64 lines
2.5 KiB
ReStructuredText
64 lines
2.5 KiB
ReStructuredText
**2010-1-26**
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IMPORTANT - database schema change (more info in change log).
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I hope I got this change in early enough before anyone started to use
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polymorphic.py in earnest. Sorry for any inconvenience.
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This should be the final DB schema now.
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Usage, Examples, Installation & Documentation, Links
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----------------------------------------------------
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* Please see the `Documentation and Examples`_ (or the short `Overview`_)
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* News & comments: `News, Comments, Questions & Discussion`_
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* The code can be found on GitHub_ and Bitbucket_, or downloaded as TGZ_ or ZIP_
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.. _Documentation and Examples: http://bserve.webhop.org/wiki/django_polymorphic/doc
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.. _News, Comments, Questions & Discussion: http://groups.google.de/group/django-polymorphic/topics
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.. _GitHub: http://github.com/bconstantin/django_polymorphic
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.. _Bitbucket: http://bitbucket.org/bconstantin/django_polymorphic
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.. _TGZ: http://github.com/bconstantin/django_polymorphic/tarball/master
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.. _ZIP: http://github.com/bconstantin/django_polymorphic/zipball/master
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.. _Overview: http://bserve.webhop.org/wiki/django_polymorphic
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What is django_polymorphic good for?
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------------------------------------
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It causes objects being retrieved from the database to always be returned back
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with the same type/class and fields they were created and saved with.
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Example:
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If the models ``ArtProject`` and ``ResearchProject`` inherit from the model ``Project``,
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and we have saved one of each of them into the database, then we can do::
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>>> Project.objects.all()
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.
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[ <Project: id 1, topic: "John's Gathering">,
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<ArtProject: id 2, topic: "Sculpting with Tim", artist: "T. Turner">,
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<ResearchProject: id 3, topic: "Swallow Aerodynamics", supervisor: "Dr. Winter"> ]
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It doesn't matter how these objects are retrieved: be it through the
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model's own managers/querysets, ForeignKeys, ManyToManyFields
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or OneToOneFields.
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``django_polymorphic`` does this only for models that explicitly request
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this behaviour (and implicitely for their submodels).
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The resulting querysets are polymorphic, i.e they may deliver
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objects of several different types in a single query result.
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Status
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------
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It's important to consider that this code is still very new and
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experimental. Please see the docs for current restrictions, caveats,
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and performance implications.
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It does seem to work well for a number of people (including me), but
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it's still very early and API changes, code reorganisations or further
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schema changes are still a possibility.
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Right now it's suitable only for the more enterprising early adopters.
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