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All snippets written in Python

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Deep json serialization

Custom serialization, the poor try to make something like [django full serializers](http://code.google.com/p/wadofstuff/wiki/DjangoFullSerializers) Usage: you need two files, goodjson.py and goodpython.py, for example, in the root of application named "core". Then, add two lines into your settings.py: SERIALIZATION_MODULES = {'goodjson' : 'core.goodjson', 'goodpython': 'core.goodpython'} This thing does only serialization, not deserialization. You were warned.

  • serialize
  • json
  • serialization
  • deep
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Ensure ugettext is available absolutely everywhere

Put this into the __init.py__ file in the root of your project (the same directory level as urls.py and settings.py) and this installs _() as a global reference into the current running python VM, and now it’s as universally available as int(), map(), or str(). This is, of course, controversial. Modifying the python global namespace to add a function can be considered maintenance-hostile. But the gettext feature is so universal– at least to me– that __init__.py is where it belongs.

  • internationalization
  • gettext
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Ensure submitted slugs do not conflict with existing resolvable URLs

This code overrides the existing RegistrationForm in django-registration and adds a new validation step. In this step, the username (my example slug) is compared against all the existing URLs that the application currently resolves and, if it *does* successfully resolve, throws a validation exception. This indicates that the username chosen would be overriden (or, if you wrote your urls.py file badly, would override) an existing URL already recognized by your application. A much longer explanation can be found at [Dynamic names as first-level URL path objects in Django](http://www.elfsternberg.com/2009/06/26/dynamic-names-as-first-level-url-path-objects-in-django/).

  • registration
  • slug
  • reverse
  • resolve
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Template-Filter for Feedparser-Dates

A filter that changes a preparsed date from [Ultimate Feedparser](http://www.feedparser.org/) to a regular datetime instance. Now you can -for example- pass a feed parsed by feedparser to a template and do this: {% for item in feed.entries %} Title: {{ item.title }}<br /> Date: {{ item.updated_parsed|feedparsed|date:"Y-m-d" }} {% endfor %}

  • template-filter
  • datetime
  • date
  • feedparser
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Templatetag for granular permissions

If you're using [Django granular permissions](http://code.google.com/p/django-granular-permissions/), this templatetag may be useful. It enables you to check permission in templates, as mentioned in the code: {% has_row_perm user object "staff" as some_var %} {% if some_var %} ... {% endif %} To be used in `if` statements, it always saves the result to the indicated context variable. Put the snippet in row_perms.py in yourapp.templatetags package, and use `{% load row_perms %}` at your template.

  • template
  • templatetag
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Custom CSS class in Form with template tag filter

A lot of times we need to insert a specific **CSS class** into a Form instance for it to be rendered in the template. The current method is to specify the CSS class in the Python code through the form field widget. But it would be easier for the designer to be able to specify the CSS class in the template directly. For example rather than doing this in your Python code: 'name = forms.CharField(widget=forms.TextInput(attrs={'class':'special'}))` You can do this in your template: `{{ form.name|cssclass:"special"}}` This template filter only works with Form Field instance.

  • css
  • form
  • class
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Template tag to create mailto links with options

A {% mailto %}{% endmailto %} template tag that requires an e-mail destination and optionally accepts subject, cc and bcc. It will then wrap whatever is within the tag in an `<a href="mailto:..."> </a>` HTML tag. See the docstring in the code for the {% mailto %} usage and some examples. You will need to load this template tag to your template. You can find detailed instructions [here](http://docs.djangoproject.com/en/dev/howto/custom-template-tags/#code-layout). But in a nutshell: 1. Create a templatetags package (meaning a directory with a __init__.py file in it) on the same level as your application's model.py 2. Put the code for this tag in a module (example: extra_tags.py) 3. On your template use {% load extra_tags %} -- note: the app where the templatetags package was created needs to be in INSTALLED_APPS 4. Use {% mailto user.email 'You subject here for {{user.get_full_name}}' %}blah{% endmailto %} This is my first django template tag. I am also NOT tremendously experienced with Python. Criticism and corrections are more than welcome.

  • template
  • tag
  • templatetag
  • email
  • mailto
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Models with database views

This example shows, how to use database views with django models. NewestArticle models contains 100 newest Articles. Remember, that NewestArticle model is read-only. Tested with mysql.

  • sql
  • models
  • views
  • view
  • model
  • mysql
  • database
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CodeLookupField

This is a custom form-field designed to make those optional "enter a discount code" fields a little easier to deal with. You create one like this: code = CodeLookupField(model=MyModel, field_name='slug', max_length=20) And then when you validate your form, cleaned_data['code'] will be the actual object if anything was retrieved, or None if the user entered a bad piece of data.

  • forms
  • field
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Captcha without Freetype or the Python Imaging Library (PIL)

If, like me, you've had trouble installing the [Python Imaging Library](http://www.pythonware.com/products/pil/) or [FreeType](http://freetype.sourceforge.org), you may have also had trouble getting a captcha to work. Here's my quick and dirty workaround — be warned, this is _very_ low level security, and shouldn't be used on high-profile sites. Originally published at <http://gregbrown.co.nz/code/django-captcha-without-freetype-or-pil/> Credit to the author of [django-simple-captcha](http://code.google.com/p/django-simple-captcha/), from whom I borrowed most of this code. ### Usage from django import forms from ABOVE-FILE import CaptchaField class CaptchaTestForm(forms.Form): myfield = forms.TextField() security_check = CaptchaField()

  • captcha
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partial tag

This is another partial tag, taken from a previous partial tag. The previous one assumed template locations by hardcoding in "partials/%s", etc. I took all that out, and made it work. And I took out the not needed third parameter for passing in your own data So now you call like this: {% partial "partials/mypartial.html" %} It passes the template context var into the partial, so anything you do in the main template, will work in the partial Just make sure you've got all the right imports.

  • tag
  • python
  • partial
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web-key: Base64 Shared Secret for Access Control

At the [Internet Identity Workshop](http://iiw.idcommons.net/Iiw8) in May, 2009, I spoke to Alan Karp and Tyler Close of HP Labs about their research on authorization without identity. Here are my [Delicious links](http://delicious.com/sbwms/ZBAC) on the subject. This led me to write code to generate a "web-key," the shared secret needed to implement the access control method discussed. In his paper, Tyler Close recommends 70 bits for the shared secret, encoded as a 13-character Base32 string. I used 72 bits, so the secret is a 12-character, URL-safe Base64 string without padding characters. I'm new to Python and Django, so I welcome refinements!

  • password
  • web-key
  • webkey
  • zbac
  • access-control
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Author: sbw
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