Python Jumpstart by Building 10 Apps Transcripts
Chapter: App 10: Movie Search App
Lecture: Introduction to the movie search app
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Application number 10, let's build a movie search app.
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Now it turns out we are going to put this movie search app
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into a particularly unreliable environment,
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so we are going to have to do a lot of work
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to make sure our movie search app is durable
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and it doesn't crash or behave too weirdly.
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Let's see how that's going to go.
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We are going to build an app that looks like this, standard header.
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We are going to enter some text and this text is going to be the title of a movie.
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So, here we might say Top Gun,
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and we'll try to go out to the internet and find information
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about movies with Top Gun in their title,
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but you can see in this case it said oh sorry,
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the network happens to be down so no searching right now.
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But our app doesn't crash or give weird errors it just says hey, the network is down,
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check your wi-fi or something like this.
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Then later we try again, search for Top Gun and boom,
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we get real live movie search results off the internet.
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So it might sound like this is about searching movies,
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but really what we are going to focus on is error handling,
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writing durable reliable applications.
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So we are going to focus on error handling,
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the primary way to do this in Python is with exceptions, and try/except blocks,
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you'll see that we can have
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multiple sort of error handling clauses in any particular situations,
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so there might be a host of reasons that our movie app doesn't work,
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maybe the DNS server is down, maybe we entered a bad title,
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maybe the wi-fi is down, maybe the other server actually gave a 500,
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maybe malformed data came back,
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so we can actually catch different errors and give different messages back.
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We might want to tell the users something different
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if the data that came back was malformed,
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rather than if the network was not connected.
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Right, so we'll use multiple what are called except blocks to do this
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and that will allow us to differentiate errors based on the type of the error,
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and ultimately, we are going to talk about writing reliable code
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and you also see how to raise errors and exceptions
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not just catch them because we are going to throw some
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to sort of make our app particularly unreliable.
