import contextlib
import sys
import trio
from collections.abc import AsyncGenerator
from jinja2 import Template, select_autoescape
class MyModel:
class objects:
@staticmethod
async def all() -> AsyncGenerator[str, None]:
while True:
yield "hello"
template = """
<html>
<head></head>
<body>
{% for m in model.objects.all() %}
{{ m }}
{% break %}
{% endfor %}
</body>
</html>
"""
async def amain() -> None:
async with contextlib.aclosing(
Template(
source=template, enable_async=True, extensions=["jinja2.ext.loopcontrols"]
).generate_async(model=MyModel)
) as agen:
async for v in agen:
print(v)
break
def main() -> int | None:
return trio.run(amain)
if __name__ == "__main__":
sys.exit(main())
results in:
<html>
<head></head>
<body>
/home/graingert/.virtualenvs/demo-jinja-asyncgens/lib/python3.12/site-packages/jinja2/environment.py:1371: ResourceWarning: Async generator '<<template>>.root' was garbage collected before it had been exhausted. Surround its use in 'async with aclosing(...):' to ensure that it gets cleaned up as soon as you're done using it.
yield event
ResourceWarning: Enable tracemalloc to get the object allocation traceback
running
results in: