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from collections import defaultdict
from importlib import import_module
from pkgutil import walk_packages
from django.apps import apps
from django.conf import settings
from django.core.checks import Error, Warning
from django.template import TemplateDoesNotExist
from django.template.context import make_context
from django.template.engine import Engine
from django.template.library import InvalidTemplateLibrary
from .base import BaseEngine
class DjangoTemplates(BaseEngine):
app_dirname = "templates"
def __init__(self, params):
params = params.copy()
options = params.pop("OPTIONS").copy()
options.setdefault("autoescape", True)
options.setdefault("debug", settings.DEBUG)
options.setdefault("file_charset", "utf-8")
libraries = options.get("libraries", {})
options["libraries"] = self.get_templatetag_libraries(libraries)
super().__init__(params)
self.engine = Engine(self.dirs, self.app_dirs, **options)
def check(self, **kwargs):
return [
*self._check_string_if_invalid_is_string(),
*self._check_for_template_tags_with_the_same_name(),
]
def _check_string_if_invalid_is_string(self):
value = self.engine.string_if_invalid
if not isinstance(value, str):
return [
Error(
"'string_if_invalid' in TEMPLATES OPTIONS must be a string but "
"got: %r (%s)." % (value, type(value)),
obj=self,
id="templates.E002",
)
]
return []
def _check_for_template_tags_with_the_same_name(self):
libraries = defaultdict(set)
for module_name, module_path in get_template_tag_modules():
libraries[module_name].add(module_path)
for module_name, module_path in self.engine.libraries.items():
libraries[module_name].add(module_path)
errors = []
for library_name, items in libraries.items():
if len(items) > 1:
items = ", ".join(repr(item) for item in sorted(items))
errors.append(
Warning(
f"{library_name!r} is used for multiple template tag modules: "
f"{items}",
obj=self,
id="templates.W003",
)
)
return errors
def from_string(self, template_code):
return Template(self.engine.from_string(template_code), self)
def get_template(self, template_name):
try:
return Template(self.engine.get_template(template_name), self)
except TemplateDoesNotExist as exc:
reraise(exc, self)
def get_templatetag_libraries(self, custom_libraries):
"""
Return a collation of template tag libraries from installed
applications and the supplied custom_libraries argument.
"""
libraries = get_installed_libraries()
libraries.update(custom_libraries)
return libraries
class Template:
def __init__(self, template, backend):
self.template = template
self.backend = backend
@property
def origin(self):
return self.template.origin
def render(self, context=None, request=None):
context = make_context(
context, request, autoescape=self.backend.engine.autoescape
)
try:
return self.template.render(context)
except TemplateDoesNotExist as exc:
reraise(exc, self.backend)
def copy_exception(exc, backend=None):
"""
Create a new TemplateDoesNotExist. Preserve its declared attributes and
template debug data but discard __traceback__, __context__, and __cause__
to make this object suitable for keeping around (in a cache, for example).
"""
backend = backend or exc.backend
new = exc.__class__(*exc.args, tried=exc.tried, backend=backend, chain=exc.chain)
if hasattr(exc, "template_debug"):
new.template_debug = exc.template_debug
return new
def reraise(exc, backend):
"""
Reraise TemplateDoesNotExist while maintaining template debug information.
"""
new = copy_exception(exc, backend)
raise new from exc
def get_template_tag_modules():
"""
Yield (module_name, module_path) pairs for all installed template tag
libraries.
"""
candidates = ["django.templatetags"]
candidates.extend(
f"{app_config.name}.templatetags" for app_config in apps.get_app_configs()
)
for candidate in candidates:
try:
pkg = import_module(candidate)
except ImportError:
# No templatetags package defined. This is safe to ignore.
continue
if hasattr(pkg, "__path__"):
for name in get_package_libraries(pkg):
yield name.removeprefix(candidate).lstrip("."), name
def get_installed_libraries():
"""
Return the built-in template tag libraries and those from installed
applications. Libraries are stored in a dictionary where keys are the
individual module names, not the full module paths. Example:
django.templatetags.i18n is stored as i18n.
"""
return {
module_name: full_name for module_name, full_name in get_template_tag_modules()
}
def get_package_libraries(pkg):
"""
Recursively yield template tag libraries defined in submodules of a
package.
"""
for entry in walk_packages(pkg.__path__, pkg.__name__ + "."):
try:
module = import_module(entry[1])
except ImportError as e:
raise InvalidTemplateLibrary(
"Invalid template library specified. ImportError raised when "
"trying to load '%s': %s" % (entry[1], e)
) from e
if hasattr(module, "register"):
yield entry[1]
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