Building data-driven web apps with Flask and SQLAlchemy Transcripts
Chapter: MongoDB edition
Lecture: Package details cleanup
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0:00
We've cleaned up the homepage.
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Now let's just click on one of these
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and see how amazing this is.
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Oh, darn it, not so amazing.
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Remember we had the relationship
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from release over to package.
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Well now we're running into the issue
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but in the other direction.
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We will go into a package and asking for its releases.
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So we just need to change a little bit how this works
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in order to match with our new data model.
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So what we need to do is let's close these off
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and it turns out that the error is actually right here.
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We can go show you that
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if we just scroll down and click right there.
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It's this, it says, hey, we don't given a package
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it doesn't have our releases.
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Well, what are we really trying to do here?
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We're trying to go to this and say
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well, if there's a package, go get me its latest release
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so we can set the latest release in the latest version text.
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So let's just change how this works.
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Let's say self.latest_release = package_service.
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get_latest_release_for_package(self.package.id)
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Like so.
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Now, this function doesn't exist yet
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but we're going to write in a second.
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Now, let's just fix this up really quick here.
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So the goal over here was to say, go to the
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and get us the latest release that's already done
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and then it's here's to say what is the text
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for that latest one.
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We probably want to add one more check
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if there is actually a latest release, okay.
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If we make this change and we write this function
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this page, this package details page
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should be back in action.
1:27
So let's go write this.
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It's going to be package_id, which is a string.
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What's going to give it?
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What are we getting back?
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We're getting an optional of release. Okay.
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We want to do a query on releases, super easy.
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We go to release, we say objects
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and we don't need to use filter here.
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We can just put it right inside of object
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and say package_id equals package_id
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that we're passing in and we want to do an order by.
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What do you want to order by?
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Let's go over here. created_date.
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We want the latest one, remember?
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So we say, - that and then here we say .first.
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Give us one or None and that's it.
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That will fix this or go to the database, do a query
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get us the latest release for our package.
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And here you can see we have an index on created_date
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and the thing we're sorted on as well as the package_id.
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So this should be really, really fast.
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All right, let's go and see how this works.
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Try again. No, what have we missed?
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Oh we still are doing this test
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even though it doesn't make sense anymore.
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Try again. Tada, there we go.
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Our site is fully back in action
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and we can come down here and see all the details
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here you can see we got our latest release for that one
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on 2018 in May 30th. Super.
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So we've now done a little tiny cleanup that we had to do
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based on the change in the structure and the data model
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and now our app is back and working and that's it.
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We've converted this app over to MongoDB.
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I've done a lot of talking and not that much typing.
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If I just went and heads down
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and started converting and converting
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you can see this would go pretty quick.
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We did come with the MongoDB data model already done
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so I don't know. What do you think?
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An hour, two hours to do this conversion.
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That's not a ton of work and why is it not a ton of work?
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Because we were able to change just these couple of files
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'cause all of the data access was there
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and because we're using MongoEngine
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it was very similar in the way we wrote our queries
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and got objects back
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to the way that we work with sequel alchemy.
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Super cool on both counts.
