sublist
*Usage:* `list|sublist:"a:b"` Returns `list[a:b]` Accepts `":b"` and `"a:"` shortcuts Note that the double quotes are necessary
- filter
- lists
- templates
Snippet List
Recaptcha with Django Comments
Working off b23's [recaptcha support](http://www.djangosnippets.org/snippets/433/), I have hacked a way to add recaptcha support using existing comments. I am sure there is a better way, and ultimately I will suggest a patch to add captcha support as an option, but for now I hope this helps. For a more detailed rundown (as well as a working sample), check out my [blog entry](http://nikolajbaer.us/blog/recaptcha-django-free-comments/).
- comments
- recaptcha
Update only selected model fields
Watch out! Previous versions of this snippet (without the values list) were vulnerable to SQL injection attacks. The "correct" solution is probably to wait until [ticket 4102](http://code.djangoproject.com/ticket/4102) hits the trunk. But here's my temporary fix while we wait for that happy day. Django's model.save() method is a PITA: 1. It does a SELECT first to see if the instance is already in the database. 2. It has additional database performance overhead because it writes all fields, not just the ones that have been changed. 3. It overwrites other model fields with data that may be out of date. This is a real problem in concurrent applications, like almost all web apps. If you just want to update a field or two on a model instance which is already in the database, try this: update_fields(user, email='[email protected]', is_staff=True, last_login=datetime.now()) Or you can add it to your models (see below) and then do this: user.update_fields( email='[email protected]', is_staff=True, last_login=datetime.now()) To add it to your model, put it in a module called granular_update, then write this in your models.py: import granular_update class User(models.Model): email = models.EmailField() is_staff = models.BooleanField() last_login = models.DateTimeField() update_fields = granular_update.update_fields
- fields
- model
- save
- performance
- field
- update
- integrity
- consistency
Select multiple using a manytomany checkbox
Usage: from yourapp.fields import CheckBoxManyToMany from django.db import models class Weekday(models.Model): name = models.CharField() def __unicode__(self): return self.name class EventWithWeekday(models.Model): weekdays = CheckBoxManyToMany(Weekday)
- checkbox
- multiple
- oldforms
- select
Another means of updating a subset of a model's fields
Based on the UPDATE query section of `Model.save()`, this is another means of limiting the fields which are used in an UPDATE statement and bypassing the check for object existence which is made when you use `Model.save()`. Just make whatever changes you want to your model instance and call `update`, passing your instance and the names of any fields to be updated. Usage example: import datetime from forum.models import Topic from forum.utils.models import update topic = Topic.objects.get(pk=1) topic.post_count += 1 topic.last_post_at = datetime.datetime.now() update(topic, 'post_count', 'last_post_at') (Originally intended as a comment on [Snippet 479](/snippets/479/), but comments aren't working for me)
- model
- db
- update
Table of Contents
Simple template filter that extracts from a text ids, replaces '_' with spaces and produces hyperlinked Table of Contents. More info and usage example please see at [http://www.mysoftparade.com/blog/autogenerated-toc/](http://www.mysoftparade.com/blog/autogenerated-toc/)
- toc
- table-of-contents
Filter for adding quote marks
A template filter for adding curly quotes around a string. The filter understands enough HTML to put the quotes inside an initial paragraph begin and ending paragraph end, if they exist. Put the code inside a file in a templatetags subdir in your app, add a {% load myfile %} statement and you're ready to go with {{somebodysays|addquotes}}. Of course, beware the script kiddies, be careful with escaping.
- templatetag
- quotes
Renderer decorator
You can use this as a decorator for your views, this way you can return a simple dictionary and the decorator will do the rest. **@TODO:** Automatically set the template based on the app/view request
- shortcut
- render
Pattern to integer list function
This function can be util for transform pattern strings like these to list: >>> pattern_to_list('42-45') [42, 43, 44, 45] >>> pattern_to_list('15,49-52') [15, 49, 50, 51, 52] >>> pattern_to_list('0-13') [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13] You can use also the list to pattern function at [http://www.djangosnippets.org/snippets/496/](http://www.djangosnippets.org/snippets/496/)
- list
- integer
Integer list to pattern function
This function can be util for transform pattern lists like these to strings: >>> list_to_pattern([42, 43, 44, 45]) '42-45' >>> list_to_pattern([15, 49, 50, 51, 52]) '15,49-52' >>> list_to_pattern([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]) '0-13' You can use also the pattern to list function at [http://www.djangosnippets.org/snippets/495/](http://www.djangosnippets.org/snippets/495/)
- list
- integer
SeparatedValuesField
A Django newforms field which takes another newforms field during initialization and validates every item in a comma-separated list with this field class. Please use it like this: from django.newforms import EmailField emails = CommaSeparatedValuesField(EmailField) You would be able to enter a string like "[email protected],[email protected]" because every email address would be validated when clean() is executed. This of course also applies to any other Field class. You can define the sepator (default: ",") during initialization with the `separator` parameter like this: from django.newforms import EmailField` emails = SeparatedValuesField(EmailField, separator="###")
- newforms
- field
- comma
- separated
function_tag
register any python function as a tag with an optional name. usage: in templatetags: @function_tag() def foo(arg): return do_something(arg) in template: {% foo arg %} or {% foo arg as variable %}{{ variable.bar }}
- tag
- function
Cache Manager
I had a problem: too many fetches from the DB. So, how to reduce load on the database without major changes to the code? Cache Manager is the answer. I've managed to reduce number of DB hits as much as 80% in some cases (dictionaries, complex relations). It is using standard cache mechanisms. I'm using it with mathopd. This is a very simple solution, instead of standard Manager, put this in your model definition as: `objects = CacheManager()` Then everythere elase in the code instead of all() or get(...) call all_cached() or get_cached(). I've kept original methods intact, to have an dual access, when you really, really must have frest data from the DB, and you can't wait for cache to expire. This is much easier to work with, then manually getting fetched data from the cache.No change to your existing code 9except model) and voila! Additionally if you have some data, you would like to store with your serialized object (e.g. related data, dynamic dictionaries), you can do this in the model method '_init_instance_cache'). Drop me an email if you find this useful. :)
- cache
- model
- manager
blocksetter
Sometimes you need to set a little bit more complex variable in the template (e.g. Title), that is being used more than once. this simple tag defines "blockset" tag. {% blockset variable-name %}{%endblockset} everything inside body (between blockset/endblockset) is being assigned to the variable "variable-name". I have found this quite useful with translations, or setting the title, where you out several variables into one sentence. Drop me an email if you will find this useful.
- templatetag
- block
- set
NewForms Readonly / Edit Pattern
This is a little base class that I use to display forms in a readonly mode. Providing a simple javascript on the front end to allow a user to click an **edit** link that will show/hide the actual form. To use it simply inherit from it. Then in your templates do the following: `{{ form.as_readonly_table }}` **Other Notes** * **form.html** `{% for field in bound_fields %} {% include "newforms/field.html" %} {% endfor %}` * **field.html** `{% if field.errors %} <tr> <td> </td> <td>{{ field.errors }}</td> </tr> {% endif %} <tr> <th style="text-align:right"> <label for="id_{{ field.name }}">{{ field.label }}{% if field.field.required %}<span class="required"><sup>*</sup></span>{% endif %}</label> </th> <td>{{ field }} {% if field.help_text %} <p class="helptext">({{ field.help_text }})</p> {% endif %} </td> </tr>`
- template
- newforms
- readonly
- edit-mode