KeyError when using parameter on _() gettext function

[ripperdoc]

If I use the line

_('Regarding order %(order)s')|format(order=order.id)

I get a KeyError exception:

Traceback (most recent call last):
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/views.py", line 84, in view
    return self.dispatch_request(*args, **kwargs)
  File "/Users/martin/Dev/raconteur/resource.py", line 527, in dispatch_request
    return render_template(r['template'], **r)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/templating.py", line 128, in render_template
    context, ctx.app)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Flask-0.10.1-py2.7.egg/flask/templating.py", line 110, in _render
    rv = template.render(context)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Jinja2-2.7.2-py2.7.egg/jinja2/environment.py", line 969, in render
    return self.environment.handle_exception(exc_info, True)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Jinja2-2.7.2-py2.7.egg/jinja2/environment.py", line 742, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/martin/Dev/raconteur/templates/shop/order_item.html", line 3, in top-level template code
    {% import 'includes/macros.html' as MACRO %}
  File "/Users/martin/Dev/raconteur/templates/shop/_page.html", line 2, in top-level template code
    {% import 'includes/macros.html' as MACRO %}
  File "/Users/martin/Dev/raconteur/templates/_page.html", line 138, in top-level template code
    {% block mainblock %}
  File "/Users/martin/Dev/raconteur/templates/_page.html", line 148, in block "mainblock"
    {% block middle %}
  File "/Users/martin/Dev/raconteur/templates/_page.html", line 159, in block "middle"
    {% block content %}{% endblock %}
  File "/Users/martin/Dev/raconteur/templates/shop/order_item.html", line 26, in block "content"
    {% block content %}{% block inline %}
  File "/Users/martin/Dev/raconteur/templates/shop/order_item.html", line 33, in block "inline"
    {% set prefill_subject = safe(_('Regarding order %(order)s'))|format(order=order.id) %}
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Jinja2-2.7.2-py2.7.egg/jinja2/ext.py", line 132, in _gettext_alias
    return __context.call(__context.resolve('gettext'), *args, **kwargs)
  File "/Users/martin/Dev/rac2env/lib/python2.7/site-packages/Jinja2-2.7.2-py2.7.egg/jinja2/ext.py", line 141, in gettext
    return rv % variables
KeyError: u'order'

If I instead use the line:

gettext('Regarding order %(order)s', order=order.id)

I don't get this error. Why the difference? (edited for mistake in first code line)

[untitaker]

I think gettext is trying to resolve the formatting string itself.

[ripperdoc]

Just to add, the documentation lists both methods as OK, but only the second one works for me. http://jinja.pocoo.org/docs/dev/templates/#i18n

[snoack]

Here is the responsible code from jinja2/ext.py causing this:

def _make_new_gettext(func):
    @contextfunction
    def gettext(__context, __string, **variables):
        rv = __context.call(func, __string)
        if __context.eval_ctx.autoescape:
            rv = Markup(rv)
        return rv % variables
    return gettext

Jinja2 wraps the external gettext function inserting placeholders using the %-string-formatting. So if any placeholder value is absent in the keyword arguments rv % variables throws a KeyError of cause.

IMO this is fine. But I agree that the documentation needs to be corrected.

[davidism]

Looks like you have new-style gettext enabled, which makes string formatting part of the call rather than a separate step with the |format filter.

I added something to the docs about this.