Custom template filter not working

Question

views.py

from django import template
register = template.Library()

@register.filter
def truncatesmart(value, limit=80):
    """
    Truncates a string after a given number of chars keeping whole words.

    Usage:
        {{ string|truncatesmart }}
        {{ string|truncatesmart:50 }}
    """

    try:
        limit = int(limit)
    # invalid literal for int()
    except ValueError:
        # Fail silently.
        return value

    # Make sure it's unicode
    value = unicode(value)

    # Return the string itself if length is smaller or equal to the limit
    if len(value) <= limit:
        return value

    # Cut the string
    value = value[:limit]

    # Break into words and remove the last
    words = value.split(' ')[:-1]

    # Join the words and return
    return ' '.join(words) + '...'

html

{% block content %}

<div class="container-fluid">
    <div class="container" id="content">
        <div class="span3">
            <div class="dashboard">
                <div class="well smooth-edge2 shadow">
                    <div class="mini-info">
                        <div class="username">
                            <h2 class="text-center">{{rest.name|truncatesmart}}</h2>

{% endblock %}

error

TemplateSyntaxError at /rprofile/info
Invalid filter: 'truncatesmart'

doubt

I am not able to understand why this custom filter is not working. While all other predefined filters such as title are working, this custom filter is not working at all.

Answer 1

According to the documentation:

For example, if your custom tags/filters are in a file called poll_extras.py, your app layout might look like this:

polls/
    models.py
    templatetags/
        __init__.py
        poll_extras.py
    views.py

---

You have defined your templatefilter in views.py. It should be there:

yourapp/templatetags/__init__.py
yourapp/templatetags/yourapp_tags.py

First, create yourapp/templatetags/ folder, and yourapp/templatetags/__init__.py empty file. Put your templatetag definition in yourapp_tags.py in that folder.

---

And in your template you would use the following:

{% load poll_extras %}

---

Finally, in your template, put {% load yourapp_tags %} to enable the templatetag.