Question

Is there a lower-level way to provide the list of loaders when rendering a template, as opposed to always having Django use the setting?

I’d like to use a custom template loader instance for only a few views (I have my reasons).

Answer 1

It looks like you’ll have to write some code of your own to do it. Let’s take a look at the normal code path for loading templates, if you use, say, render_to_response, where the relevant part of the source is:

return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)

That’s a call to django.template.loader.render_to_string, which passes through some other functions and eventually ends up calling find_template.

The first time find_template is called, in initializes the global template_source_loaders cache based on settings.TEMPLATE_LOADERS. So it looks like there’s no just extra argument you can pass in or anything like that.

One possibility might be to add some loaders to django.template.loader.template_source_loaders just for the duration of that view. I don’t know if that will cause other problems; it feels dirty, but if it works, it’ll be pretty easy. (Just make a view decorator that does it.)

If you don’t want to do that, it looks like you’ll have to replicate the work of render_to_string with your own code (if you’re really sure you want to use per-view template loaders, which I’m accepting as a premise for the sake of this question but I bet isn’t actually necessary). There’s not all that much code there, and if you know in advance a specific loader and a single template name that you want to use, it’s actually pretty easy. (This is untested but will probably pretty much work.)

 def render_to_response_with_loader(loader, name,
           dictionary=None, context_instance=None, mimetype=None, dirs=None):

    # from find_template
    t, display_name = loader(name, dirs)

    # from get_template
    if not hasattr(t, 'render'):
        # template needs to be compiled
        t = django.template.loader.get_template_from_string(t, origin, template_name)

    # from render_to_string
    if not context_instance:
        rendered = t.render(Context(dictionary))
    else:
        # Add the dictionary to the context stack, ensuring it gets removed again
        # to keep the context_instance in the same state it started in.
        context_instance.update(dictionary)
        try:
            rendered = t.render(context_instance)
        finally:
            context_instance.pop()

     # from render_to_response
     return HttpResponse(rendered, mimetype=mimetype)

If you want to support multiple possible loaders or a list of possible filenames, just copy the relevant code from django.template.loader.