Value - base class for value types for the Oryx object persistence tool
# constructor - this is what you should do
tie $obj->{some_field}, 'Oryx::Value::SomeType', ($meta, $owner);
# this is if you really must call these methods on the tied object
# although normally these are called by the tied object on $self
tied($obj->{some_field})->deflate($value);
tied($obj->{some_field})->inflate($value);
tied($obj->{some_field})->check($value);
tied($obj->{some_field})->check_required($value);
tied($obj->{some_field})->check_type($value);
tied($obj->{some_field})->check_size($value);
tied($obj->{some_field})->meta;
tied($obj->{some_field})->owner;
This module is considered abstract and should be sublcassed to create the actual
Value types.
The purpose of these Value types is to validate input and to
prepare field values for storage in the database via the
"deflate" method and to prepare the values
for consumption after retrieval via the
"inflate" method.
The tie constructor is passed the associated Oryx::Attribute
instance which can be accessed via "meta",
along with the Oryx::Class instance to which the Attribute - and therefore
the value - belongs. The Oryx::Class instance can be accessed with the
"owner" accessor.
The "tie" related methods:
"TIESCALAR",
"STORE" and
"FETCH", as well as
"VALUE" should not be overridden when
subclassing - they are documented here for the sake of completeness.
The "inflate",
"deflate",
"check_thing", and
"primitive" methods are usually overloaded
when subclassing.
- TIESCALAR( $meta, $owner )
- takes two arguments: $meta and
$owner - $meta is the
Oryx::Attribute instance with which this value is associated, and
$owner is the Oryx::Class instance (or persistent
object).
This method should not be called directly, instead use
my $attr_name = $attrib->name;
tie $object->{$attr_name}, 'Oryx::Value::String', $attrib, $object;
- FETCH
- automatically called by Perl when the field to which this Value is tied is
retrieved. You should not normally need to call this directly.
- STORE( $value )
- automatically called by Perl when the field to which this Value is tied is
set via assignment. You should not normally need to call this
directly.
- VALUE
- mutator to the internal raw value held in this tied object instance
- deflate( $value )
- hook to modify the value before it is stored in the db.
$value is the raw value associated with the
attribute as it is in the live object. This is not neccessarily the same
as its representation in the database. Take Oryx::Value::Complex for
example. Complex serializes its value using YAML before it saves it to the
database. "deflate" does the
serialization in this case. It is passed the value in the live object
which could be a hash ref or array ref (or anything else that could be
serialized using YAML) and returns the serialized YAML string
representation of that value.
- inflate( $value )
- hook to modify the value as it is loaded from the db. This is the
complement to "deflate" in that it takes
the value loaded from the database and cooks it before it is associated
with the attribute of the live
"Oryx::Class" object.
In the case of Oryx::Value::Complex
$value is a YAML string which is deserialized
using YAML and the result returned.
- check( $value )
- hook for checking the value before it is set. You should consider
carefully if you need to override this method as this one calls the other
"check_thing" methods and sets
"$self->errstr" if any of them
fail.
- check_type( $value )
- hook for doing type checking on the passed $value.
Should return 1 if successful and 0 if not.
- check_size( $value )
- hook for doing size checking on the passed $value.
Should return 1 if successful and 0 if not.
- check_required( $value )
- hook for checking if the passed $value is
required. Should return 1 if the value is required and defined and 0 if
required and not defined. If the value is not required, return 1.
- errstr
- returns the error string if input checks failed.
- meta
- simple accessor to meta data for this value type, in this case, a
reference to the Oryx::Attribute with which this Value instance is
associated.
- owner
- returns the Oryx::Class which owns the Oryx::Attribute instance with which
this Value instance is associated.
- primitive
- Returns a string representing the underlying primitive type. This is used
by the storage driver to determine how to pick the data type to use to
store the value. The possible values include:
- Integer
- String
- Text
- Binary
- Float
- Boolean
- DateTime
There is an additional internal type called "Oid", but
it should not be used.
Copyright (C) 2005 Richard Hundt <richard NO SPAM AT protea-systems.com>
This library is free software and may be used under the same terms as Perl
itself.