grokcore.annotation 3.2

Setting up grokcore.annotation

This package is essentially set up like the grokcore.component package, please refer to its documentation for details. The only additional ZCML line you will need is:

<include package="grokcore.annotation" />

Put this somewhere near the top of your root ZCML file but below the line where you include grokcore.component’s configuration.

Example

Here a simple example of use of an annotation:

import grokcore.annotation
from zope import interface

# Create a model and an interface you want to adapt it to
# and an annotation class to implement the persistent adapter.
class Mammoth(grokcore.annotation.Model):
    pass

class ISerialBrand(interface.Interface):
    unique = interface.Attribute("Brands")

class Branding(grokcore.annotation.Annotation):
    grokcore.annotation.implements(ISerialBrand)
    unique = 0

# Grok the above code, then create some mammoths
manfred = Mammoth()
mumbles = Mammoth()

# creating Annotations work just like Adapters
livestock1 = ISerialBrand(manfred)
livestock2 = ISerialBrand(mumbles)

# except you can store data in them, this data will transparently persist
# in the database for as long as the object exists
livestock1.unique = 101
livestock2.unique = 102

# attributes not listed in the interface will also be persisted
# on the annotation
livestock2.foo = "something"

API Overview

Base classes

Annotation

Base class for an Annotation. Inherits from the persistent.Persistent class.

Model

Base class for a Model on which you want to use an annotation.

queryAnnotation(model, interface)

Query the annotation on the given model for the given interface. Return the annotation if found, None otherwise. This will not make any write operation.

deleteAnnotation(model, interface)

Look for the given annotation and delete it from the model.

LazyAnnotation

Base class for an annotation. It only writes a database object when explicitly setting values on the lazy properties.

LazyAnnotationProperty

Property implementation that works with LazyAnnotation.

In addition, the grokcore.annotation package exposes the grokcore.component API.

Changes