I've been working on a project where I realized that I wanted to call methods on Python objects *with arguments* from within a Django template.
As a silly example, let's say your application maintains users and "permissions" that have been granted to them. Say that permissions are open-ended, and new ones are getting defined on a regular basis. Your `User` class has a `check_permission(p)` method that return `True` if the user has been granted the permission `p`.
You want to present all the users in a table, with one row per user. You want to each permission to be presented as a column in the table. A checkmark will appear in cells where a user has been granted a particular permission. Normally, in order to achieve this, you'd need to cons up some sort of list-of-dicts structure in Python and pass that as a context argument. Ugh!
Here's how you'd use the `method`, `with`, and `call` filters to invoke the `check_permission` method from within your template. (Assume that you've provided `users` and `permissions` as context variables, with a list of user and permission objects, respectively.)
<table>
<tr>
<th></th>
{% for p in permissions %}
<th>{{ p.name }}</th>
{% endfor %}
</tr>
{% for u in users %}
<tr>
<td>{{ u.name }}</td>
{% for p in permissions %}
<td>
{% if user|method:"check_permission"|with:p|call" %}X{% endif %}
</td>
{% endfor %}
</tr>
{% endfor %}
</table>
The `call_with` method is a shortcut for single-argument invocation; for example, we could have re-written the above as
{% if user|method:"check_permission"|call_with:p %}...{% endif %}
Anyway, this has been useful for me. Hope it's helpful for others!
--chris
P.S., tip o' the cap to Terry Weissman for helping me polish the rough edges!
- filter
- filters
- function
- object
- method
I wanted to have the possibility to use a wiki-like markup style in my flatpages for various purposes (embedding images, quoting, etc.)
After a few dead ends I came up with this, which is quite nice I think.
> It basically takes a named tag, loads the corresponding template, passes in all arguments, renders the template and replaces the named tag with the result.
*The markup looks like this:*
> [[example:value to pass|option1=somevalue option2=values can have spaces too! without having to put them in quotes option3=some other value]]
*This results in:*
* Filter tries to load wiki/wiki_example.html
* If it is loaded, it passes an WikiElement containing the value and the options to the template, renders it and replaces the tag with the rendered template
*In the "wiki/wiki_example.html" template you can use it like this:*
{{param.value}}
{{param.opts.option1}}
Or loop over param.opts.iteritems.
- template
- filter
- markup
- wiki
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/