django1/django/template/utils.py

132 lines
4.7 KiB
Python

import os
import sys
import warnings
from collections import Counter, OrderedDict
from django.apps import apps
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.utils import lru_cache, six
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.functional import cached_property
from django.utils.module_loading import import_string
class InvalidTemplateEngineError(ImproperlyConfigured):
pass
class EngineHandler(object):
def __init__(self, templates=None):
"""
templates is an optional list of template engine definitions
(structured like settings.TEMPLATES).
"""
self._templates = templates
self._engines = {}
@cached_property
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 2.0. Otherwise Django will be "
"unable to load templates.", RemovedInDjango20Warning)
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()
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
counts = Counter(list(templates))
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
def __getitem__(self, alias):
try:
return self._engines[alias]
except KeyError:
try:
params = self.templates[alias]
except KeyError:
raise InvalidTemplateEngineError(
"Could not find config for '{}' "
"in settings.TEMPLATES".format(alias))
# If importing or initializing the backend raises an exception,
# self._engines[alias] isn't set and this code may get executed
# again, so we must preserve the original params. See #24265.
params = params.copy()
backend = params.pop('BACKEND')
engine_cls = import_string(backend)
engine = engine_cls(params)
self._engines[alias] = engine
return engine
def __iter__(self):
return iter(self.templates)
def all(self):
return [self[alias] for alias in self]
@lru_cache.lru_cache()
def get_app_template_dirs(dirname):
"""
Return an iterable of paths of directories to load app templates from.
dirname is the name of the subdirectory containing templates inside
installed applications.
"""
if six.PY2:
fs_encoding = sys.getfilesystemencoding() or sys.getdefaultencoding()
template_dirs = []
for app_config in apps.get_app_configs():
if not app_config.path:
continue
template_dir = os.path.join(app_config.path, dirname)
if os.path.isdir(template_dir):
if six.PY2:
template_dir = template_dir.decode(fs_encoding)
template_dirs.append(template_dir)
# Immutable return value because it will be cached and shared by callers.
return tuple(template_dirs)