All language subtitles for 016 Creating and Mounting Multiple Routers_Downloadly.ir_en

In this lecture, things will start

to get a bit more advanced.

And that is because we'll now create multiple routers

and use a process called mounting.

So let's see how all that works.

Now, before doing any of that, let's keep in mind

that the ultimate goal will be to separate all the code

that we have in this file into multiple files.

So what I want, is to have one file

that only contains all of these routes

then I want to have another file,

which has the routes for the users.

I will also want to have a file which contains the handlers

only for the users and then also one file

that will contain all the handlers for the tours, okay?

And so that's actually what we're gonna do

in the next lecture.

But in order to be able to do that,

we actually need to now create one separate router

for each of our resources.

So, let's go back to our routes here and so right now,

we can say that all our routes, so these four routes here,

we can say that they're all kind of

on a same router, okay?

And the router, is this app object.

But if we want to separate these routes

into different files, so again,

one file for these two routes

and one file for these two routes,

then the best thing to do, is to create one router

for each of the resources, okay?

And so, this is how we're gonna do.

It's actually not that complicated,

but you will have to wrap your head

around a couple of concepts, okay?

So, let's start by saying,

const tourRouter is equal to express.Router.

Okay, so just like this,

we create a new router and save it into this variable.

Alright, and so now let's use that router

for these two routes.

So here we use it instead of app.

Alright, so now we have two router and then route

and then of course, the get and the post routes

on that router.

Now, how do we actually connect this new router

with our application?

Well, we'll use it as middleware, alright?

And so that is because, this new modular tool router here,

is actually a real middleware, alright?

And so we can say, (keyboard typing),

app.use, and then the route but let's keep that for later.

So we can use, the tourRouter on our application

and where do we want to use the tourRouter?

Well, we want to use it on,

/api/version one/tours, okay?

So again, this tourRouter here, is a real middleware.

And we want to use that middleware for this specific route.

Okay, and so we use app.use

and specify the middleware function, which is this router,

then we specify the the route so the URL,

for which, we actually want to use that middleware, okay?

And so just like this,

we created basically a sub application, okay?

Now, there's just one thing

that we really need to change here,

which is these routes in here, okay?

So let me change this here, and then explain

why it has to be this way.

So here, we only want the route,

and in here, we only want the id, okay?

Now, why is that?

Well, it's because this tourRouter middleware,

only runs on this route here anyway, okay?

And so once we are in the router,

then we already are at this route.

So at our tourRoute, and so this first route

that we had to before, we only want to run it as,

api/version one/tours

and so that is what this route here now means, okay?

So it's basically the route of this URL, okay?

So is this small mini application, alright?

So, actually, when we create a router system like this,

we actually say that we kind of create a small sub app

for each of these resources, okay?

So this is the route of or mini application,

which is again, at /tours, Okay?

And then the second route, is at /id, right?

And that's because, before,

it was at tours /id, so it was all of this.

So like this, but now, this URL here

is already in our kind of parent route up here, right?

So let's say that we have an incoming request now

for /api/version one /tours/version id.

So the request goes into the middleware stack

and when it hits this line of code here,

it will match this URL here, right?

So it will match this route and therefore

or two router middleware function will run.

So or two router is this sub application that we created,

which in turn has its own routes, okay?

And if the request was for /id, well,

then it will inside our mini app,

hit this route here, right?

And finally, of course,

it will run one of these handles here,

depending on the method that was used.

So I hope that made sense.

And so let's now actually go ahead and do the same

for all users, alright?

So, I will go ahead and create another router here,

(keyboard typing) called, the userRouter,

and then just like before, it's express.Router

not like that, yeah.

Okay, so use a router,

and then we need to do the same process as here.

And by the way, this is called mounting the router, okay?

So mounting a new router on a route, basically, okay?

So we have now users and here user.

And actually, mounting the routers,

has to come after all of these definitions

or at least after we declared a variable, right?

So we cannot use the routers

before we actually declare them.

Okay, now all we need to do is to go ahead

and also change the routes in here.

And so just like before, if there is now a request

for /api/version one/users/id,

the request will enter the middleware stack

and when it hits this middleware here,

it will run the user router,

because this route here is matched, okay?

And so then it enters the user router

and again, just like before,

this error is the route basically in our sub application,

and this here, is the entire URL/id, okay?

Does that make sense?

So before moving on,

let's actually test if this still works.

So, let's get all the tours here and indeed, it does.

So everything still works to the same with the users

and also that still works.

So we did all these changes and decode the works,

meaning that our two new routers are correctly mounted.

Alright, and with that, we are ready to actually separate

or different routers now into different files.

And that we will do right in the next lecture.