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import typing as t
from jinja2 import BaseLoader
from jinja2 import Environment as BaseEnvironment
from jinja2 import Template
from jinja2 import TemplateNotFound
from .globals import _app_ctx_stack
from .globals import _request_ctx_stack
from .signals import before_render_template
from .signals import template_rendered
if t.TYPE_CHECKING:
from .app import Flask
from .scaffold import Scaffold
def _default_template_ctx_processor() -> t.Dict[str, t.Any]:
"""Default template context processor. Injects `request`,
`session` and `g`.
"""
reqctx = _request_ctx_stack.top
appctx = _app_ctx_stack.top
rv = {}
if appctx is not None:
rv["g"] = appctx.g
if reqctx is not None:
rv["request"] = reqctx.request
rv["session"] = reqctx.session
return rv
class Environment(BaseEnvironment):
"""Works like a regular Jinja2 environment but has some additional
knowledge of how Flask's blueprint works so that it can prepend the
name of the blueprint to referenced templates if necessary.
"""
def __init__(self, app: "Flask", **options: t.Any) -> None:
if "loader" not in options:
options["loader"] = app.create_global_jinja_loader()
BaseEnvironment.__init__(self, **options)
self.app = app
class DispatchingJinjaLoader(BaseLoader):
"""A loader that looks for templates in the application and all
the blueprint folders.
"""
def __init__(self, app: "Flask") -> None:
self.app = app
def get_source( # type: ignore
self, environment: Environment, template: str
) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable]]:
if self.app.config["EXPLAIN_TEMPLATE_LOADING"]:
return self._get_source_explained(environment, template)
return self._get_source_fast(environment, template)
def _get_source_explained(
self, environment: Environment, template: str
) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable]]:
attempts = []
rv: t.Optional[t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]]
trv: t.Optional[
t.Tuple[str, t.Optional[str], t.Optional[t.Callable[[], bool]]]
] = None
for srcobj, loader in self._iter_loaders(template):
try:
rv = loader.get_source(environment, template)
if trv is None:
trv = rv
except TemplateNotFound:
rv = None
attempts.append((loader, srcobj, rv))
from .debughelpers import explain_template_loading_attempts
explain_template_loading_attempts(self.app, template, attempts)
if trv is not None:
return trv
raise TemplateNotFound(template)
def _get_source_fast(
self, environment: Environment, template: str
) -> t.Tuple[str, t.Optional[str], t.Optional[t.Callable]]:
for _srcobj, loader in self._iter_loaders(template):
try:
return loader.get_source(environment, template)
except TemplateNotFound:
continue
raise TemplateNotFound(template)
def _iter_loaders(
self, template: str
) -> t.Generator[t.Tuple["Scaffold", BaseLoader], None, None]:
loader = self.app.jinja_loader
if loader is not None:
yield self.app, loader
for blueprint in self.app.iter_blueprints():
loader = blueprint.jinja_loader
if loader is not None:
yield blueprint, loader
def list_templates(self) -> t.List[str]:
result = set()
loader = self.app.jinja_loader
if loader is not None:
result.update(loader.list_templates())
for blueprint in self.app.iter_blueprints():
loader = blueprint.jinja_loader
if loader is not None:
for template in loader.list_templates():
result.add(template)
return list(result)
def _render(template: Template, context: dict, app: "Flask") -> str:
"""Renders the template and fires the signal"""
before_render_template.send(app, template=template, context=context)
rv = template.render(context)
template_rendered.send(app, template=template, context=context)
return rv
def render_template(
template_name_or_list: t.Union[str, Template, t.List[t.Union[str, Template]]],
**context: t.Any
) -> str:
"""Renders a template from the template folder with the given
context.
:param template_name_or_list: the name of the template to be
rendered, or an iterable with template names
the first one existing will be rendered
:param context: the variables that should be available in the
context of the template.
"""
ctx = _app_ctx_stack.top
if ctx is None:
raise RuntimeError(
"This function can only be used when an application context is active."
)
ctx.app.update_template_context(context)
return _render(
ctx.app.jinja_env.get_or_select_template(template_name_or_list),
context,
ctx.app,
)
def render_template_string(source: str, **context: t.Any) -> str:
"""Renders a template from the given template source string
with the given context. Template variables will be autoescaped.
:param source: the source code of the template to be
rendered
:param context: the variables that should be available in the
context of the template.
"""
ctx = _app_ctx_stack.top
if ctx is None:
raise RuntimeError(
"This function can only be used when an application context is active."
)
ctx.app.update_template_context(context)
return _render(ctx.app.jinja_env.from_string(source), context, ctx.app)
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