Initial support for Jinja2.

CHANGELOG.rst

@@ -3,6 +3,12 @@
 Changelog
 #########
 
+0.4 (xxxx)
+==========
+
+*   Initial support for using the `Jinja2 <http://jinja.pocoo.org/>`_ templating
+    engine. See README for caveats.
+
 0.3.1 (June 1, 2016)
 ====================
 

README.rst

@@ -9,11 +9,18 @@ arbitrary template inheritance, even if a block is defined in the child template
 but not in the parent. Generally it works like ``render_to_string`` from Django,
 but allows you to specify a block to render.
 
+Features
+========
+
+*   Render a specific block from a template
+*   Fully supports the Django templating engine
+*   Partially supports the `Jinja2 <http://jinja.pocoo.org/>`_ engine: it does
+    not currently process the ``extends`` tag.
+
 Requirements
 ============
 
-Django Render Block supports Django 1.8 and 1.9. You must use the Django
-template rendering engine (the default) to render specific blocks.
+Django Render Block supports Django 1.8 and 1.9.
 
 Examples
 ========

render_block/base.py

@@ -2,6 +2,13 @@
 
 from django.template import loader
 from django.template.backends.django import Template as DjangoTemplate
+try:
+    from django.template.backends.jinja2 import Template as Jinja2Template
+except ImportError:
+    # Most likely Jinja2 isn't installed, in that case just create a class since
+    # we always want it to be false anyway.
+    class Jinja2Template(object):
+        pass
 
 from render_block.django import django_render_block
 from render_block.exceptions import BlockNotFound, UnsupportedEngine
@@ -30,6 +37,11 @@ def render_block_to_string(template_name, block_name, context=None):
     # The Django backend.
     if isinstance(t, DjangoTemplate):
         return django_render_block(t, block_name, context)
+
+    elif isinstance(t, Jinja2Template):
+        from render_block.jinja2 import jinja2_render_block
+        return jinja2_render_block(t, block_name, context)
+
     else:
         raise UnsupportedEngine(
             'Can only render blocks from the Django template backend.')

render_block/jinja2.py

@@ -0,0 +1,17 @@
+from render_block.base import BlockNotFound
+
+def jinja2_render_block(template, block_name, context):
+    # Get the underlying jinja2.environment.Template object.
+    template = template.template
+
+    # Create a new Context instance.
+    context = template.new_context(context)
+
+    # Try to find the wanted block.
+    try:
+        gen = template.blocks[block_name](context)
+    except KeyError:
+        raise BlockNotFound("block with name '%s' does not exist" % block_name)
+
+    # The result from above is a generator which yields unicode strings.
+    return u''.join([s for s in gen])

requirements.txt

@@ -4,3 +4,4 @@
 
 # Not tested with older versions of Django.
 Django==1.8.13
+Jinja2==2.8

tests/templates/test3_jinja2.html

@@ -0,0 +1,5 @@
+{% extends 'test1.html' %}
+
+{% block block1 %}{% include "include.html" %}{% endblock %}
+
+{% block block2 %}block2 from test3 - {{ super() }}{% endblock %}

tests/tests.py

@@ -1,11 +1,14 @@
+from unittest import skip
+
 from django.template import Context
 from django.test import override_settings, TestCase
 from django.utils import six
 
 from render_block import render_block_to_string, BlockNotFound, UnsupportedEngine
 
 
-class TestCases(TestCase):
+class TestDjango(TestCase):
+    """Test the Django templating engine."""
     def assertExceptionMessageEquals(self, exception, expected):
         result = exception.message if six.PY2 else exception.args[0]
         self.assertEqual(expected, result)
@@ -38,12 +41,12 @@ def test_no_block(self):
 
     def test_include(self):
         """Ensure that an include tag in a block still works."""
-        result = render_block_to_string('test3.html', 'block1')
+        result = render_block_to_string('test3_django.html', 'block1')
         self.assertEqual(result, u'included template')
 
     def test_super(self):
         """Test that block.super works."""
-        result = render_block_to_string('test3.html', 'block2')
+        result = render_block_to_string('test3_django.html', 'block2')
         self.assertEqual(result, u'block2 from test3 - block2 from test1')
 
     def test_subblock(self):
@@ -76,3 +79,69 @@ def test_different_backend(self):
             render_block_to_string('test1.html', 'noblock')
         self.assertExceptionMessageEquals(exc.exception,
                                           "Can only render blocks from the Django template backend.")
+
+
+@override_settings(
+    TEMPLATES=[{
+        'BACKEND': 'django.template.backends.jinja2.Jinja2',
+        'DIRS': ['tests/templates'],
+        'APP_DIRS': True,
+    },]
+)
+class TestJinja2(TestCase):
+    """Test the Django templating engine."""
+    def assertExceptionMessageEquals(self, exception, expected):
+        result = exception.message if six.PY2 else exception.args[0]
+        self.assertEqual(expected, result)
+
+    def test_block(self):
+        """Test rendering an individual block."""
+        result = render_block_to_string('test1.html', 'block1')
+        self.assertEqual(result, u'block1 from test1')
+
+        # No reason this shouldn't work, but just in case.
+        result = render_block_to_string('test1.html', 'block2')
+        self.assertEqual(result, u'block2 from test1')
+
+    def test_override(self):
+        """This block is overridden in test2."""
+        result = render_block_to_string('test2.html', 'block1')
+        self.assertEqual(result, u'block1 from test2')
+
+    @skip('Not currently supported.')
+    def test_inherit(self):
+        """This block is inherited from test1."""
+        result = render_block_to_string('test2.html', 'block2')
+        self.assertEqual(result, u'block2 from test1')
+
+    def test_no_block(self):
+        """Check if there's no block available an exception is raised."""
+        with self.assertRaises(BlockNotFound) as exc:
+            render_block_to_string('test1.html', 'noblock')
+        self.assertExceptionMessageEquals(exc.exception,
+                                          "block with name 'noblock' does not exist")
+
+    def test_include(self):
+        """Ensure that an include tag in a block still works."""
+        result = render_block_to_string('test3_jinja2.html', 'block1')
+        self.assertEqual(result, u'included template')
+
+    @skip('Not currently supported.')
+    def test_super(self):
+        """Test that super() works."""
+        result = render_block_to_string('test3_jinja2.html', 'block2')
+        self.assertEqual(result, u'block2 from test3 - block2 from test1')
+
+    def test_subblock(self):
+        """Test that a block within a block works."""
+        result = render_block_to_string('test5.html', 'block1')
+        self.assertEqual(result, u'block3 from test5')
+
+        result = render_block_to_string('test5.html', 'block3')
+        self.assertEqual(result, u'block3 from test5')
+
+    def test_context(self):
+        """Test that a context is properly rendered in a template."""
+        data = u'block2 from test5'
+        result = render_block_to_string('test5.html', 'block2', {'foo': data})
+        self.assertEqual(result, data)

tox.ini

@@ -11,6 +11,7 @@ passenv = TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH
 commands =
     python manage.py test
 deps =
+    Jinja2==2.8
     django18: Django>=1.8,<1.9
     django19: Django>=1.9,<1.10
     django110: https://codeload.github.com/django/django/zip/master