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aed1b1f6e5
If importing or initializing a template backend fails, attempting to
access this template backend again must raise the same exception.
Backport of 44ad6915 from master
132 lines
4.7 KiB
Python
132 lines
4.7 KiB
Python
from collections import Counter, OrderedDict
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import os
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import sys
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import warnings
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from django.apps import apps
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from django.conf import settings
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from django.core.exceptions import ImproperlyConfigured
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from django.utils import lru_cache
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from django.utils import six
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from django.utils.deprecation import RemovedInDjango20Warning
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from django.utils.functional import cached_property
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from django.utils.module_loading import import_string
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class InvalidTemplateEngineError(ImproperlyConfigured):
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pass
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class EngineHandler(object):
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def __init__(self, templates=None):
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"""
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templates is an optional list of template engine definitions
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(structured like settings.TEMPLATES).
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"""
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self._templates = templates
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self._engines = {}
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@cached_property
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def templates(self):
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if self._templates is None:
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self._templates = settings.TEMPLATES
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if not self._templates:
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warnings.warn(
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"You haven't defined a TEMPLATES setting. You must do so "
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"before upgrading to Django 2.0. Otherwise Django will be "
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"unable to load templates.", RemovedInDjango20Warning)
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self._templates = [
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{
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'BACKEND': 'django.template.backends.django.DjangoTemplates',
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'DIRS': settings.TEMPLATE_DIRS,
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'OPTIONS': {
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'allowed_include_roots': settings.ALLOWED_INCLUDE_ROOTS,
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'context_processors': settings.TEMPLATE_CONTEXT_PROCESSORS,
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'loaders': settings.TEMPLATE_LOADERS,
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'string_if_invalid': settings.TEMPLATE_STRING_IF_INVALID,
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},
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},
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]
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templates = OrderedDict()
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for tpl in self._templates:
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tpl = tpl.copy()
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try:
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# This will raise an exception if 'BACKEND' doesn't exist or
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# isn't a string containing at least one dot.
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default_name = tpl['BACKEND'].rsplit('.', 2)[-2]
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except Exception:
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invalid_backend = tpl.get('BACKEND', '<not defined>')
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raise ImproperlyConfigured(
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"Invalid BACKEND for a template engine: {}. Check "
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"your TEMPLATES setting.".format(invalid_backend))
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tpl.setdefault('NAME', default_name)
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tpl.setdefault('DIRS', [])
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tpl.setdefault('APP_DIRS', False)
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tpl.setdefault('OPTIONS', {})
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templates[tpl['NAME']] = tpl
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counts = Counter(list(templates))
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duplicates = [alias for alias, count in counts.most_common() if count > 1]
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if duplicates:
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raise ImproperlyConfigured(
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"Template engine aliases aren't unique, duplicates: {}. "
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"Set a unique NAME for each engine in settings.TEMPLATES."
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.format(", ".join(duplicates)))
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return templates
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def __getitem__(self, alias):
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try:
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return self._engines[alias]
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except KeyError:
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try:
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params = self.templates[alias]
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except KeyError:
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raise InvalidTemplateEngineError(
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"Could not find config for '{}' "
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"in settings.TEMPLATES".format(alias))
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# If importing or initializing the backend raises an exception,
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# self._engines[alias] isn't set and this code may get executed
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# again, so we must preserve the original params. See #24265.
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params = params.copy()
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backend = params.pop('BACKEND')
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engine_cls = import_string(backend)
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engine = engine_cls(params)
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self._engines[alias] = engine
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return engine
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def __iter__(self):
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return iter(self.templates)
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def all(self):
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return [self[alias] for alias in self]
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@lru_cache.lru_cache()
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def get_app_template_dirs(dirname):
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"""
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Return an iterable of paths of directories to load app templates from.
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dirname is the name of the subdirectory containing templates inside
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installed applications.
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"""
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if six.PY2:
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fs_encoding = sys.getfilesystemencoding() or sys.getdefaultencoding()
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template_dirs = []
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for app_config in apps.get_app_configs():
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if not app_config.path:
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continue
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template_dir = os.path.join(app_config.path, dirname)
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if os.path.isdir(template_dir):
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if six.PY2:
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template_dir = template_dir.decode(fs_encoding)
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template_dirs.append(template_dir)
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# Immutable return value because it will be cached and shared by callers.
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return tuple(template_dirs)
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