Include monkeypatch from nuggets. Fix #11.

README.rst

@@ -152,6 +152,15 @@ The other method uses Jinja's ``trans`` tag::
 directly.  Both methods are useful, pick the one that makes you happy.
 
 
+Forms
+-----
+
+Django marks its form HTML "safe" according to its own rules, which Jinja2 does
+not recognize.
+
+.. automodule:: jingo.monkey
+
+
 Testing
 -------
 

docs/index.rst

@@ -152,6 +152,15 @@ The other method uses Jinja's ``trans`` tag::
 directly.  Both methods are useful, pick the one that makes you happy.
 
 
+Forms
+-----
+
+Django marks its form HTML "safe" according to its own rules, which Jinja2 does
+not recognize.
+
+.. automodule:: jingo.monkey
+
+
 Testing
 -------
 

jingo/monkey.py

@@ -0,0 +1,85 @@
+"""
+This monkeypatches Django to support the __html__ protocol used in Jinja
+templates. Form, BoundField, ErrorList, and other form objects that
+render HTML through their __unicode__ method are extended with __html__
+so they can be rendered in Jinja templates without adding |safe.
+
+Call the patch() function to execute the patch. It must be called
+before django.forms is imported for the conditional_escape patch to work
+properly. The root URLconf is the recommended location for calling patch().
+
+Usage::
+
+    import jingo.monkey
+    jingo.monkey.patch()
+
+This patch was originally developed by Jeff Balogh and this version is taken
+from the nuggets project at
+https://github.com/mozilla/nuggets/blob/master/safe_django_forms.py
+
+"""
+import django.utils.encoding
+import django.utils.html
+import django.utils.safestring
+
+
+# This function gets directly imported within Django, so this change needs to
+# happen before too many Django imports happen.
+def conditional_escape(html):
+    """
+    Similar to escape(), except that it doesn't operate on pre-escaped strings.
+    """
+    if hasattr(html, '__html__'):
+        return html.__html__()
+    elif isinstance(html, django.utils.safestring.SafeData):
+        return html
+    return django.utils.html.escape(html)
+
+
+# Django uses SafeData to mark a string that has already been escaped or
+# otherwise deemed safe. This __html__ method lets Jinja know about that too.
+def __html__(self):
+    """
+    Returns the html representation of a string.
+
+    Allows interoperability with other template engines.
+    """
+    return self
+
+
+# Django uses StrAndUnicode for classes like Form, BoundField, Widget which
+# have a __unicode__ method which returns escaped html. We replace
+# StrAndUnicode with SafeStrAndUnicode to get the __html__ method.
+class SafeStrAndUnicode(django.utils.encoding.StrAndUnicode):
+    """A class whose __str__ and __html__ returns __unicode__."""
+
+    def __html__(self):
+        return unicode(self)
+
+
+def patch():
+    django.utils.html.conditional_escape = conditional_escape
+    django.utils.safestring.SafeData.__html__ = __html__
+
+    # forms imports have to come after we patch conditional_escape.
+    from django.forms import forms, formsets, util, widgets
+
+    # Replace StrAndUnicode with SafeStrAndUnicode in the inheritance
+    # for all these classes.
+    classes = (
+        forms.BaseForm,
+        forms.BoundField,
+        formsets.BaseFormSet,
+        util.ErrorDict,
+        util.ErrorList,
+        widgets.Media,
+        widgets.RadioInput,
+        widgets.RadioFieldRenderer,
+    )
+
+    for cls in classes:
+        bases = list(cls.__bases__)
+        if django.utils.encoding.StrAndUnicode in bases:
+            idx = bases.index(django.utils.encoding.StrAndUnicode)
+            bases[idx] = SafeStrAndUnicode
+            cls.__bases__ = tuple(bases)

jingo/tests/test_monkey.py

@@ -0,0 +1,24 @@
+from django import forms
+
+from jinja2 import escape
+from nose.tools import eq_
+
+import jingo
+import jingo.monkey
+from test_helpers import render
+
+
+class MyForm(forms.Form):
+    email = forms.EmailField()
+
+
+def test_monkey_patch():
+    form = MyForm()
+    html = form.as_ul()
+    context = {'form': form}
+    t = '{{ form.as_ul() }}'
+
+    eq_(escape(html), render(t, context))
+
+    jingo.monkey.patch()
+    eq_(html, render(t, context))

jingo/tests/urls.py

@@ -1,5 +1,6 @@
 from django.conf.urls.defaults import patterns
 
+
 urlpatterns = patterns('',
     (r'^url/(\d+)/(\w+)/$', lambda r: None, {}, "url-args"),
     (r'^url/(?P<num>\d+)/(?P<word>\w+)/$', lambda r: None, {}, "url-kwargs"),