HibernateBooleanField
Sometimes its necessary to map your django models to Java Hibernate created tables. Hibernate maps boolean field to bit(1) column instead of tinyint in django. NOTE: tested for mysql backend only
- model
- field
- hibername
Snippet List
JsonObjectField
This fields.py file defines a new model field type, "JsonObjectField," which is designed to allow the storage of arbitrary Python objects in Django TextFields. It is intended primarily to allow the storage of Python dictionaries or list objects. As the name implies, it converts objects to JSON for storage; this conversion happens transparently, so from your model's perspective, the field stores and retrieves the actual objects.
- model
- json
- database
- object
ParentModel and ChildManager for Model Inheritance
This is the approach I've taken to access instances of child models from their parent. Functionally it's very similar to snippets [1031](http://www.djangosnippets.org/snippets/1031/) and [1034](http://www.djangosnippets.org/snippets/1034/), but without the use of `django.contrib.contenttypes`. Usage: class Post(ParentModel): title = models.CharField(max_length=50) objects = models.Manager() children = ChildManager() def __unicode__(self): return self.title def get_parent_model(self): return Post class Article(Post): text = models.TextField() class Photo(Post): image = models.ImageField(upload_to='photos/') class Link(Post): url = models.URLField() In this case, the `Post.children` manager will return a queryset containing instances of the appropriate child model, rather than instances of `Post`. >>> Post.objects.all() [<Post: Django>, <Post: Make a Tumblelog>, <Post: Self Portrait>] >>> Post.children.all() [<Link: Django>, <Article: Make a Tumblelog>, <Photo: Self Portrait>]
- model
- manager
- queryset
- inheritance
True Unique Boolean Model Decorator
This class decorator will help you when you want to keep a unique boolean (think a 'default' field which should only be only one set to true in a group). The interesting thing with this, is that it's possible to assign a subset of fields to be used, so that the uniqueness of the field will be guaranteed among only the subset (look at the Example section in the code to understand this behaviour). This is a better and improved way of doing http://djangosnippets.org/snippets/2676/
- model
- unique
- boolean
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
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
Phone Model
This is standart phone model.
- model
- phone
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
Allow filtering and ordering by counts of related query results
I know you're thinking, *what the heck could that title mean?* I often find myself wanting to filter and order by the result of a COUNT(*) of a query using a method similar to the [entry_count example](http://www.djangoproject.com/documentation/db-api/#extra-select-none-where-none-params-none-tables-none). Writing this many times is tedious and hardcoding the table and column names made me cringe, I also wanted the counts to result from more complex queries. This is a method you can add to your custom Manager to do this easily. It's not an ideal syntax, but it's good for the amount of code required. Example: suppose we have some articles we want to filter and order by comments and visit logs to show the most popular... class ArticleManager(models.Manager): count_related = _count_related class Article(models.Model): pub_date = models.DateTimeField(auto_now_add=True) objects = ArticleManager() class Comment(models.Model): article = models.ForeignKey(Article) is_spam = models.BooleanField(default=False) class Visit(models.Model): article = models.ForeignKey(Article) referrer = models.URLField(verify_exists=False) search_query = models.CharField(maxlength=200) Notice how the ArticleManager is given the `count_related` method. Now you can find the most popular like so... Order by non-spam comments: Article.objects.count_related(Comment.objects.filter( is_spam=False)).order_by('-comment__count') Order by incoming non-search-engine links: Article.objects.count_related(Visit.objects.filter( referrer__isnull=False, search_query__isnull=True), 'links').order_by('-links') Order by total visits: Article.objects.count_related(Visit).order_by('-visit__count') Note: Doesn't work if `query` contains joins or for many-to-many relationships, but those could be made to work identically if there's demand.
- sql
- model
- db
- count
- manager
True Unique Boolean Decorator
Useful when you want to keep only one instance of a model to be the default one. This is a decorative way of doing the same as in http://djangosnippets.org/snippets/1830/ Can this be made better as a class decorator (not having to declare explicitly the save method) ?
- model
- unique
- boolean
Model Locking Mixin & Decorator (MySQL Advisory Locks)
This code provides a mixin and decorator which, when used together, can provide advisory locking on model methods. It provides locking by using MySQL's advisory lock system. See the example at the bottom of the code. This is a convenient and easy way to guarantee your model methods have exclusive access to a model instance. The LockableObjects class requires a MySQL backend, but it could be modified to use other back-end locking systems. The lock name generation in `LockableObject.get_lock_name()` could be altered to create much more complex locking schemes. Locking per-object, per-method for example.. Lock attempts have a timeout value of 45 seconds by default. If a timeout occurs, EnvironmentError is raised. **See the bottom of the script for an example** > **Instructions:** * **1:** Place the code in locking.py somewhere in your path * **2:** In your models.py (or any script with an object you want to lock): `from locking import LockableObject, require_object_lock` * **3:** In the model you want locking for, add the `LockableObject` mixin * **4:** Decorate the method you want to be exclusively locked with `@require_object_lock`
- model
- mysql
- decorator
- mixin
- locking
Validating Model subclass
If you inherit from ValidatedModel instead of from models.Model, then full_clean() will be called before save(). So, add validators to your field definitions, and all your fields will be validated before they go to the database. The same thing can be accomplished with a pre_save signal, but the code is quite a bit messier than the simple inheritance above.
- model
- validation
- subclass
More readable Enumeration class for Django choices
We currently use two-level tuples to specify choices of a field in models or forms. But, because it has only (value, verbose name) pair, the readability is bad whenever we indicate a specific choice value in our Python codes. So I made a small class that does "magic" for this: A Named Enumeration. Instead of `myobj.status == 0`, use `myobj.status == STATUS.UNREVIEWED`, for example.
- choices
- model
- orm
- enumeration
- enum
update_or_create
Django provides a `get_or_create` helper method in the `models.Manager` class which looks up an object for the given `kwargs`, creating one if necessary. But sometime you need a method which updates the object with given `kwargs` or creates it if it's not found. This snippet provides the helper for that purpose. Use the snippet like this: from django.db import models class PersonManager(models.Manager): update_or_create = _update_or_create class Person(models.Model): first_name = models.CharField() last_name = models.CharField() city = models.CharField() objects = PersonManager() person, created, updated = Person.objects.update_or_create(first_name="John", last_name="Smith", defaults=dict(city="London")) The method returns a tuple of (`object`, `created`, `updated`), where `created` and `updated` are booleans specifying whether an `object` was created or updated respectively. Both `created` and `updated` are `false` if `object` is neither created nor updated (that is `object` has just been fetched "as is" from db). This happens if the update fails.
- model
- helper
- update
- create
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