods for validation to allow for DTD-like
restrictions to be places on documents read in with the XML::Parser module.
In order to set up rules for validation of elements, each element should
define four list values in it's own package namespace. When validating, this
module will check to ensure that any parsed attributes or child elements are
actually ones that are possible for this element, as well as checking to see
that any required attributes/child elements are present.
Note that an attribute/child element only has to be present in either the
optional or required list; when checking for possible attributes/children,
these lists will be combined.
Validation lists:
- @oattrs
-
List of optional attributes.
- @rattrs
-
List of required attributes.
- @opkids
-
List of optional child elements.
- @rkids
-
List of required child elements.
- validate( err_handler )
-
Validates the current element. This method calls four other methods to
validate all of requirements for the element. Returns non-zero on success and
zero if any errors occurred.
- rvalidate( err_handler )
-
Validates the current element, and recursively validates all child elements.
This method calls four other methods to validate all of the requirements for
the element. Returns non-zero on success and zero if any errors occurred.
- validate_possible_attrs( err_handler )
-
Checks against the list of attributes possible for this element (taken from
@oattr and @rattr) to ensure that all of the parsed attributes are valid. If
any parsed attributes are not in the list of possible attributes for this
element, err_handler will be called with a message stating the error. Returns
non-zero on success and zero if any errors occurred.
- validate_required_attrs( err_handler )
-
Checks against the list of required attributes (taken from @rattr) to ensure
that all of the required attributes are present and have been parsed. If any
required attributes are missing, err_handler will be called with a message
stating the error. Returns non-zero on success and zero if any errors
occurred.
- validate_possible_kids( err_handler )
-
Checks against the list of child elements this element can contain (taken from
@okids and @rkids) to ensure that any child elements that have been read in are
valid. If any child elements have been parsed which are not in the list of
possible children, err_handler will be called with a message stating the
error. Returns non-zero on success and zero if any errors occurred.
- validate_required_kids( err_handler )
-
Checks against the lsit of required child elements (taken from @rkids) to
ensure that all of the required child elements are present and have been
parsed. If any of the required child elements are missing, err_handler will be
called with a message stating the error. Returns non-zero on success and zero
if any errors occurred.
The PPM::XML::ValidatingElement module only provides checks for determining
whether or not the possible/required attributes/children are present. This
module currently has no support for determining whether or not the values
provided are actually valid (although I imagine it wouldn't be too hard to
add this in somewhere). This also includes elements which have been declared
in a DTD as being 'EMPTY' elements.
Graham TerMarsch <grahamt@activestate.com>
v0.2 - Added failure return values to each of the methods.
v0.1 - Initial version
the PPM::XML::Element manpage,
the XML::Parser manpage
PPM::XML::ValidatingElement - XML Element with DTD-like validation rules
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