utils.py 文件源码

def templates(self):
        if self._templates is None:
            self._templates = settings.TEMPLATES

        if not self._templates:
            warnings.warn(
                "You haven't defined a TEMPLATES setting. You must do so "
                "before upgrading to Django 1.10. Otherwise Django will be "
                "unable to load templates.", RemovedInDjango110Warning)
            self._templates = [
                {
                    'BACKEND': 'django.template.backends.django.DjangoTemplates',
                    'DIRS': settings.TEMPLATE_DIRS,
                    'OPTIONS': {
                        'allowed_include_roots': settings.ALLOWED_INCLUDE_ROOTS,
                        'context_processors': settings.TEMPLATE_CONTEXT_PROCESSORS,
                        'debug': settings.TEMPLATE_DEBUG,
                        'loaders': settings.TEMPLATE_LOADERS,
                        'string_if_invalid': settings.TEMPLATE_STRING_IF_INVALID,
                    },
                },
            ]

        templates = OrderedDict()
        backend_names = []
        for tpl in self._templates:
            tpl = tpl.copy()
            try:
                # This will raise an exception if 'BACKEND' doesn't exist or
                # isn't a string containing at least one dot.
                default_name = tpl['BACKEND'].rsplit('.', 2)[-2]
            except Exception:
                invalid_backend = tpl.get('BACKEND', '<not defined>')
                raise ImproperlyConfigured(
                    "Invalid BACKEND for a template engine: {}. Check "
                    "your TEMPLATES setting.".format(invalid_backend))

            tpl.setdefault('NAME', default_name)
            tpl.setdefault('DIRS', [])
            tpl.setdefault('APP_DIRS', False)
            tpl.setdefault('OPTIONS', {})

            templates[tpl['NAME']] = tpl
            backend_names.append(tpl['NAME'])

        counts = Counter(backend_names)
        duplicates = [alias for alias, count in counts.most_common() if count > 1]
        if duplicates:
            raise ImproperlyConfigured(
                "Template engine aliases aren't unique, duplicates: {}. "
                "Set a unique NAME for each engine in settings.TEMPLATES."
                .format(", ".join(duplicates)))

        return templates