django-picklefield 0.2.1

**django-picklefield** provides an implementation of a pickled object field.<br />Such fields can contain any picklable objects.<br /><br />The implementation is taken and adopted from `Django snippet #1694<br />`_ by Taavi Taijala, which is in<br />turn based on `Django snippet #513 `_<br />by Oliver Beattie.<br /><br />django-picklefield is available under the MIT license.<br />First of all, you need to have **django-picklefield** installed; for your<br />convenience, recent versions should be available from PyPI.<br /><br />To use, just define a field in your model::<br /><br /> >>> from picklefield.fields import PickledObjectField<br /> ... class SomeObject(models.Model):<br /> ... args = PickledObjectField()<br /><br />and assign whatever you like (as long as it's picklable) to the field::<br /><br /> >>> obj = SomeObject()<br /> >>> obj.args = ['fancy', {'objects': 'inside'}]<br /> >>> obj.save()<br /><br />If you need to serialize an object with a PickledObjectField for transmission<br />to the browser, you may need to subclass the field and override the<br />``value_to_string()`` method. Currently pickle fields are serialized as<br />base64-encoded pickles, which allows reliable deserialization, but such a<br />format is not convenient for parsing in the browser. By overriding<br />``value_to_string()`` you can choose a more convenient serialization format.<br /><br />Here are the notes by taavi223, the original author:<br /><br />Incredibly useful for storing just about anything in the database (provided it<br />is Pickle-able, of course) when there isn't a 'proper' field for the job.<br /><br />PickledObjectField is database-agnostic, and should work with any database<br />backend you can throw at it. You can pass in any Python object and it will<br />automagically be converted behind the scenes. You never have to manually pickle<br />or unpickle anything. Also works fine when querying; supports exact, in, and<br />isnull lookups. It should be noted, however, that calling QuerySet.values()<br />will only return the encoded data, not the original Python object.<br /><br />This PickledObjectField has a few improvements over the one in snippet #513.<br /><br />This one solves the DjangoUnicodeDecodeError problem when saving an object<br />containing non-ASCII data by base64 encoding the pickled output stream. This<br />ensures that all stored data is ASCII, eliminating the problem.<br /><br />PickledObjectField will now optionally use zlib to compress (and uncompress)<br />pickled objects on the fly. This can be set per-field using the keyword<br />argument "compress=True". For most items this is probably not worth the small<br />performance penalty, but for Models with larger objects, it can be a real space<br />saver.<br /><br />You can also now specify the pickle protocol per-field, using the protocol<br />keyword argument. The default of 2 should always work, unless you are trying to<br />access the data from outside of the Django ORM.<br /><br />Worked around a rare issue when using the cPickle and performing lookups of<br />complex data types. In short, cPickle would sometimes output different streams<br />for the same object depending on how it was referenced. This of course could<br />cause lookups for complex objects to fail, even when a matching object exists.<br />See the docstrings and tests for more information.<br /><br />You can now use the isnull lookup and have it function as expected. A<br />consequence of this is that by default, PickledObjectField has null=True set<br />(you can of course pass null=False if you want to change that). If null=False<br />is set (the default for fields), then you wouldn't be able to store a Python<br />None value, since None values aren't pickled or encoded (this in turn is what<br />makes the isnull lookup possible).<br /><br />You can now pass in an object as the default argument for the field without it<br />being converted to a unicode string first. If you pass in a callable though,<br />the field will still call it. It will not try to pickle and encode it.<br /><br />You can manually import dbsafe_encode and dbsafe_decode from fields.py if you<br />want to encode and decode objects yourself. This is mostly useful for decoding<br />values returned from calling QuerySet.values(), which are still encoded<br />strings.<br /><br />Note: If you are trying to store other django models in the PickledObjectField,<br />please see the comments for a discussion on the problems associated with doing<br />that. The easy solution is to put django models into a list or tuple before<br />assigning them to the PickledObjectField.<br /><br />Update 9/2/09: Fixed the value_to_string method so that serialization should<br />now work as expected. Also added deepcopy back into dbsafe_encode, fixing #4<br />above, since deepcopy had somehow managed to remove itself. This means that<br />lookups should once again work as expected in all situations. Also made the<br />field editable=False by default (which I swear I already did once before!)<br />since it is never a good idea to have a PickledObjectField be user editable.<br /><br />-------<br />Changes<br />-------<br /><br />Changes in version 0.1.5<br />========================<br /><br /> * Added support for South.<br /> * Changed default to null=False, as is common throughout Django.<br /><br />Changes in version 0.1.4<br />========================<br /><br /> * Updated copyright statements.<br /><br />Changes in version 0.1.3<br />========================<br /><br /> * Updated serialization tests (thanks to Michael Fladischer).<br /><br />Changes in version 0.1.2<br />========================<br /><br /> * Added Simplified BSD licence.<br /><br />Changes in version 0.1.1<br />========================<br /><br /> * Added test for serialization.<br /> * Added note about JSON serialization for browser.<br /> * Added support for different pickle protocol versions (thanks to Michael<br /> Fladischer).<br /><br />Changes in version 0.1<br />======================<br /><br /> * First public release.<br /><br /><br />--------<br />Feedback<br />--------<br /><br />There is a `home page `_<br />with instructions on how to access the code repository.

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Platforms:	*nix, Linux
Keyword:	Added,  Browser,  Default,  Expected,  Field,  Fields,  Gtgtgt,  Lookups,  Object,  Objects,  Pickle,  Pickled,  Pickledobjectfield,  Serialization,  Snippet,  Version
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