Modern APIs with FastAPI and Python Transcripts
Chapter: Building our first API
Lecture: Concept: Returning errors
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If you've received some input, some data from the user that you just can't process because it's not in the right format or something's missing,
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some of that is actually handled already by FastAPI. So for example, if X is passed over and the X is a string that can be converted to an integer,
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FastAPI will just handle that. It will return a JSON response with a dictionary that has some details about the error message.
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But there's other times where just certain values are required. Like, for example, you have to have a non-zero Z if Z is
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specified in this calculation because you'll get a divide by zero. So in this case, we got Z from the user, and it's zero, so we need to tell them "no,
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no, no, this is bad". If we just try to do the division, it's going to crash our server, they'll
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get a 500 response, still think our service is unreliable when really they sent us
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bad data, so we want to communicate that back. We're going to create some kind of
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error dictionary not shown here that we're gonna return like error is the message, you know, Z has to be non-zero for division and so on.
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We're going to do that as a FastAPI JSON response. We're going to set the status code to 400 or whatever status code you think is
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the best fit and then the content to a dictionary, which will be converted to JSON, and sent back along with the status code,
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and that's it. Super easy to return errors in this controlled way back to the clients.