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All snippets written in Python

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Binding pre-existing tables with dynamically created class models

This snippet proposes a solution for pre-exisiting database tables that have no counterpart in your django application models.py module. My use case was a comercial systems where pricing tables were created on-the-fly as a result of a stored procedure's execution inside the database. These pricing tables had no counterpart class model. Therefore, to access these tables from Python code you had to bypass Django's ORM and use plain-old SQL through cursos.execute(). This snippet's strategy is to create a (model) class on the fly and inject that class inside models.py namespace. After that you can use the generated class and Django's ORM machinery to access the tables, as if they were created by syncdb.

  • orm
  • dynamic-model
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Regular Expression Dictionary

Cute little dictionary-like object that stores keys as regexs and looks up items using regex matches. It actually came in handy for a project where keys were regexes on URLs.

  • regex
  • re
  • dict
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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
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Fuzzy Time of Day

This filter will display the time as word(s) indicating roughly the time of day ("Morning", "Afternoon", "Evening", etc). For example, the following template snippet: Posted in the {{ post.date|fuzzy_time }} of {{ post.date|date:"F j, Y"} }}. will result in the following (assuming `post.date == datetime.datetime(2007, 6, 13, 20, 57, 55, 765000)`): Posted in the evening of June 13, 2007. The terms used and breakpoints (hours only) can be rather arbitrary so you may want to adjust them to your liking. See the docs for [bisect][] for help in understanding the code. Just remember you should have one less breakpoint than periods and the first breakpoint falls at the end of the first period. The idea was inspired by [Dunstan Orchard][1], although the code is *very* different (php case statement). He uses quite a bit more periods in a day, so you might want to take a look. [bisect]: http://docs.python.org/lib/module-bisect.html [1]: http://www.1976design.com/blog/archive/2004/07/23/redesign-time-presentation/

  • template
  • filter
  • time
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locale based on domain

This is something we're using over at Curse to keep things clean and simple for our users. * We needed a url for any language code (which the domain provides) vs a cookie * We needed a to only store 2 letter codes in the db for each language (thus the key doesn't always match the code) This consists of two major modifications: * LANGUAGES in settings.py is a completely different format and would need changed based on your setup * the locale middleware has a couple absolute instances of where to point a user by default.

  • middleware
  • i18n
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Add validation for 'unique' and 'unique_together' constraints to newforms created dynamically via form_for_model or form_for_instance

This snippet provides a form_for_model and form_for_instance function which create newforms that respect the unique and unique_together constraints defined in the model. One thing about the coding style in this code snippet: Classes are capitalized even if they're passed as arguments. Thus "Model" is a model class while "model" is a model instance.

  • newforms
  • form_for_model
  • form_for_instance
  • unique_together
  • unique
  • formfield_factory
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Crop and scale image to a given size

Prerequisites: [Python Imaging Library](http://www.pythonware.com/products/pil/) This function scales a given image (provided as binary data in any format the PIL supports) to a specified size. If the force parameter is True, the function makes sure that the resulting image is exactly the specified size, cropping and scaling it as necessary (but never distorting it) to make sure the whole image area is filled out. If force is False, it simply uses the thumbnail function provided by the PIL, which preserves the image aspect ratio and does not increase the image dimensions beyond those of the original file, so you may not get an image that has the exact dimensions you specified. The result image is returned as JPEG data.

  • thumbnail
  • crop
  • scale
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Author: rpw
  • 3
  • 22

Truncate Characters Filter (simple)

Super stripped down filter to truncate after a certain number of letters. Ex: {{ long_blurb|truncchar:20 }} will display 20 characters of the long blurb followed by "..."

  • filter
  • letters
  • characters
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Avoid IE Brokenness When using Vary and Attachments

Apparently Internet Explorer (6 and 7) have a bug whereby if you blindly attach a PDF or some other file, it will choke. The problem lies in the Vary header (bug described in http://support.microsoft.com/kb/824847/en-us?spid=8722&sid=global). To use, just add to the beginning of your middleware classes.

  • middleware
  • ie
  • vary
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Random-image template tag

This tag makes it easy to have a random rotation of images on a page. Don't forget to set your MEDIA_URL.

  • template
  • image
  • random
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Author: pbx
  • 3
  • 12

Search results pagination

**Problem**: You search by firing POST and paginate by firing GET, so search results disappear on GET. I want to preserve searching results, so user can paginate them. First I try to use some static class to keep search results, but this solution has bug (thanks to svetlyak). In multiuser environment other user searching got results from previous one. No @cache_control(private=True) helps so I decided to change searching schema by using GET in the first place and to supply query string on each 'paging' request. Also added some memory cache that expires after 5 min **In template** Please append query to each paging link: <a href="?page={{ page_number }} &amp;search_query={{ query|urlencode }}"> {{ page_number }}</a> This snippet should keep search results on pagination in multiuser environment.

  • search
  • pagination
  • static-class
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Dynamic Form Class

Nutshell: Subclass this form with the required fields defined to automatically generate a form based on a model in a similar fashion to how form_for_model works, but in a way that tries to be a little easier if you want to customize the form. It handles updates and creations automatically as long as any database field requirements are met. This is something I made while trying to understand newforms, and is my own attempt at something between the simplicity of a stock form_for_model form, and a full blown custom form. The proper way is to use a callback function to customize form_for_model, but that felt cumbersome so I did it my way :) It works for me, but I'm relatively new to both python and Django so please test yourself before trusting.

  • dynamic
  • forms
  • subclass
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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
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Honeypot Field

Simple anti-spam field which will cause the form to raise a `ValidationError` if the value in this field changes. Displays as a CSS hidden `<input type="text" />` field. If you specify a `class` in the `attrs` of the widget, the default `style="display:none;"` won't be rendered with the widget so that you can use a predefined CSS style to do your hiding instead. You can also cause the widget to be wrapped in an html comment to ensure it is not visible to the end user: class EmailForm(Form): email = EmailField() website = HoneypotField(widget=HoneypotWidget( attrs={'class':'fish'}, html_comment=True))

  • spam
  • anti-spam
  • bot
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