Markup Selection in Admin

This method lets you define your markup language and then processes your entries and puts the HTML output in another field on your database. I came from a content management system that worked like this and to me it makes sense. Your system doesn't have to process your entry every time it has to display it. You would just call the "*_html" field in your template. Requires: Django .96 [Markdown](http://cheeseshop.python.org/pypi/Markdown/1.6 "Python Package Index: Markdown") [Textile](http://cheeseshop.python.org/pypi/textile "Python Package Index: Textile")

• admin
• model
• markup
• markdown
• textile

Sun 11 Jul 2010 Read More

Case-insensitive lookup by default

I wanted lookups on tags to be case insensitive by default, so that things like Tag.objects.get(name='Tag') would return any similar tags (ignoring case differences), i.e. `<Tag: tag>`. This snippet makes lookup on the 'name' field case-insensitive by default, although case-sensitive lookups can still be achieved with 'name__exact'. Methods like get_or_create will work as expected and be case-insensitive.

• model
• tags
• tagging
• manager
• case-insensitive
• iexact
• queryset

Sun 11 Jul 2010 Read More

Subclassing a model.field for newforms

The newforms fields are more capable than the django models fields. In this snippet, we subclass models.IntegerField, and add min_value and max_value. e.g. age = MMIntegerField('How old are you?', min_value=13, max_value=120)

• newforms
• fields
• model

Sun 11 Jul 2010 Read More

Using Python properties in models

After reading the comment to my [snippet #49](http://www.djangosnippets.org/snippets/49/) it occurs to me that Python properties may not be obvious to everyone, and may be underutilized in Django models. Here is a simple example demonstrating a property to format a Person's name.

• property
• model

Sun 11 Jul 2010 Read More

Model Mixin to Save Only Changed Fields

**[Improved and Released as Save The Change.](https://github.com/karanlyons/django-save-the-change)** Django 1.5 added the `update_fields` `kwarg` to `Model.save()`, which allows the developer to specify that only certain fields should actually be committed to the database. However, Django provides no way to automatically commit only changed fields if they're not specified. This mixin keeps track of which fields have changed from their value in the database, and automatically applies `update_fields` to update only those fields.

• model
• save
• mixin
• class
• automatic
• update_fields

Wed 06 May 2015 Read More

Gravatar support in model save override

Overridden save() method that adds Gravatar support for a user with a profile photo field (and presumably an email field). Checks to see if user has provided a photo. If not, then query Gravatar for a possible photo. Finally, if Gravatar does not have an appropriate photo for this user, then use whatever default photo is available (in this case, 'users/photos/default_profile_photo.png'... change as necessary).

• model
• save
• override

Wed 03 Apr 2013 Read More

Binding signals to abstract models

Intro ----- I found a question on SO for which Justin Lilly's answer was correct but not as thorough as I'd like, so I ended up working on a simple snippet that shows how to bind signals at runtime, which is nifty when you want to bind signals to an abstract class. Bonus: simple cache invalidation! Question -------- [How do I use Django signals with an abstract model?](http://stackoverflow.com/questions/2692551/how-do-i-use-django-signals-with-an-abstract-model) I have an abstract model that keeps an on-disk cache. When I delete the model, I need it to delete the cache. I want this to happen for every derived model as well. If I connect the signal specifying the abstract model, this does not propagate to the derived models: pre_delete.connect(clear_cache, sender=MyAbstractModel, weak=False) If I try to connect the signal in an init, where I can get the derived class name, it works, but I'm afraid it will attempt to clear the cache as many times as I've initialized a derived model, not just once. Where should I connect the signal? Answer ------ I've created a custom manager that binds a post_save signal to every child of a class, be it abstract or not. This is a one-off, poorly tested code, so beware! It works so far, though. In this example, we allow an abstract model to define CachedModelManager as a manager, which then extends basic caching functionality to the model and its children. It allows you to define a list of volatile keys that should be deleted upon every save (hence the post_save signal) and adds a couple of helper functions to generate cache keys, as well as retrieving, setting and deleting keys. This of course assumes you have a cache backend setup and working properly.

• managers
• models
• cache
• model
• manager
• signals
• abstract
• signal
• contribute_to_class

Thu 25 Apr 2024 Read More

Easier chainability with custom QuerySets

Django allows you to specify your own ModelManager with custom methods. However, these methods are chainable. That is, if you have a method on your PersonManager caled men(), you can't do this: Person.objects.filter(birth_date__year=1978).men() Normally, this isn't a problem, however your app may be written to take advantage of the chainability of querysets. For example, you may have an API method which may return a filtered queryset. You would want to call with_counts() on an already filtered queryset. In order to overcome this, we want to override django's QuerySet class, and then make the Manager use this custom class. The only downside is that your functions will not be implemented on the manager itself, so you'd have to call `Person.objects.all().men()` instead of `Person.objects.men()`. To get around this you must also implement the methods on the Manager, which in turn call the custom QuerySet method.

• model
• manager
• queryset

Wed 30 Jan 2013 Read More

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

Mon 06 Feb 2012 Read More

Password Validation - Require Letters and Numbers - no regex

Simple password validation for user registration - requires that password be 7 or more characters and contain both letters and numbers. Original validation with regex approach developed by kurtis. Optimized no-regex version based on code from watchedman ran as fast or significantly faster on all systems on which we tested it.

• registration
• model
• regex
• user
• validation
• form
• password

Tue 15 Nov 2016 Read More

Better Django Model Field Choices

Nice to name your constant multiple choice fields in models, this is one way of doing that. Sorry I haven't looked into existing alternatives. But this approach worked for me.

• choice
• choices
• model
• field

Sat 05 Mar 2011 Read More

Model merging function

Generic function to merge model instances. Useful when you need to merge duplicate models together, e.g. for users. Based on http://djangosnippets.org/snippets/382/, with several enhancements: * *Type checking*: only Model subclasses can be used and testing that all instances are of same model class * *Handles symmetrical many-to-may*: original snippet failed in that case * *Filling up blank attrs of original when duplicate has it filled* * *Prepared to use outside of command-line*

• django
• model
• generic
• related
• merge

Wed 26 Aug 2015 Read More

Modeli18n

This is a Model base class used to support internationalization (i18n) for your models. This code extends the Django's Model class so you can use all available options from Model safely. Basicly, it uses introspection to create a sub-model to your model to hold translation. **Features:** 1. Simplicity of use. You simply extend your model with this class and add all the fields that needs to be translated are placed under the `locale` sub-class; 2. The code uses the `django.utils.translation.get_language()` to select the current language; 3. You can use `python ./manage.py syncdb` command safely; 4. Force the user to enter a translation for each language even if the fields can be blank. This makes sure that all objects are returned safely. **Ordering by locale fields:** To sort on translated fields, use the form of "model_i18n__transfieldname" (see code for example). **Limitation:** Do not use localized fields in __unicode__, the admin will throw an exception when you'll add a new item and do "save and continue". Just drop a comment if you need more information. (last update: 06/15/2010)

• internationalization
• i18n
• model
• locale
• translation
• culture

Fri 22 Apr 2011 Read More

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

Wed 02 Jan 2013 Read More

another UserForeignKey

This is another foreign key to User model. User is automatically associated before save. Requires: [ThreadlocalsMiddleware](http://code.djangoproject.com/wiki/CookBookThreadlocalsAndUser) Inspired by: [snippet 509](http://www.djangosnippets.org/snippets/509/)

• foreignkey
• model
• user
• field
• users
• user-foreign-key

Wed 24 Feb 2016 Read More