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Welcome back everyone in this lecture.

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We're going to expand on what we just showed and build out a basic crud API application basically being

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able to create read or daily items.

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And in this case we're just going to keep items in a list inside our Python script later on we're actually

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going to build out a full database and show you how to connect the flask Web site database to a rest

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application.

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But let's learn a couple of more functions or really methods inside of those resource calls.

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That's up over to the editor.

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All right.

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Here we are back at this the PI file.

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I went ahead and cleared everything just so we can get a little more practice setting everything up

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again.

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Basically for a start again from the top we'll say from flask import flask and then we'll say from flask

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restful import and we'll import resource as well as API.

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And let me collapse Left-Hand time.

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We're just dealing with one file.

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We create our application as always passing in the name variable.

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It's built in.

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And then we wrap that into the API call and then set that equal to the variable API.

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Notice the capitalization there.

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So we're going to do is we're basically going to have a list of puppies and each puppy is going to have

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a name sort to say puppies is equal to an empty list.

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And we're going to use the rest API in order to get a puppy name or Dilley a puppy name or post new

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puppy names as well.

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So we're going to create a class here called Puppy names and that's going to inherit from resource and

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then the main methods we're going to say here is def get.

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And then also have the post.

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And right now we'll just say pass for all of these so we don't get any errors here.

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There is a colon.

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So we have get and post and then we'll also do delete.

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So Def delete pass and then start filling these out.

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So we want to be able to do here is using the rest API we'll do our calls from postman.

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I want to be able to get a specific puppie given the name of a puppy.

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So what I'm imagining here is that puppies is going to be a list and inside a single puppy will have

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the following format.

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It's going to be a dictionary with the key name and the name of the puppy for example.

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Rufus So we're going to have each puppy have this format.

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So our list of puppies is then going to look something like this.

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Get a copy and paste from the notes here for a second.

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But basically we have a dictionary here named Rufus.

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Then the next one named Franki and so on.

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So that's what this list looks like.

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The list of dictionaries.

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So we have puppies.

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So if we actually want to get a puppy you need to cycle through the puppies list.

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So before we do get let's actually show how we would post a new puppy.

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So all these methods should have self and something that's important to know is when you're building

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out your API the get methods post methods methods they all need to take in the same parameters as arguments.

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So in this case if we want to get a puppy by its name then we need to make sure that the rest these

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also have the exact same parameters.

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So let's start with post since that will allow us to post a new puppy to this list the puppies that

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will show you how to get a puppy and they will show you how to delete a puppy.

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And then we will actually create a new class to just get all the puppies.

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But start of actually posting a new puppy.

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So how do we actually add something to that list.

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Well first to say pup is equal to name and then name what's going to happen here is our resource is

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going to take in a name through an API call and we'll clarify that in a second through the euro.

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But basically we're going to pass in a Yoro for a name and then we're going to create a dictionary that

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looks like this name and the name that was passed then.

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Then we'll take that pup and we'll say puppies penned that particular pup that is going to return pup.

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So you can think of this as we're essentially treating puppies here as an in memory database which is

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really just a list.

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So when we post the new puppy based off name we create an instance of a dictionary called name with

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that particular puppy's names who would pass and something like post Rufus.

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Then we get the dictionary we append that dictionary to that list of puppies and then we return that

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pup basically to tell us Hey this was the actual dictionary passed then and then we can later on get

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it.

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So imagine that we just posted a new puppy.

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Let's go ahead and get a puppy.

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So hard to make that happen when you say for every pup in that list of puppies.

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Well say if pup pups name because remember pup here is a dictionary in the sort of format.

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So if we want to get a particular name of the puppy we'll go through every dictionary in puppies and

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say if that pup name is equal to the name provided.

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So for example maybe we're searching for Rufus.

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So I'll say it's up to good dictionaries value for the key name happens to be equal to Rufus them or

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turn the pup.

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However what if we actually try to request a puppy that isn't actually in the puppies list yet.

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Well in that case when you go through an entire for a loop this will never be true meaning you'll never

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return anything.

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So after the for loop has been run I'm going to add in one more return statement and this return statement

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only executes if this for loop never has a hit with the same puppy name.

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So they will say return name and we'll say none essentially indicating that hey it was empty.

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Now we're going to add a little more to this later on but just keep that in mind.

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So all we're doing here is we want to post the new puppy we create this dictionary.

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A pen that pup puppies and then returned pup.

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If you want to get a puppy.

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We go through every pup in that list of puppies.

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So then we have these dictionaries.

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Each pup has a dictionary.

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We check that tickler dictionaries name value.

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So that would be something that would be like Rufus or Frankie or whatever happened to call dog.

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You check that same name that was requested and if so you return that pup which you're going to look

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like adjacent object essentially a python dictionary.

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If you go through the tire for a loop never find the match then return.

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Name.

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Finally let's show you how to delete a puppy.

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So for this it's going to work really similar.

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It will do the following we'll say for index position and pup in enumerates puppies so remember enumerate.

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Basically pass along a counter sordidness say Little did a tuple and packing here this will be a counter

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like 0 1 2 3 4.

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Pup is going to be the actual dictionary.

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So say for index position come up any numeric puppies if pup name is equal to name.

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So we have an actual match then we're going to do is say deleted pup

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is equal to puppies that pop at the index essentially since we're dealing for less we're just going

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to pop at that particular index or there happened to be a match and then if that happens we're just

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going to return note

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delete success.

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OK so all we're doing here for Dilley is someone is going to pass on the name of the puppy.

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We're going to go through the entire list of puppies and see if we find the matching name.

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They're going to pop that puppy and then we're going to send the note that hey the delete all successful

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if you want you could have also return more information like the actual deleted pup.

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In fact you don't really need to save this you could just do this command if you want it to but maybe

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later on you want to have a little print message here like print deleted pup just so you can keep track

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of things.

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It's really up to you.

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So we're going to save that.

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And those are the three basic methods that we can play around with right now since we're just dealing

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with a python list.

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So again we can post the new puppy we can't get a single puppy and we can Dilly a puppy.

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Now what I want to do is create one more resource in case you want to get a list of all the puppies.

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So say class all names resource.

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And this is going to have its own get call and we're going to say return and we can't just return puppies

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because that's a list.

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So what we want to do is return it in a Jaison type form.

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So we'll say puppies Colan puppies so knows this is going to be a dictionary of puppies and it is going

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to be a list of more dictionaries.

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So it's going to be kind of a nested J song structure.

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All right.

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And then what we need to do is we need to register these resources essentially add resources to the

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API.

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So we're going to say API dot add resource and then we'll start with the puppy names class that we created.

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And this is where we get to choose your l.

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You can actually connect to.

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So if I just head forward slash don't connect directly home.

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But again we probably want to have something that works if these actual methods.

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So notice all these methods take in a name as a parameter so you can think of this very akin to when

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we said app route we're essentially saying API add resource.

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And so then we're going to put in the your L or or someone should connect to this particular API call.

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So I'll say puppie and then we'll make sure it's a string.

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We've shown this before in the course and then we'll passen name.

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So essentially what this means is someone is going to be able to programmatically reach the home your

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elves for Slash puppie forward slash the name of a puppy and that connects to puppy names which then

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you can call either delete method or a post method or get method and we'll be playing around with that

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and just a little bit.

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Then I also want to add and this all names resource so I'll say API add resource.

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All names and this one will have it go to a different you or I will have this one go to puppies.

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Then once that's all done we'll say if name is equal to mean go ahead and run our app and we'll say

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that debug is equal to true.

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All right.

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So that's what we have so far.

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Let me zoom out just so we can get an idea of everything we just made same as before we set up our flask

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application.

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Connect that to an API.

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Right now we're just storing everything in a Python list keeping things simple.

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And we created our class puppy names and because it's a list we're just going to able to do a get a

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post and delete for the posts we create this little new dictionary based off what was provided at this

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url.

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We added it as a resource then we append that particular dictionary to the list and then we return it

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just so it's a confirmation that yes we did post this then if we want to grab a particular puppie based

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on name we go through every dictionary in the puppies list and if we get a match we would turn that

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puppy.

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Or else if we went through a for loop and then didn't get a match we say name was done.

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Then if we wanted to see a puppy really similar process to getting a puppy except we're also keeping

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track of the index so that we can pop that puppy out of that list.

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Then we have class for all names.

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And so same thing as a resource except the what it's going to return is just the entire list of puppies.

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OK then we added those resources and then we're good to go.

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So let's actually run this will say Python.

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I'm calling the simple API that pi will go ahead and run that.

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And then let's bring up postman.

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So now I have postman first thing I'm going to do is I'm going to try to get a puppy that does not exist.

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So say our home your L forward slash puppy forward slash and then you can type in any name here because

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technically there are no puppies that exist in the list right now.

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So let's go ahead and hit send and see what we get back.

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So you notice we get back.

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Name no.

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So essentially what happened is we returned back an empty dictionary and now we're receiving that as

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Jason.

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So the python nun gets returned as a note of Jaison.

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So that makes sense we just asked for a puppy that's not there let's try posting some puppies.

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So say post and now I make such a keep in the you are all the same but saying Hey post Sammy to that

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list the puppies so we'll send it and then it sends the request over and now I see name Sammy.

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So that looks like it worked.

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Let's go ahead and add Frankie.

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So these are my two dogs are going to add them to that list of puppies.

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So we're going to send that as well.

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Now I see named Frankie.

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And let's add one more.

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Let's go ahead and Cindy has a puppy name.

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We'll send that.

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And now I see named Cindy.

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OK.

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So now we have three puppies.

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Let's go ahead and try to get one of them.

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Let's make sure that this is all working on the say puppy Max.

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That puppy isn't something we posted.

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So if I send I get back.

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My name is nals.

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That makes sense.

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Now let's try one that we did actually put in which was Frankie.

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And if I send that now we actually get back name Frankie.

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So it looks like that's working.

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Finally let's try getting all the puppies.

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So you say gets in a of puppy for Slash name.

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We're going to say get puppies.

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So remember that was the all names class that was connected to four slush puppies.

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So going to send this and noticed when I get back I get back puppies and then a list of these Jason

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objects Sammy Frankie and Cindy let's tried deleting Sindy using our delete method.

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So say delete forward slash puppie forward slash Cindy.

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We're going to send this and notice it says delete success.

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So now let's try to get all the puppies again and see what we get back.

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So I'll say get puppies send this.

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And now I only see Sammie and.

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Since we removed Sindhi from that list of puppies.

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So it looks like everything's working and hopefully you can tell that the actual method calls are pretty

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straightforward.

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You just put in the method call make sure it matches and flask restfully is taking care of everything

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else on the back and for us something I want to know is.

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Let's imagine if we tried to grab a puppy that again isn't in our actual database so we're going to

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say a totally new name of puppy.

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Let's go ahead and say Davy isn't there a puppy.

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We're going to try to get Davy and noticed we get back named Noel.

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But take a look over here where it says status.

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So status 200 OK is the standard response for a successful request.

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What we can do is instead of just passing in or passing back Jason.

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When you actually don't have a puppy we can also use tuples to pass out a status.

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So let's go back to our code.

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So when I come back to our code and we said here return name none are going to come back to this and

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I'm going to say comma also for 0 4.

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Let me save that.

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And notice this is now updated again and then I'm going to again request puppy Davey.

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Remember Davy is not actually in the database.

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And when I send my request to get Davey I get back again.

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Name No.

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But now look this is changed to say four or four not found so that how you can actually send back HTP

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statuses as well because in this case you probably want to send that a 4 or four so the program knows

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hey you're asking for something that doesn't exist.

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Keep in mind because we're storing puppies as an in-memory list every time you restart your python script

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is essentially going to wipe clean that puppy's list.

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So keep that in mind if you keep restarting the lists because if you had a typo or something you may

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accidently request Papy that you thought was there but then got wiped clean when you restarted the python

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script.

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All right.

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That's the very basics of getting things posting things and deleting things.

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You should note however that pretty much anyone was allowed to get post and delete items from that list

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in the next lecture.

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We're going to discuss authentication which means we're going to need a special key in order to actually

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access this rest API which is always good practice in a more realistic situation.

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So we're going to cover that in the very next lecture.

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We'll see if.