"""Jinja2 environment and extensions loading."""
from __future__ import annotations
from typing import Any
from jinja2 import Environment, StrictUndefined
from cookiecutter.exceptions import UnknownExtension
[docs]
class ExtensionLoaderMixin:
"""Mixin providing sane loading of extensions specified in a given context.
The context is being extracted from the keyword arguments before calling
the next parent class in line of the child.
"""
def __init__(self, *, context: dict[str, Any] | None = None, **kwargs: Any) -> None:
"""Initialize the Jinja2 Environment object while loading extensions.
Does the following:
1. Establishes default_extensions (currently just a Time feature)
2. Reads extensions set in the cookiecutter.json _extensions key.
3. Attempts to load the extensions. Provides useful error if fails.
"""
context = context or {}
default_extensions = [
'cookiecutter.extensions.JsonifyExtension',
'cookiecutter.extensions.RandomStringExtension',
'cookiecutter.extensions.SlugifyExtension',
'cookiecutter.extensions.TimeExtension',
'cookiecutter.extensions.UUIDExtension',
]
extensions = default_extensions + self._read_extensions(context)
try:
super().__init__(extensions=extensions, **kwargs) # type: ignore[call-arg]
except ImportError as err:
raise UnknownExtension(f'Unable to load extension: {err}') from err
def _read_extensions(self, context: dict[str, Any]) -> list[str]:
"""Return list of extensions as str to be passed on to the Jinja2 env.
If context does not contain the relevant info, return an empty
list instead.
"""
try:
extensions = context['cookiecutter']['_extensions']
except KeyError:
return []
else:
return [str(ext) for ext in extensions]
[docs]
class StrictEnvironment(ExtensionLoaderMixin, Environment):
"""Create strict Jinja2 environment.
Jinja2 environment will raise error on undefined variable in template-
rendering context.
"""
def __init__(self, **kwargs: Any) -> None:
"""Set the standard Cookiecutter StrictEnvironment.
Also loading extensions defined in cookiecutter.json's _extensions key.
"""
super().__init__(undefined=StrictUndefined, **kwargs)