Async Techniques and Examples in Python Transcripts
Chapter: asyncio-based web frameworks
Lecture: Concept: Flask to Quart
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0:00
Let's review converting from Flask to Quart and going from a synchronous view or controller function into an asynchronous one.
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So, if you're not entirely familiar with Flask the way it works is we have these apps. This is a Flask app that we allocate
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and then we apply this decorator to set a route and it's just a URL and the data that gets passed on the URL, things like that.
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Of course, you can see we have a regular def sun a regular function so there's no asynchronous happening here.
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We're going to implement our viewer controller method put the logic here, and in this case we're using some other services.
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We don't want to just cram all that into one place we want to be able to reuse the ability to say convert a ZIP code and country into a lat and long.
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If we put those into their own services these themselves are also synchronous and what we get back is a dictionary
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called sun_data, and in order to show that to the API consumer as json we have to call flask.jsonify and boom we've received a web request
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we've interacted with some external services converted that into a dictionary that is converted to json and that is the heart of an API.
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And this is how you do it in Flask. With that in mind, how do we do it in Quart? Well, it's very, very similar.
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Again, we have the app.route, but remember the app here comes from a Quart app being created, not a Flask app. Then we add an async decorator
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or async keyword, rather, for this method. So we have an async def sun and that allows us to use the await keyword.
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Then, we take that same logic that we've hopefully upgraded to async capable by making get lat long and for today both async methods themselves.
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And then we can await those results and this is the key to the performance that Quart is going to unlock. While we're waiting on get_lat_long
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while we're waiting on for today instead of just going, well, we're busy so just process and request, don't bother us
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can't do more right now, we're all blocked up. Most of the time, what does this method do but wait on those two services and adapt, you know
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convert time zones a little bit? Not much, so this is really all our website does is wait on these services.
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And so why don't we make that waiting productive? Do the await here and allow other async methods to run while we're awaiting these.
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And that's exactly what we're doing with Quart and finally we call it quart.jsonify and quart.abort so I'm to return our data that we got back.
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Once the dictionary converted to json, boom now you have a more scalable API with very little effort to make that conversion.