fix #486, add Starlette support

[wwwjfy]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 1751

• 178 of 180 (98.89%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.01%) to 98.573%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
gino/ext/starlette.py	83	84	98.81%
tests/test_starlette.py	89	90	98.89%

Totals
Change from base Build 1732:	0.01%
Covered Lines:	4215
Relevant Lines:	4276

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💛 - Coveralls

[leosussan]

Thank you for taking this on Tony - this is awesome.

Testing this out with FastAPI (object inherits the Starlette model, so this should work for it). Runs very well locally - will troubleshoot a bit (doesn't yet fix my issue with Cloud Run, but that's an issue for another day & I'm pretty sure that has more to do with asyncpg than Gino).

It does require a bit of reorganization of my code (I define db in my models & import to main.py, which this isn't happy with unless route imports come below db definition) but this is not the end of the world.
Works really well after you do this!

[wwwjfy]

Glad to hear that.
I tried to implement a "pure" middleware for that, but there are a few preconditions making that a bit more complex, so I end up with the current one.

Let us know if you have other ideas how to organise it and make it more user friendly. :)

[fantix]

Please feel free to merge - I'm sorry I don't have time to review recently. Thanks a lot for the good work!