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Tag "model"

137 snippets

Snippet List

Django-admin autoregister -- automatic model registration

Automatically register models for the Django-admin. This snippet aids in the process of keeping your admin.py up-to-date with the models in your apps, have all models automatically added to the admin and reflect any future changes without updating the file. [zweckdev.com](http://zweckdev.com/)

  • django
  • models
  • admin
  • model
  • django-admin
  • autoregister
  • auto-register
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Improved Pickled Object Field

[Based on snippet #513 by obeattie.](http://www.djangosnippets.org/snippets/513/) **Update 10/10/09:** [Further development is now occurring on GitHub, thanks to Shrubbery Software.](http://github.com/shrubberysoft/django-picklefield) Incredibly useful for storing just about anything in the database (provided it is Pickle-able, of course) when there isn't a 'proper' field for the job. `PickledObjectField` is database-agnostic, and should work with any database backend you can throw at it. You can pass in any Python object and it will automagically be converted behind the scenes. You never have to manually pickle or unpickle anything. Also works fine when querying; supports `exact`, `in`, and `isnull` lookups. It should be noted, however, that calling `QuerySet.values()` will only return the encoded data, not the original Python object. *Please note that this is supposed to be two files, one fields.py and one tests.py (if you don't care about the unit tests, just use fields.py).* This PickledObjectField has a few improvements over the one in [snippet #513](http://www.djangosnippets.org/snippets/513/). 1. This one solves the `DjangoUnicodeDecodeError` problem when saving an object containing non-ASCII data by base64 encoding the pickled output stream. This ensures that all stored data is ASCII, eliminating the problem. 2. `PickledObjectField` will now optionally use `zlib` to compress (and uncompress) pickled objects on the fly. This can be set per-field using the keyword argument "compress=True". For most items this is probably **not** worth the small performance penalty, but for Models with larger objects, it can be a real space saver. 3. You can also now specify the pickle protocol per-field, using the protocol keyword argument. The default of `2` should always work, unless you are trying to access the data from outside of the Django ORM. 4. Worked around a rare issue when using the `cPickle` and performing lookups of complex data types. In short, `cPickle` would sometimes output different streams for the same object depending on how it was referenced. This of course could cause lookups for complex objects to fail, even when a matching object exists. See the docstrings and tests for more information. 5. You can now use the `isnull` lookup and have it function as expected. A consequence of this is that by default, `PickledObjectField` has `null=True` set (you can of course pass `null=False` if you want to change that). If `null=False` is set (the default for fields), then you wouldn't be able to store a Python `None` value, since `None` values aren't pickled or encoded (this in turn is what makes the `isnull` lookup possible). 6. You can now pass in an object as the default argument for the field without it being converted to a unicode string first. If you pass in a callable though, the field will still call it. It will *not* try to pickle and encode it. 7. You can manually import `dbsafe_encode` and `dbsafe_decode` from fields.py if you want to encode and decode objects yourself. This is mostly useful for decoding values returned from calling `QuerySet.values()`, which are still encoded strings. The tests have been updated to match the added features, but if you find any bugs, please post them in the comments. My goal is to make this an error-proof implementation. **Note:** If you are trying to store other django models in the `PickledObjectField`, please see the comments for a discussion on the problems associated with doing that. The easy solution is to put django models into a list or tuple before assigning them to the `PickledObjectField`. **Update 9/2/09:** Fixed the `value_to_string` method so that serialization should now work as expected. Also added `deepcopy` back into `dbsafe_encode`, fixing #4 above, since `deepcopy` had somehow managed to remove itself. This means that lookups should once again work as expected in **all** situations. Also made the field `editable=False` by default (which I swear I already did once before!) since it is never a good idea to have a `PickledObjectField` be user editable.

  • model
  • db
  • orm
  • database
  • pickle
  • object
  • field
  • type
  • pickled
  • store
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JSONField

This is a custom field that lets you easily store JSON data in one of your model fields. This is updated to work with Django 1.1. **Example: (models.py)** from django.db import models import JSONField class MyModel(models.Model): info = JSONField() ** Example: (shell)** >>> obj = MyModel.objects.all()[0] >>> type(obj.info) <type 'NoneType'> >>> obj.info = {"test": [1, 2, 3]} >>> obj.save() **[Code at GitHub](http://github.com/bradjasper/django-jsonfield/tree/master)**

  • models
  • fields
  • model
  • json
  • db
  • field
  • json-field
  • jsonfield
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MAC address field

Supported MAC formats: aa:bb:cc:dd:ee:ff, separator : or - aabbccddeeff both lower case and upper case

  • model
  • field
  • custom-field
  • address
  • mac
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MarkupTextField

I updated [MarkdownTextField](http://www.djangosnippets.org/snippets/882/) to have some choices in markup. It currently support for Markdown, Textile, Plain Text, and Plain HTML. It will add `%s_html` for the complied HTML and `%s_markup_choices` for a drop down of markup choices. Usage: class MyModel(models.Model): description = MarkupTextField()

  • model
  • markup
  • markdown
  • textile
  • field
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keeping Model and Field History (everywhere)

Usage: class MyModel(ModelWithHistory): class History: model = True # save model changes into admin's LogEntry table fields = ('f1', 'f2') # save these fields history to AttributeLogEntry table f1 = CharField(max_length=100) f2 = IntegerField() for threadlocals, see http://code.djangoproject.com/wiki/CookBookThreadlocalsAndUser Aware! Not thoroughly tested yet. May cause problems with loading fixtures.

  • model
  • history
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local django model test

Sometimes you need to test some model features without a complete django app installation. Just play only with the model object. With these small script you have a complete in memory django installation. Some Links: http://www.djangosnippets.org/snippets/1044/ (en) http://www.jensdiemer.de/permalink/150/mein-blog/99/django-db-model-test/ (de) http://www.python-forum.de/viewtopic.php?f=3&t=15649 (de) See also: https://github.com/readevalprint/mini-django/

  • model
  • testing
  • test
  • local-test
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Copy a model instance

Create a copy of a model instance. Works in model inheritance case where ``instance.pk = None`` is not good enough, since the subclass instance refers to the parent_link's primary key during save. M2M relationships are currently not handled, i.e. they are not copied. See also Django #4027.

  • model
  • copy
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PositionField

**This is a model field for managing user-specified positions.** Usage ===== Add a `PositionField` to your model; that's just about it. If you want to work with all instances of the model as a single collection, there's nothing else required. In order to create collections based on another field in the model (a `ForeignKey`, for example), set `unique_for_field` to the name of the field. It's probably also a good idea to wrap the `save` method of your model in a transaction since it will trigger another query to reorder the other members of the collection. Here's a simple example: from django.db import models, transaction from positions.fields import PositionField class List(models.Model): name = models.CharField(max_length=50) class Item(models.Model): list = models.ForeignKey(List, db_index=True) name = models.CharField(max_length=50) position = PositionField(unique_for_field='list') # not required, but probably a good idea save = transaction.commit_on_success(models.Model.save) Indices ------- In general, the value assigned to a `PositionField` will be handled like a list index, to include negative values. Setting the position to `-2` will cause the item to be moved to the second position from the end of the collection -- unless, of course, the collection has fewer than two elements. Behavior varies from standard list indices when values greater than or less than the maximum or minimum positions are used. In those cases, the value is handled as being the same as the maximum or minimum position, respectively. `None` is also a special case that will cause an item to be moved to the last position in its collection. Limitations =========== * Unique constraints can't be applied to `PositionField` because they break the ability to update other items in a collection all at once. This one was a bit painful, because setting the constraint is probably the right thing to do from a database consistency perspective, but the overhead in additional queries was too much to bear. * After a position has been updated, other members of the collection are updated using a single SQL `UPDATE` statement, this means the `save` method of the other instances won't be called. More === More information, including an example app and tests, is available on [Google Code](http://code.google.com/p/django-positions/).

  • lists
  • models
  • fields
  • model
  • field
  • list
  • sorting
  • ordering
  • collection
  • collections
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ActiveManager: filter objects depending on publication and/or expiration dates

This manager is intended for use with models with publication and/or expiration dates. Objects will be retrieved only if their publication and/or expiration dates are within the current date. Use is very simple: class ExampleModel(models.Model): publish_date = models.DateTimeField() expire_date = models.DateTimeField(blank=True, null=True) objects = models.Manager() actives = ActiveManager(from_date='publish_date', to_date='expire_date') ExampleModel.actives.all() # retrieve active objects according to the current date The manager works correctly with nullable date fields. A null publication date means "*always published (until expiration date)*" and a null expiration date means "*never expires*". Most models should define the `objects` manager as the default manager, because otherwise out of date objects won't appear in the admin app.

  • model
  • manager
  • active
  • publication
  • expiration
  • date-filter
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Manager for something like __inall

Provides the method from_related_ids, which lets you select some objects by providing a list of related ids (The huge difference to __in is that the objects have to match al of the ids, not only one) Model Example:: class Article(models.Model): text = models.TextField() tags = ManyToManyField('Tag') objects = AllInManager() Usage:: Article.objects.from_related_ids((1,2,3,4), 'tags')

  • model
  • db
  • manager
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duplicate model object merging script

Use this function to merge model objects (i.e. Users, Organizations, Polls, Etc.) and migrate all of the related fields from the alias objects the primary object. Usage: from django.contrib.auth.models import User primary_user = User.objects.get(email='[email protected]') duplicate_user = User.objects.get(email='[email protected]') merge_model_objects(primary_user, duplicate_user)

  • django
  • fields
  • model
  • generic
  • related
  • merge
  • duplicates
  • genericforeignkey
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