How to await a coroutine in pdb

Question

I'm using an async library (asyncpg) and I want to debug some async calls to query the database.

I place a pdb breakpoint and want try out a few queries:

(pdb) await asyncpg.fetch("select * from foo;") *** SyntaxError: 'await' outside function 

It would be great to be able to do this because it would allow me to try out a few SQL queries and see the result, all from the comfort of my debugger.

Is it possible?

Answer 1

I had a similar problem debugging the useage of aiofile. I then found a solution using nest_asyncio. For example if one has the following async example script:

import asyncio from aiofile import async_open import nest_asyncio   async def main():     async with async_open("/tmp/hello.txt", 'w+') as afp:         await afp.write("Hello ")         await afp.write("world")         afp.seek(0)         breakpoint()         print(await afp.read())   if __name__=="__main__":     loop = asyncio.get_event_loop()     nest_asyncio.apply(loop)     loop.run_until_complete(main()) 

One can then do:

-> print(await afp.read()) (Pdb) loop = asyncio.get_event_loop() (Pdb) loop.run_until_complete(afp.read()) 'Hello world' (Pdb)  

Admittedly it is a bit more tedious then await asyncpg.fetch("select * from foo;") or await afp.read() but it gets the job done. Hopefully a more elegant solution will come up in the future.