django: Invalid filter

Question

I got an article app and trying to make a custom filter, I have a directory called templatetags in article app, and a tags.py within that directory, here is the directory structure.

-manage.py(f)
-settings.py(f)
-articles(d)
 - templatetags(d)
  - tags.py(f)

On the templates, the articles have its own directory, all article templates extend from a base.html template, here is the template structure.

-base.html(f)
-articles(d)
 -index.html(f)

I load the tags in base.html {% load tags %} and use the custom filter in index.html and got the invalid filter error.

tags.py

from django import template                                                                                                                                                        
from django.template.defaultfilters import stringfilter

register = template.Library()

@register.filter
@stringfilter
def space2Dash(s):
    return s.replace(' ', '_');

I just can't figure out what I did wrong.

edit: I changed the filter name to abcfilter.py and I have the article app loaded in my settings.py

articles/index.html

 {% load abcfilter %}
 {{ "foo bar"|space2dash }}

the error:

Request Method: GET
Request URL:    http://localhost:8080/articles/
Django Version: 1.2.5
Exception Type: TemplateSyntaxError
Exception Value:    
Invalid filter: 'space2dash'
Exception Location: ***/lib/python2.7/django/template/__init__.py in find_filter, line 363
Python Executable:  /usr/local/bin/python
Python Version: 2.7.1
Server time:    Sun, 10 Apr 2011 07:55:54 -0500

Lorraine

Answer 1

First off remove the semicolon after your replace.

Do you have a file called __init__.py (this is suppose to have 2 underscores before and after init, hard to format in editor.) under the templatetags directory?

Here is a good page with lots of info if you haven't looked yet.

http://docs.djangoproject.com/en/dev/howto/custom-template-tags/

Clinton

Thanks for the answer, after remove the smeicolon, the error still there.(fyi, i have a empty init.py in templatetags directory and I have read the doc pages couple times, but I don't know what I did wrong) – Lorraine

Try to rename the file from tags to something else. Maybe tags is a reserved word. Do you have the articles app registered in your settings file? Can you post the exact error and the HTML that you are using to call the tag? – Clinton

I have change tags.py to abcfilter.py and check the above for the error and html in the template – Lorraine

Not sure if it is a typo when transfering to SO, but {{ "foo bar"|space2dash %} should be {{ "foo bar"|space2dash }} also your method is called space2Dash but you are referencing space2dash (all lowercase). – Clinton

Thanks Ken, I think I'm going to order a hat from amazon and eat it(the problem turn out to be I got a space2Dash, the capital D :) – Lorraine

Answer 2

Just for reference, I solved the problem by moving

{% load ... %}

from the base template to the concrete template. See also this post https://mcmap.net/q/428790/-django-problems-while-loading-custom-filters-in-the-base-template-file-while-using-template-inheritance

Crow

works for me. Putting it in base template seems doesn't work at all – Benford

I was having this same issue. Does anyone know why this happens? – Athanasius

load 3 dots? or load what? – Lucre

Answer 3

I was nearly going nuts with this problem and none of the above answers helped.

If you have several apps, make sure that the file names containing your custom tags/filters are unique, prefereablyapp_name_filters.py. Otherwise Django will only load the custom filters from the app it finds matching first!

Dowel

Thanks man! You triggered me to check it... My deployment routine doesn't delete old files on server. So it was working locally, and in testing, but not on server. I was lost. You saved me! – Calendre

Somehow even this doesn't work for me (and I'm only talking of the local environment). :( Django can be super weird sometimes. – Creativity

Answer 4

To avoid loading the module in each template using {% load MODULE_NAME %}, you can add it as a 'builtin' in settings.py:

TEMPLATES = [
    {
        'OPTIONS': {
            ...
            ,
            'builtins': [
                ...
                'APP_NAME.templatetags.MODULE_NAME',
                ]
        },
    },
]

Quadrangle