| """ |
| Wrapper class that takes a list of template loaders as an argument and attempts |
| to load templates from them in order, caching the result. |
| """ |
| |
| from django.core.exceptions import ImproperlyConfigured |
| from django.template.base import TemplateDoesNotExist |
| from django.template.loader import BaseLoader, get_template_from_string, find_template_loader, make_origin |
| from django.utils.hashcompat import sha_constructor |
| from django.utils.importlib import import_module |
| |
| class Loader(BaseLoader): |
| is_usable = True |
| |
| def __init__(self, loaders): |
| self.template_cache = {} |
| self._loaders = loaders |
| self._cached_loaders = [] |
| |
| @property |
| def loaders(self): |
| # Resolve loaders on demand to avoid circular imports |
| if not self._cached_loaders: |
| for loader in self._loaders: |
| self._cached_loaders.append(find_template_loader(loader)) |
| return self._cached_loaders |
| |
| def find_template(self, name, dirs=None): |
| for loader in self.loaders: |
| try: |
| template, display_name = loader(name, dirs) |
| return (template, make_origin(display_name, loader, name, dirs)) |
| except TemplateDoesNotExist: |
| pass |
| raise TemplateDoesNotExist(name) |
| |
| def load_template(self, template_name, template_dirs=None): |
| key = template_name |
| if template_dirs: |
| # If template directories were specified, use a hash to differentiate |
| key = '-'.join([template_name, sha_constructor('|'.join(template_dirs)).hexdigest()]) |
| |
| if key not in self.template_cache: |
| template, origin = self.find_template(template_name, template_dirs) |
| if not hasattr(template, 'render'): |
| try: |
| template = get_template_from_string(template, origin, template_name) |
| except TemplateDoesNotExist: |
| # If compiling the template we found raises TemplateDoesNotExist, |
| # back off to returning the source and display name for the template |
| # we were asked to load. This allows for correct identification (later) |
| # of the actual template that does not exist. |
| return template, origin |
| self.template_cache[key] = template |
| return self.template_cache[key], None |
| |
| def reset(self): |
| "Empty the template cache." |
| self.template_cache.clear() |
