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

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In this video, we're just going
to improve the code slightly

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by making use of our User class.

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The changes are only gonna
be in the user.py file.

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Remember how we've got
a User class up here

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that gives us the ability
to find by username.

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What we're going to do in the post request

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of the user register is make
sure that we're not registering

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a user with the same username twice.

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Now, knowing that the
user.find_by_username method

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gives you a user object, or
it gives you none if that

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didn't exist, how would you
check that a user exists

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in this post method here?

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Give yourself a wee
minute to think about it.

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How might you check that a
user exists already or not?

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Think about it, try to
implement a solution,

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and then come back and we
will solve it here as well.

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Okay, hopefully you got that.

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What I'd recommend is to do

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if
User.find_by_username(data['username']).

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Remember, if something
means if that is not None.

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So, if this is not None, we're gonna do

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return {"message": "A user with that

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username already exists"}, 400.

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Okay, and remember, if
we return, we do not run

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any of this stuff here.

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Make sure to have this in front of

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the connection creation line.

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If we put this outside
creating a connection,

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that connection will never close

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because we will never run this.

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So, make sure to put
this at the very start

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after parsing the data through.

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Now we have our main User class

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with this find_by_username
and find_by_id methods,

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and we are using the
find_by_username to find a user

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or give us None.

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So, down here, if User.find_by_username

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with the data that is being passed in

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through the JSON request is not None,

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then that means a user with that username

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is already in the database
because we found one

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so we can return this message.

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You can go ahead and try this in Postman

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but, believe me, it works.

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This is exactly where you
would expect it to do.

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This does exactly what you expect it to do

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so we're not gonna go into
trying it in Postman as well

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just to save you some time.

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Thanks for joining me in this video,

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and I'll see you in the next one.