django templates: include and extends

When you use the extends template tag, you're saying that the current template extends another -- that it is a child template, dependent on a parent template. Django will look at your child template and use its content to populate the parent.

Everything that you want to use in a child template should be within blocks, which Django uses to populate the parent. If you want use an include statement in that child template, you have to put it within a block, for Django to make sense of it. Otherwise it just doesn't make sense and Django doesn't know what to do with it.

The Django documentation has a few really good examples of using blocks to replace blocks in the parent template.

https://docs.djangoproject.com/en/dev/ref/templates/language/#template-inheritance

From Django docs:

The include tag should be considered as an implementation of "render this subtemplate and include the HTML", not as "parse this subtemplate and include its contents as if it were part of the parent". This means that there is no shared state between included templates -- each include is a completely independent rendering process.

So Django doesn't grab any blocks from your commondata.html and it doesn't know what to do with rendered html outside blocks.

This should do the trick for you: put include tag inside of a block section.

page1.html:

{% extends "base1.html" %}{% block foo %}   {% include "commondata.html" %}{% endblock %}

page2.html:

{% extends "base2.html" %}{% block bar %}   {% include "commondata.html" %}{% endblock %}