author | Todd Larsen <tlarsen@google.com> |
Wed, 01 Oct 2008 02:23:30 +0000 | |
changeset 231 | e2782aacfec7 |
parent 110 | e310681d5509 |
child 274 | 56e1c1721299 |
permissions | -rw-r--r-- |
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Base classes for all Datastore Models in Melange.
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#!/usr/bin/python2.5 |
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Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
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# |
e310681d5509
Base classes for all Datastore Models in Melange.
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parents:
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# Copyright 2008 the Melange authors. |
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Base classes for all Datastore Models in Melange.
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# |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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# Licensed under the Apache License, Version 2.0 (the "License"); |
e310681d5509
Base classes for all Datastore Models in Melange.
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# you may not use this file except in compliance with the License. |
e310681d5509
Base classes for all Datastore Models in Melange.
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# You may obtain a copy of the License at |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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# |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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# http://www.apache.org/licenses/LICENSE-2.0 |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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# |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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# Unless required by applicable law or agreed to in writing, software |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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# distributed under the License is distributed on an "AS IS" BASIS, |
e310681d5509
Base classes for all Datastore Models in Melange.
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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# See the License for the specific language governing permissions and |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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# limitations under the License. |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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|
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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"""Module containing enhanced db.Model classes. |
e310681d5509
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Todd Larsen <tlarsen@google.com>
parents:
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|
e310681d5509
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Todd Larsen <tlarsen@google.com>
parents:
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The classes in this module are intended to serve as base classes for all |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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Melange Datastore Models. |
e310681d5509
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Todd Larsen <tlarsen@google.com>
parents:
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""" |
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Todd Larsen <tlarsen@google.com>
parents:
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|
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Todd Larsen <tlarsen@google.com>
parents:
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__authors__ = [ |
e310681d5509
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'"Todd Larsen" <tlarsen@google.com>', |
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Base classes for all Datastore Models in Melange.
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] |
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|
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Todd Larsen <tlarsen@google.com>
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from google.appengine.ext import db |
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|
e310681d5509
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from soc.views.helpers import forms_helpers |
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class ModelWithFieldAttributes(db.Model): |
e310681d5509
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"""A db.Model extension that provides access to Model properties attributes. |
e310681d5509
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|
e310681d5509
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Due to the way the Property class in Google App Engine implements __get__() |
e310681d5509
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Todd Larsen <tlarsen@google.com>
parents:
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and __set__(), it is not possible to access attributes of Model properties, |
e310681d5509
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such as verbose_name, from within a Django template. This class works |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
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around that limitation by creating an inner Form class per Model class, |
e310681d5509
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Todd Larsen <tlarsen@google.com>
parents:
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since an unbound Form object contains (most of?) the property attributes |
e310681d5509
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parents:
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attached to each corresponding Form field. |
e310681d5509
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Todd Larsen <tlarsen@google.com>
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|
e310681d5509
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Some are attributes are renamed during the conversion from a Model Property |
e310681d5509
Base classes for all Datastore Models in Melange.
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parents:
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to a Form field; for example, verbose_name becomes label. This is tolerable |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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because any actual Form code refers to these new names, so they are should |
e310681d5509
Base classes for all Datastore Models in Melange.
Todd Larsen <tlarsen@google.com>
parents:
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be familiar to view creators. |
e310681d5509
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Todd Larsen <tlarsen@google.com>
parents:
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""" |
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Todd Larsen <tlarsen@google.com>
parents:
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_fields_cache = None |
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@classmethod |
e310681d5509
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def fields(cls): |
e310681d5509
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"""Called by the Django template engine during template instantiation. |
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|
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Since the attribute names use the Form fields naming instead of the |
e310681d5509
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Todd Larsen <tlarsen@google.com>
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Property attribute naming, accessing, for example: |
e310681d5509
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{{ entity.property.verbose_name }} |
e310681d5509
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is accomplished using: |
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{{ entity.fields.property.label }} |
e310681d5509
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Args: |
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cls: Model class, so that each Model class can create its own |
e310681d5509
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unbound Form the first time fields() is called by the Django |
e310681d5509
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template engine. |
e310681d5509
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Todd Larsen <tlarsen@google.com>
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Returns: |
e310681d5509
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A (created-on-first-use) unbound Form object that can be used to |
e310681d5509
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access Property attributes that are not accessible from the |
e310681d5509
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Property itself via the Model entity. |
e310681d5509
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Todd Larsen <tlarsen@google.com>
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""" |
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if not cls._fields_cache or (cls != cls._fields_cache.__class__.Meta.model): |
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class FieldsProxy(forms_helpers.DbModelForm): |
e310681d5509
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"""Form used as a proxy to access User model properties attributes. |
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""" |
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class Meta: |
e310681d5509
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"""Inner Meta class that pairs the User Model with this "form". |
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""" |
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#: db.Model subclass for which to access model properties attributes |
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model = cls |
e310681d5509
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cls._fields_cache = FieldsProxy() |
e310681d5509
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Todd Larsen <tlarsen@google.com>
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|
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return cls._fields_cache |