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Rails lets you set up "routes" for requests, so that you can send a particular request to a controller that can handle it.
To set up a route to the index of all Page objects, we add a line like this in config/routes.rb:
get '/pages', to: 'pages#index'`
In plain English, you could read this as "GET requests for the '/pages' path should go to the PagesController's 'index' method".
The result is a route like this:
$ bin/rails routes
Prefix Verb URI Pattern Controller#Action
pages GET /pages(.:format) pages#index
You can read more about GET routes in the official Rails documentation.
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A given Rails app is likely to
have a whole bunch of resources,
0:00
each with its own controller
to handle requests for them.
0:04
In our Blog app requests to create,
read, update and
0:07
delete posts are handled
by the PostController.
0:10
Now we need to add a PagesController
to handle current requests for pages.
0:13
But how will the requests
get to the PagesController?
0:17
How do we tell a request for
a post apart from a request for a page?
0:20
Rails lets you set up routes for requests.
0:24
So that you can send a particular request
to a controller that can handle it.
0:26
We'll look at how to set up routes next.
0:29
We're here in our Blog app
viewing the /post path.
0:33
It displays a list of all
our post model objects.
0:37
In this stage, we're gonna set up
a list of all our page model objects.
0:40
We're going to want that list to
be available at the /pages path.
0:44
But let's see what happens if
we try to visit that path now.
0:48
We'll change /post here
in the URL bar to /pages.
0:50
We see an error.
0:59
No route matches get /pages.
1:00
So what's this route it's referring to?
1:03
Your Rails app has several controllers,
each with several actions methods.
1:05
When Rails receives
a request from a browser,
1:09
it needs to know which
controller action to send it to.
1:12
To determine that, it looks at
the http request type and the path.
1:15
Remember, that's the part of the URL
following the server and port.
1:20
Then Rails looks for
a route to determine which controller and
1:23
which method should handle that request.
1:26
So you might have a route that says,
get requests for
1:29
the /pages path should be sent to
the PagesController's index method.
1:32
Whenever Rails receives a get request for
/pages,
1:37
it'll call the index method
on the PagesController.
1:40
You can get a list of all the routes
in a Rails app from your Terminal.
1:44
Stop the server if it's running,
1:47
and type bin/rails routes.
1:52
Windows users, don't forget to type
ruby bin\rails instead of bin/rails.
1:56
There are lots of routes for post
resources but none for page resources.
2:01
We're going to need to have one.
2:05
A Rails application's routes are
configured within the config directory.
2:07
In the routes.rb file.
2:11
This file contains Ruby code
that sets up the routes.
2:15
The syntax can be a little confusing,
2:18
especially if you're not used to
keyword arguments on Ruby methods.
2:20
Don't worry about fully
understanding it right now.
2:24
If you copy the examples we show you
here you'll be able to modify them
2:26
to suit your needs.
2:30
Let's add a route for the /pages path now.
2:31
Remember, there are several types of
HTTP requests, such as get and post.
2:34
When your browser sends a request
to view a page, it's a get request.
2:39
So we'll call the get method
to set up a get route.
2:43
As an argument to the get method,
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we need to provide the path that
this route should match as a string.
2:48
So we'll start a string and type /pages.
2:52
The next argument to
the get method is a hash,
2:55
where you can specify keys and
values with various options.
2:57
One of those is the to key,
which specifies which controller and
3:01
which action method that
request should be sent to.
3:05
So we type a key of to, and
the value should be a string.
3:07
The first part of the string is
the name of the controller we want,
3:11
with the word controller left off for
brevity.
3:13
We want our requests to go to the
PagesController, so we'll type pages here.
3:16
The second part of the string
specifies which of the controller's
3:21
action methods should handle the request.
3:23
In Ruby documentation, instance methods
of a class are marked with a hash mark,
3:26
and the same convention is followed here.
3:30
So type a hash mark, and
3:33
then the name of the action method we
want to be called, which is index.
3:34
In plain English you could read this as,
get requests for
3:39
the /pages path should go to
the PagesController's index method.
3:42
If you go back to the Terminal now and
run bin/rails routes again,
3:48
you'll see a new route
on the end of the list.
3:54
It directs get requests for
3:56
the /pages path to
the PagesController's index method.
3:58
Now that we have a route, let's try
visiting the /pages path again, and
4:03
see if the routing error goes away.
4:06
In case you're tired of typing
Rails server all the time,
4:08
let me give you a preview
of a handy shortcut.
4:11
You can just type the letter
s in place of server, so
4:14
we'll run bin/rails s
to launch our server.
4:17
Now we'll reload our page, and
the original error is gone.
4:22
Rails sees the request for
these /pages path and
4:26
tries to route it to the PagesController.
4:29
But that controller doesn't exist yet.
4:31
So instead we see the error
uninitialized constant PagesController.
4:33
We'll fix that problem next.
4:37
By the way, if you wanna read
more about get routes in Rails,
4:40
be sure to check the teacher's notes.
4:43
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