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We've got our data layer put together which means we can now go back over to our new rabbit handler

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the one we were working on just a little bit ago and start to put this implementation together.

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So inside of my new root handler at the very top I'm going to import those two models that we just created.

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So I'm going to get tickets from up one directory models ticket and order from up one directory at models

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order.

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Now we've got the ability to potentially fetch a ticket out of our database and potentially save a order

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as well.

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So now let's go down to our right handler.

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The first thing we're going to do inside of here is write out a couple of comments and really think

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about what logic we need to implement inside of here.

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So this is really going to require us to deeply understand what this application is all about.

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So as a quick reminder the whole idea here is that we want to build to create an order associate with

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a ticket that has already been created inside the database.

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And we also want to make sure that order will expire after 15 minutes.

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So we make sure need to make sure we set that expires at flag as well.

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So this mind let's write out a couple of different comments just to guide ourselves.

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The first step to do inside of here is find the ticket.

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The user is trying to order in the database so when we try to find the ticket that the user trying to

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order.

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If we fail to find it for some reason then potentially the ticket has already been purchased maybe the

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ticket has been deleted.

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Maybe the user for some reason crafted a malicious request to try to buy a ticket that doesn't exist

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for some crazy reason.

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So if we fail to find the ticket that the user is trying to purchase we're going to want to definitely

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return some kind of air immediately after that.

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We need to make sure that this ticket is not already reserved so the entire idea here with reserving

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a ticket for 15 minutes is that we're kind of planning around the idea of our application getting a

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lot of traffic and a lot of people trying to buy the same tickets at the same point in time.

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So in just one second of time in other words in the instant of time we can kind of imagine that we might

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get 10 different requests of a bunch of users all trying to reserve the exact same ticket so we need

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to somehow make sure that this ticket is not already been reserved by someone else.

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Just finding that ticket inside the database is not enough.

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Once we have done these two steps right here we're then going to calculate an expiration date for this

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order so as I mentioned we're going to assume that the order has 15 minutes to pay.

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After that the ticket will essentially go unlocked and the order will enter a canceled state that 15

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minutes is entirely arbitrary of course we can make it 15 seconds we can make it 15 days.

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It really doesn't matter.

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We're going to make it very easy to change variable but we do have to make sure that something time

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we calculate when that expiration date occurs.

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So we're gonna do that inside of here.

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Then after that assuming we get past all these checks we calculate that expiration date then we will

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finally go ahead and build the order and save it to the database and then immediately after that we

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definitely are going to want to tell the rest of our application that an order has just been created.

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We definitely need to think through what other services need to know.

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That order has been created.

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So what do a little bit of research or thinking on that front but chance all right now we can definitely

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assume that.

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Well we need to tell the rest of our application that order was created.

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We'll say publish an event saying that an order was created and remember publishing and events or creating

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a new event.

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We don't have any infrastructure right now to say that a order was created.

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The only kind of events we have are list out inside of our common module specifically inside of that

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events directory.

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So right now the only two events we have our ticket created and to get updated.

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So for this last step right here we will definitely once again have to go back over to our common module

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and create these new types of events something and say hey the order was created and then after we create

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that event of course we'll also have to define a publisher inside of our orders project.

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So there really is a lot of stuff going on inside of here.

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Let's get started right away.

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So we're going to go through this first step right here.

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We're going to try to find the ticket that the user is trying to order inside of our database on a line

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right above it.

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I'm going to take a look at the incoming request body and I'm going to pull off the I.D. the ticket

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that the user is trying to order.

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So I'll do a ticket I.D. I mean from wrecked up body

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so let's go ahead and then try to find that ticket inside the database.

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This is going to be a very standard Mongo DV or Mongoose query.

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So do a ticket is a weight ticket find by I.D. and we'll pass in the I.D..

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So now when we do this find my I.D. We're going to either get our ticket or not a ticket.

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So this might possibly be a value of null if we were not able to find an I.D. with the one that the

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user just provided.

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So we need to make sure that we handled a case in which no ticket was found.

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So say if there is not a ticket then let's throw a new not found error.

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Remember this is one of those custom errors we put together if we throw this air then our area handling

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middleware it will automatically capture it turn a response into a for a four and send it back to the

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user we do need to make sure that we import that type into our file however.

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Let's go back up to the top very quickly find our common module and import not found error.

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Now I don't want this video to run too long as well as we normally do.

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So let's now take a pause right here.

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We'll come back and start to implement everything else inside here in just a moment.