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Description:

plone.uuid 2.0.1

plone.uuid
This is a minimal package that can be used to obtain a universally unique
identifier (UUID) for an object.
The default implementation uses the Python standard library uuid module
to generate an RFC 4122-compliant UUID, using the uuid4() function. It
will assign a UUID upon object creation (by subscribing to
IObjectCreatedEvent from zope.lifecycleevent) and store it in an
attribute on the object.

Why use an attribute and not annotations? The most common form of annotation
is the one provided by IAttributeAnnotations. This stores annotations in
a BTree in an attribute called __annotations__, which means that
annotation values do not end up in the same ZODB persistent object as the
parent. This is good for “large” values, but not very good for small ones
that are frequently required, as it requires a separate ZODB object load.

Simple usage
To automatically assign a UUID to your objects using the default
implementation outlined above, you should:

Make sure they implement plone.uuid.interfaces.IAttributeUUID. You
can do this in code, via the implements() directive, or in ZCML, with
a statement like:
<class class="my.package.MyClass">
<implements interface="plone.uuid.interfaces.IAttributeUUID" />
</class>

Make sure that an IObjectCreatedEvent is fired for this object when it
is first created.

Once the event handler has triggered, you can obtain a UUID by adapting the
object to the IUUID interface:
from plone.uuid.interfaces import IUUID
uuid = IUUID(context)
The uuid variable will now be a (byte) string containing a UUID. If the
UUID has not yet been assigned, adaptation will fail with a TypeError.
If you would rather get None instead of a TypeError, you can do:
uuid = IUUID(context, None)

UUID view
If you require a UUID in a page template or remotely, you can use the
@@uuid view, which is registered for all objects that provide the
IUUIDAware marker interface (which is a super-interface of the
IAttributeUUID marker seen above).
For example:
<div tal:attributes="id string:uuid-${context/@@uuid}">
...
</div>
The view simply returns the UUID string as looked up by the IUUID adapter.

Customising behaviour
There are two primary customisation points for this package:

You can change the default UUID generating algorithm by overriding the
unnamed utility providing the IUUIDGenerator interface. The default
implementation simply calls uuid.uuid4() and casts the result to a
str.
You can change the UUID storage by providing a custom IUUID adapter
implementation. If you do this, you must also provide a mechanism for
assigning UUIDs upon object creation, usually via an event handler. To
obtain a UUID, use the IUUIDGenerator interface:
from zope.component import getUtility
from plone.uuid.interfaces import IUUIDGenerator

generator = getUtility(IUUIDGenerator)
uuid = generator()
You should also make sure that instances with a UUID provide a sub-interface
of plone.uuid.interfaces.IUUIDAware.

Changelog

2.0.1 (2024-01-22)
Internal:

Update configuration files.
[plone devs] (237ff4c8, 6e36bcc4)

2.0.0 (2023-04-26)
Breaking changes:

Drop python 2.7 support.
[gforcada] (#1)

Internal:

Update configuration files.
[plone devs] (2ed8f544)

1.0.6 (2020-04-22)
Bug fixes:

Minor packaging updates. (#1)

1.0.5 (2018-01-18)
Bug fixes:

Fix package dependencies.
[gforcada]
Fix documentation and uuid generator class name to reflect the fact that we use the uuid4 implementation instead of uuid1.
[thet]

1.0.4 (2016-06-02)
Bug fixes:

Update setup.py url to point to github.
[esteele]
Fixed issues preventing tests passing on Python 3
[datakurre]

1.0.3 (2012-05-31)

Use zope.browserpage.
[hannosch]
Defensive UUID assignment in addAttributeUUID() handler: keep existing
UUID value if handler called more than once, except in case of object
copy event, where original and destination should have distinct UUID.
[seanupton]

1.0.2 - 2011-10-18

Generate UUID without dashes.
[elro]

1.0.1 - 2011-05-20

Relicense under modified BSD license.
See http://plone.org/foundation/materials/foundation-resolutions/plone-framework-components-relicensing-policy
[davisagli]

1.0 - 2011-05-13

Release 1.0 Final
[esteele]
Add MANIFEST.in.
[WouterVH]

1.0b2 - 2011-01-03

Add MutableUUID component
[toutpt]

1.0b1 - 2010-11-27

Initial release