Django: How can I get a block from a template?

Question

Suppose my template has in it something like {% block subject %}my subject{% endblock %} and I load this template with tmpl = loader.get_template('mytemplate.html'), how can I extract "my subject"?

Answer 1

from django.template import Context
from django.template.loader import get_template
from django.template.loader_tags import BlockNode

t = get_template('template.html')
for node in t:
    if isinstance(node, BlockNode) and node.name == 'subject':
        print node.render(Context())

This worked for me, using Django 1.1.1

Answer 2

Camilo's solution doesn't work when your template extends a base. I've modified it a bit to (hopefully) fix that problem:

from django.template import Context
from django.template.loader import get_template
from django.template.loader_tags import BlockNode, ExtendsNode

def _get_node(template, context=Context(), name='subject'):
    for node in template:
        if isinstance(node, BlockNode) and node.name == name:
            return node.render(context)
        elif isinstance(node, ExtendsNode):
            return _get_node(node.nodelist, context, name)
    raise Exception("Node '%s' could not be found in template." % name)

I'm really not sure if this is the right way to recursively iterate over all the nodes... but it works in my limited case.