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- [Instructor] Hi and
welcome back to the course.

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In this video,

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we're going to be creating
our store resource.

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Now, the first thing to do

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is to go over the resources folder

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and create a new file which
I'm gonna call store.py.

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Now, there are two ways
that we could go about this.

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We could start everything from scratch

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and create each of the endpoints

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or we could copy and paste,

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and then change the item endpoints.

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For your benefit, I'm gonna go

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for creating everything from scratch.

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However, you can speed along,

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maybe change the video speed

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to one times five, if you prefer,

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just to go through things a bit faster

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since you're already familiar
with how all of these goes.

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The first thing to do is to import

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the things that we need
from the libraries.

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So, from flask_restful,

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we're gonna import Resource.

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And from the store model,

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we're gonna import that.

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So, from models.store import StoreModel.

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Then we're gonna create our
first resource, the Store,

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which is going to extend
the Resource class.

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And in Python, remember the way we extend

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is by putting between brackets

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directly after the class name.

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So what endpoints do we need for a store?

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A store only has a name,

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so I'm only gonna create get,
post, and delete endpoints.

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I'm not going to create a put endpoint

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because changing a store name

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inherently changes everything
about the store, I guess,

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so I'm not gonna allow editing of stores.

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So I'm gonna create a
get which takes in a name

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and I'm gonna put pass.

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That means do nothing,

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just to create the structure
of what we're making first

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and then we'll go implementing each one.

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So the post

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and the delete.

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So these are the three things
that we're gonna implement

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and down here, we're also gonna implement

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a StoreList(Resource).

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And we're gonna do that later on.

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The get method, what this has to do

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is return a specific store.

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So as we know, we can get a store by name

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using the StoreModel, so
StoreModel.find_by_name

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and that may return a store object

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or it may return none.

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So if the store was returned,

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then return store.json.

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Remember, that's also going
to return the items as well.

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And if we didn't return store.json,

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that means that the store was not found,

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so we can return a message
saying, "Store not found,"

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followed by a 404.

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Remember, what we're
returning here is a tuple,

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a tuple of dictionary
first and code after.

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And Flask-SQLAlchemy, as
well as Flask, see this,

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and say, "Okay, you wanna
return this in the body

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"and this in the status code."

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The default is 200, which is
what we're returning there,

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so we don't have to put it in.

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That's our get method.

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All that it does is it
looks in the database

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to see if it's there

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and then returns it if it is there

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or returns a store not found otherwise.

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The post is going to be fairly similar.

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The first thing we're gonna do

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is look to see if the
store already exists.

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So if the StoreModel.find_by_name

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already exists, then that means

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that we don't wanna create a new one

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because it's already there,

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so we're gonna return a message

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saying that the store is already there.

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Like that, and here, we're
gonna use the format method

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which you can do on any string.

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And what that does is that replaces

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this opening and closing curly
brace by the value there.

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And then we're gonna return
400 as the status code.

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Now, if that didn't happen,

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that means the store doesn't exist,

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so we can create a new one

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with a given name that is
passed in as an argument.

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And then we're going to
try to save the store

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to the database

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and if that fails, we're
going to return a wee message

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and you have to spell things
correctly, not like I do.

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And the code that we're
returning here is 500

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because we are not sure
exactly what the error was.

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Likely, it's some sort
of database problem,

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so it's not the user's
fault, so we'll return 500,

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which means internal server error.

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It's our fault.

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Now, if that didn't get returned,

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that means that we succeeded

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at saving to database, so
we can return store.json

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and 201, saying that it has been created.

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Finally, the delete method here

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is going to once again look
to see if the store exists

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and if it does, we're going to delete it.

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And if it doesn't, we're
not gonna do anything.

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So really, we're just gonna
say that it was deleted.

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And if the store doesn't exist,

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the end scenario is the same,

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the store doesn't exist.

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So the delete method, really
what the delete method causes,

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is for the store to stop existing.

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If the store didn't exist to begin with,

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the user doesn't really care.

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It doesn't care that the
store wasn't there already.

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It only cares that it has been deleted.

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It's no longer there.

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And the StoreList as
well, for good measure,

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is going to be very
similar to the item list.

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All that is gonna return
is a dictionary of stores

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where the stores each
have to be their own JSON.

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So go ahead and implement this yourselves,

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if you know how to do this,

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or look at the item list resource

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if you need some more guidance.

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Hopefully you got that.

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There are two ways to do it.

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Once again, one is to do store.json

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for store in StoreModel.query.all

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or you can use the list and the map

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as we have seen in the
past, if you prefer.

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That's everything for our resources.

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Now we've got our two resources.

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And as you can see, now that
we know what we're doing,

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it's fairly quick to
implement these resources

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because we know exactly what
each endpoint is meant to do.

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Now we're gonna go over to the app

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and we're going to import the
resource from resources.store

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import Store and StoreList.

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And then we're going to make sure

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to add the resources to the API,

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so api.add_resource,

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Store, and the endpoint for our Store

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is gonna be store and the name.

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And on the bottom,

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we're gonna add also api.add_resource,

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StoreList, and that's gonna be /stores.

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Something important to remember

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is that SQLAlchemy
creates the tables for you

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and so we have to delete
data.db there, so it does that,

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but also it only creates
the tables that it sees.

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Now that's important

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because it goes through imports.

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So here, for example,
we're importing Store

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and then that goes over to the StoreModel

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and the model, sorry, the Store(Resource),

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and the Store(Resource)
imports the StoreModel.

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And the StoreModel has the table
and the column definitions.

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So as you can see, there is a way for us

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to have imported the StoreModel.

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If we don't import Store,

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the table for stores won't get created.

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Well, if we don't import
really any of this.

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The table for stores won't get created

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because SQLAlchemy will not be able to see

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that that is a thing
that exists in our app.

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So it's important that
you import the things

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that you want SQLAlchemy
to be able to know about.

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And in some cases, if
you don't have a resource

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associated with something

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that you wanna store in a database,

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you can just import a model directly

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and then SQLAlchemy
will see that it exists.

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So that's everything for this video.

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In the next one, we're going to be looking

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at testing this entire thing

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and so, yeah.

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As you can see, it's really easy

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to add new models and
relationships between them

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and that's part of the power
that SQLAlchemy gives us.

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So that's everything for this video

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and I'll see you on the next one.