How to repeat a "block" in a django template

DZPM_30300 0
Viewed 50138

I want to use the same {% block %} twice in the same django template. I want this block to appear more than once in my base template:

# base.html
<html>
    <head>
        <title>{% block title %}My Cool Website{% endblock %}</title>
    </head>
    <body>
        <h1>{% block title %}My Cool Website{% endblock %}</h1>
    </body>
</html>

And then extend it:

# blog.html
{% extends 'base.html' %}
{% block title %}My Blog{% endblock %}

# pictures.html
{% extends 'base.html' %}
{% block title %}My Pictures{% endblock %}

# cats.html
{% extends 'base.html' %}
{% block title %}My Cats{% endblock %}

I will get an exception, as Django wants the block to appear only once:

TemplateSyntaxError at /

'block' tag with name 'title' appears more than once

A quick and dirty solution would be duplicating the block title into title1 and title2:

# blog.html
{% extends 'base.html' %}
{% block title1 %}My Blog{% endblock %}
{% block title2 %}My Blog{% endblock %}

But this is a violation of the DRY principle. It would be very difficult as I have a lot of inheriting templates, and also because I don't wanna go to hell ;-)

Is there any trick or work-around to this problem? How can I repeat the same block in my template, without duplicating all the code?

dry django-templates django
14 Answers

I think that use of the context processor is in this case an overkill. You can easily do this:

#base.html
<html>
    <head>
        <title>{% block title %}My Cool Website{% endblock %}</title>
    </head>
    <body>
        {% block content %}{% endblock %}
    </body>
</html>

and then:

# blog.html
{% extends 'base.html' %}
{% block content %}
    <h1>{% block title %}My Blog{% endblock %}</h1>
    Lorem ipsum here...
{% endblock %}

and so on... Looks like DRY-compatible.

user_965690

You probably don't actually want to use a block but rather to just use a variable:

# base.html
<html>
    <head>
        <title>{{ title|default:"My Cool Website" }}</title>
    </head>
    <body>
        <h1>{{ title|default:"My Cool Website" }}</h1>
    </body>
</html>

You then set the title through the context.

zacherates_26030

you can use {% include subtemplate.html %} more than once. it's not the same as blocks, but does the trick.

Javier_116490
user_4559050

Building on Van Gale's suggestion, you could create get and set tags by adding the following to your templatetags.py file:

register = template.Library()

Stateful = {}
def do_set(parser, token):
    _, key = token.split_contents()
    nodelist = parser.parse(('endset',))
    parser.delete_first_token()  # from the example -- why?
    return SetStatefulNode(key,nodelist)

class SetStatefulNode(template.Node):
    def __init__(self, key, nodes):
        Stateful[key] = nodes
    def render(self, context):
        return ''
register.tag('set', do_set)

def do_get(parser, token):
    tag_name, key = token.split_contents()
    return GetStatefulNode(key)

class GetStatefulNode(template.Node):
    def __init__(self, key):
       self.key = key
    def render(self, context):
        return ''.join( [x.render(context) for x in Stateful[self.key]] )

register.tag('get', do_get)

Then set values in one template via {% set foo %}put data here{% endset %} and get them via {% get foo %} in another.

user_2466300

There are two easy solutions for this.

The easiest is to put your title into a context variable. You would set the context variable in your view.

If you are using something like generic views and don't have a views.py for pictures, cats, etc. then you can go the way of a custom template tag that sets a variable in the context.

Going this route would enable you to do something like:

{% extends "base.html" %}
{% load set_page_title %}
{% page_title "My Pictures" %}
...

Then in your base.html:

...
{% block title %}{{ page_title }}{% endblock %}
...
<h1>{{ page_title }}</h1>
Van_Gale_342580

The selected answer alludes to an easy workaround to wrap one tag inside another in the child template to give them both the same value. I use this for social images like so.

Child template:

{% extends 'base.html' %}
...
{% block meta_image %}
{% block meta_image_secure %}
{% if object.cover_pic %}
{{ object.cover_pic.url }}
{% else %}
https://live-static.welovemicro.com/static/img/device-dark.png
{% endif %}
{% endblock %}
{% endblock %}
...

Then in the parent base.html:

...
<meta property="og:image" itemprop="image" content="{% block meta_image %}https://live-static.welovemicro.com/static/img/device-dark.png{% endblock %}">
<meta property="og:image:secure_url" itemprop="image" content="{% block meta_image_secure %}https://live-static.welovemicro.com/static/img/device-dark.png{% endblock %}">
...
user_69169000
Related