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All snippets written in Python

2959 snippets

Snippet List

Overwriting file storage

Useful if you can make sure your files will never collide unless they share the same contents. You point to the storage parameter when you declare an ImageField and use the hashed_path class method (seemed to make sense to bundle it with the class) to build a custom upload_to method that has to generate the path based on the file contents. Combining both will allow you to deduplicate files uploaded repeatedly.

  • file storage
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Dynamically alter the attributes of a formset

Allow you to specify a "General case formset/modelformset" and then alter the attributes of that formset, specificly: extra, can_order, can_delete and max_num. So you specify: >>> formset = AuthorFormSet(queryset=Author.objects.filter(name__startswith='O')) and then you want to dynamically add multiple fields with javascript and save the new ones. By default a formset only has 1 extra field. With this you can return a new formset (using the same queryset, forms, formset base class, etc) but with different attributes. So you could then add 10 extra fields if the user added 10 new forms.

  • dynamic
  • formset
  • attributes
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Limit queryset to objects related to parent in ManyToMany fields within admin inlines

`formfield_for_manytomany` allows you to limit the choices/queryset for a ManyToManyField, but without direct access to the parent object. This snippet stores a reference to the parent object in `get_formset` and allows limiting of `ManyToManyField`s to objects related to the same parent object. See `ExampleInline` for example usage. If for some reason you have a `ManyToManyField` in a `TabularInline`, just change the `template` in the subclass.

  • limit_choices_to ManyToMany ManyToManyField admin inline formfield_for_manytomany
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Convenient class based views

I needed to use class based views, but I wanted to be able to use the full name of the class in my URLconf without always having to instantiate the view class before using it. What helped me was a surprisingly simple metaclass. I can now both instantiate view classes and use the instances as view functions, OR I can simply point my URLconf to my class and have the metaclass instantiate (and call) the view class for me. This works by checking the first argument to `__call__` – if it's a `HttpRequest`, it must be an actual HTTP request because it would be nonsense to attept to instantiate a view class with an `HttpRequest` instance. The `View` base class contains a overridable before method that can be used to add a common procedure to handlers of different HTTP requests. The `before` method can modify the args and kwargs of the request handlers to be able to replace, say, `model_id` with `model`.

  • views class-based-views classes metaclass
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FieldStack - easy form template rendering

FieldStack simplifies forms template rendering. This is enhanced version of snippet [1786](http://djangosnippets.org/snippets/1786/)

  • template
  • fields
  • forms
  • templates
  • fieldset
  • form
  • object
  • field
  • lazy
  • fieldsets
  • groups
  • stacked
  • descriptor
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Database Routing by URL

An example of how to select the "default" database based on the request URL instead of the model. The basic idea is that the middleware `process_view` (or `process_request`) function sets some context from the URL into thread local storage, and `process_response` deletes it. In between, any database operation will call the router, which checks for this context and returns an appropriate database alias. In this snippet, it's assumed that any view in the system with a `cfg` keyword argument passed to it from the urlconf may be routed to a separate database. Take this urlconf for example: `url( r'^(?P<cfg>\w+)/account/$', 'views.account' )` The middleware and router will select a database whose alias is `<cfg>`, or "default" if none is listed in `settings.DATABASES`, all completely transparent to the view itself.

  • multidb database router url
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csrf_token for mako

Tag that can be used as `${ tags.csrf_token() }` in mako templates. Remember to import the tags namespace in your template, as such: <%namespace name="tags" module="my_app.tags"/>

  • mako csrf_token csrf
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Detect iPhone & Switch Template via render_to_response

A fast way to implement an iPhone template switcher, especially if you have a lot of existing views using the render_to_response() shortcut. This checks for the iPhone browser and then modifies the chosen template by adding -mobile to the html's file name. Check out [this more complete list of user agents](http://minidetector.googlecode.com/svn/trunk/minidetector/tests/mobile_useragents.txt) if you need to detect specific mobile devices.

  • iphone template render_to_response
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Generating aggregate data across generic relations

http://github.com/coleifer/django-generic-aggregation http://charlesleifer.com/blog/generating-aggregate-data-across-generic-relations/ Generate and calculate aggregations across generic foreign keys. >>> from misc import generic_annotate, generic_aggregate >>> from blog.models import Entry >>> from tagging.models import TaggedItem >>> from django.db.models import Count >>> qs = generic_annotate(Entry.objects.all(), TaggedItem.object, 'id', Count) >>> qs[0].score 5L >>> qs[1].score 4L >>> qs[1].tags u'databases django many-to-many python' >>> generic_aggregate(Entry.objects.all(), TaggedItem.object, 'id', Count) 106L # total number of times entries were tagged

  • django
  • gfk
  • aggregation
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Mobile Device Middleware

Middleware class that checks the user agent against a known list of strings found in mobile devices, and if matched it then tries to determine the name of the template being rendered based on the convention of having every view use a keyword arg called "template". It then adds "mobile" to the template name and if the mobile template exists, it will override the "template" arg for the view with the mobile template name.

  • middleware
  • template
  • mobile
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