#100DaysOfCode in Python Transcripts
Chapter: Days 25-27: Error handling
Lecture: Demo: try-except blocks
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We've seen that, calling this API, may raise errors.
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And notice the WiFi being off,
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pretty much anything we search for
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is going to result in an error.
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So, we're going to turn the WiFi back on.
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But before we do, let's convert this full on crash
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to something we can catch, maybe log,
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send a message to the user.
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Or we could try again, who knows?
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Here's how error handling in Python works.
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What we're going to do is,
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there's a couple options.
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We could treat this as a separate section.
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Let's say, this part that actually interacts
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with the data does the request.
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We're going to treat this as a block
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that should either work,
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or not work here.
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So, we can come up here and type the word try:
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And indent that into the block.
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Then if something might go wrong,
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we'll say, except:
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And I'll say, print
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Oh, that didn't work.
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And we'll just print that out.
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Yeah?
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Now Python says this is a little aggressive,
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it's too broad, but, that's okay.
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This is going to work for now,
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and then we'll refine this a little bit.
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So now if I run it,
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oh that didn't work.
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It's a big bad crash, um, we just say,
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"You know, that didn't work."
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We could've logged it.
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We could actually loop around and try again.
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All sorts of things.
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But at least we're giving proper feedback
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to system here.
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Let's turn this back on.
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WiFi's back.
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Let's try again.
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Let's search for capital again.
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Boom, it's working.
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Here's how the flow goes.
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We're going to run every function here.
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And if it succeeds, it's just going to run
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from here to there and then skip
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over this except block.
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But if at any step something goes wrong, like,
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suppose, say right here, this title doesn't exist,
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and it's going to be an error
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the first time through or something.
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It's going to immediately stop what it's doing
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and jump down here.
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If this throws an error,
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we're not even going to run this prank code.
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We're just going to jump straight from here
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to there to deal with it.
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So, we can try some stuff, didn't find anything.
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Eventually, we'll run into these random errors.
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That one didn't work. So, this is great, but what didn't work?
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Wouldn't it be nice to know what is going on?
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It turns out there's three or four categories of errors.
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One of which is the network is down.
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But there's actually others.
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So, we're going to adjust this
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to handle these particular errors.
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So, here's how we can stop the errors
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from crashing our program.
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But let's see how we can actually deal with the errors
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in a more fine grained way.
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One message for say, network errors.
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Another message for say,
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if you didn't input any keyword to search for.
