Asyncio support

[ugoi]

Is your feature request related to a problem? Please describe.

I'm trying to use DocxTemplate inside my async FastAPI endpoint but since it's blocking I have to make my FastAPI endpoint synchronous which will create additional thread. I don't want to use up all my threads when getting many requests.

Describe the solution you'd like

If I could simply await the DocxTemplate and all it's methods this would be no problem.

Describe alternatives you've considered

Maybe use aiofiles or something / not sure about this

Additional context

[waketzheng]

@ugoi fastapi depends on anyio, you can do it like this:

from io import BytesIO

import anyio
from docxtpl import DocxTemplate


async def main() -> None:
    doc = DocxTemplate("my_word_template.docx")
    context = {"company_name": "World company"}
    doc.render(context)
    bio = BytesIO()
    doc.save(bio)
    filename = "generated_doc.docx"
    content = bio.getvalue()
    size = await anyio.Path(filename).write_bytes(content)
    print(f"Write to {filename} with {size=}")


anyio.run(main)

To control the concurrency number:

import sys
from io import BytesIO

import anyio
from asynctor import timeit  #  pip install asynctor
from docxtpl import DocxTemplate

LIMIT = 5


async def new_docx(filepath: anyio.Path, limiter) -> None:
    doc = DocxTemplate("my_word_template.docx")
    context = {"company_name": "World company"}
    doc.render(context)
    bio = BytesIO()
    doc.save(bio)
    content = bio.getvalue()
    async with limiter:
        size = await filepath.write_bytes(content)
        await anyio.sleep(1)  # Sleep 1 second to verify the limiter result
    print(f"Write to {filepath.name} with {size=}")


@timeit
async def main() -> None:
    if sys.argv[1:] and sys.argv[1].isdigit():
        global LIMIT
        LIMIT = int(sys.argv[1])
        print(f"Changed LIMIT to {LIMIT}")
    filename = "generated_doc.docx"     
    async with anyio.create_task_group() as tg:
        f = anyio.Path(filename)
        limiter = anyio.CapacityLimiter(LIMIT)  # limiter must be defined outside the for loop
        for i in range(5):
            p = f.with_name(f.stem + f"_{i}" + f.suffix)
            tg.start_soon(new_docx, p, limiter)


anyio.run(main)