Proposal: Adding pg_engine flag

[hzlmn]

Would be nice if tool provide ability to choose postgres engine (aiopg or asyncpg). Possible command could looks like

create-aio-app project --pg_engine asyncpg

If you consider it as an option i could send pr.

[aio-libs-bot]

GitMate.io thinks possibly related issues are https://github.com/aio-libs/create-aio-app/issues/24 (add wait script for redis), https://github.com/aio-libs/create-aio-app/issues/1 (Add flake8 and travisci builds), https://github.com/aio-libs/create-aio-app/issues/8 (Add test for the cookiecutter template), and https://github.com/aio-libs/create-aio-app/issues/21 (Add Procfile for deploying to Heroku).

[Arfey]

I think it's good idea. I will wait for your pr 😀

[hzlmn]

There is current limitation in cookiecutter to add conditional options like if we check use_postgres only then we should choose postgres_engine option. So maybe it will be easier to combine this too options into one.