112 lines
3.5 KiB
Python
112 lines
3.5 KiB
Python
import functools
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from collections import Counter
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from pathlib import Path
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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.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:
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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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templates = {}
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backend_names = []
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for tpl in self._templates:
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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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)
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tpl = {
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"NAME": default_name,
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"DIRS": [],
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"APP_DIRS": False,
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"OPTIONS": {},
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**tpl,
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}
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templates[tpl["NAME"]] = tpl
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backend_names.append(tpl["NAME"])
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counts = Counter(backend_names)
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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.".format(
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", ".join(duplicates)
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)
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)
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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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)
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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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@functools.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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template_dirs = [
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Path(app_config.path) / dirname
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for app_config in apps.get_app_configs()
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if app_config.path and (Path(app_config.path) / dirname).is_dir()
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]
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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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