#100DaysOfCode in Python Transcripts
Chapter: Days 88-90: Home Inventory App
Lecture: Bug and functionality fixes
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So while the app actually does work
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there are quite a few things that we've left out.
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And I've done this on purpose because this is what I'd
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like you to work on for your Day 3.
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If not, just work on to expanded just for fun.
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You can do it after your 100 days is up,
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whatever you feel like.
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Or maybe you can use it as an idea
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to factor it into your own inventory app.
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This first thing is,
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is that we haven't actually captured incorrect input.
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We have here.
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So for example, if we're at the main menu
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we put the letter a.
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We just get invalid option, try again.
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Even if we do something like 11.
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We know it's a number but it doesn't
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match any of these, so we get invalid option try again.
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Now what happens if we add a room?
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Now we know we have kitchen in there.
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But if we add kitchen again, what happens?
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Kitchen already exists.
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So we need to be able to capture that.
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What happens if someone wants to add multiple bedrooms
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but they just want to call it bedroom.
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It's a silly scenario because can't think of anyone who'd
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do that but this is something that needs to be captured.
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Rather than allowing an error to just suddenly pop up
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and then exit out of the app.
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So there's one.
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Adding multiple rooms can cause a problem.
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So, see if you can figure out a way to capture that.
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Now that we have that,
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let's see if we can add duplicate items.
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So we'll add a knife for $20.
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Let's try and add another knife for $20.
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And that works.
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So why does that work?
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Well that actually works because SQLite has its own
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sort of tagging behind the scenes.
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It tags each entry with its own id.
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So you can have duplicates items below a table name.
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You can't have duplicate table names though.
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Now is that a problem?
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For me i don't think it is a problem.
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But if you wanted to capture that you could.
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That's something to capture.
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But what about this?
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Let's say we want to add a microwave,
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but by accident instead of hitting $20 we hit 2o.
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We've entered in a letter instead of a number.
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What's going to happen?
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It allowed it didn't it?
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So it allowed the fact that we had a letter and a
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number in there.
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Which is wrong,
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so if you actually pull up our
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SQLite database in SQLite viewer.
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Which I have done here.
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You can see we now have values
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but microwave is now accepted to O.
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So what we'll do now
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by allowing this to happen,
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we've probably caused problems here.
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So view inventory list, let's do kitchen.
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There we go, it failed because
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it needs it formatted as a number not a string.
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This is for the actual value calculation.
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So it was able to print it all out.
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Once it got to the actual calculation for the total value,
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didn't like it.
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Same thing for actually printing out
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microwave and its value.
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So that's something we screwed up and we'd actually,
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in that case we actually broken the application completely
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because we have no way in here to code a deletion.
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Which again is something you could do.
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So I'm going to go manually into the database here.
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And we'll delete this record
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because it's going to cause us problems.
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I'll demonstrate that again.
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This time we'll add an item to the inventory.
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We'll choose the room study.
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Study.
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And then let's add ourselves a chair.
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And instead of actually entering a number at all.
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Let's just use the word water.
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And you can see it actually returned
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and we were able to add it successfully to the table.
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So again, that's going to cause us issues
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and we'll have to delete it manually from the database.
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We can also capture different errors to do with launching
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the app as we saw.
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I've only got this sampler here but we can actually put
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some more scenarios in there if you wanted.
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That's something you could work on.
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And the last thing here is, check this out.
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We just entered an empty room.
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A room with name space has been added to the database.
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That's a problem, so.
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That's something we need to capture as well.
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This is all stuff you can work towards.
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If you get bored and if you want to work towards it.
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But you can see that this is all stuff,
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if you're creating an app that you have to take
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into account.
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And just one other thing as well that is rubbing me
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the wrong way.
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Is this elif tree here.
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I don't like that, I've done it
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just for demonstration purposes but essentially
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you would preferably throw all of these into a dictionary
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and make it a bit more Pythonic.
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There's no need for it to be this large.
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But either way, this is your little go to points to
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see if you can expand on this and improve it.
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If you wish.
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You might even just think about writing this app
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yourself in a way that you see fit.
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And covering these problems as you build it.
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So have fun.
