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Providing the client with informative HTTP status codes is part of building a useful and usable API.
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You've probably seen a 404 page
when browsing the Internet.
0:00
This status code means the server
couldn't find the requested resource.
0:03
HTTP status codes give the client
important information about the request
0:07
and response cycle.
0:11
In this video, we'll use some of
the most common http status codes.
0:13
Generally, the status codes you'll use the
most are in the 200, 400 and 500 range.
0:16
Status codes in the 200s mean
everything went as expected.
0:22
400s means something went
wrong with the request,
0:26
like a missing resource or
the wrong information was sent.
0:29
500s means something went
wrong with the server.
0:32
Something unexpected happened that
prevented the server from fulfilling
0:35
the request.
0:39
Some of the most common
status codes are 200-
0:40
OK meaning the request was successful.
0:43
201- Created,
meaning a new resource has been created.
0:46
400- Bad Request, meaning the request was
malformed or information was missing.
0:50
404- Not Found,
meaning the resource doesn't exist.
0:55
500- Internal Server Error.
0:59
See the teacher's notes for
a list of other common status codes.
1:02
>> In app.js,
scroll down to your /quotes post rout.
1:05
Let's send an error back in here and
attempt to create the quote again.
1:10
Save, make sure your server is running and
go to postman.
1:20
Try to create the quote again, and
if we scroll down to the response,
1:23
you'll see that the error message is fine,
but we have a status code of 200 OK.
1:28
That means that everything went just fine,
no problems.
1:34
That's the code that
Express sends by default.
1:37
But we have the power to choose which
status codes we send in case of error or
1:39
to give consumers of our API useful
information about the requests.
1:44
We can send a different status
code by using the status method.
1:48
Just before we send our error
message back as json here,
1:52
we can say res.status(500).
1:57
And that indicates that something
went wrong with the server and
2:01
we can actually chain these methods so
let’s do that.
2:05
Go back to postman and
send the request one more time.
2:12
Our express application is now
responding with the status code of 500.
2:15
There's also a better status code
we can with this post request,
2:21
if the request is successful.
2:25
If everything goes as expected,
it's convention to send back a status
2:26
code of 201,
which means a new resource was created.
2:31
So here we can say,
I'll delete this error first and
2:35
we can say status 201.
2:41
We can go back to postman,
send a request again and
2:48
you can see we're sending
a status of 201 created.
2:51
On the subject of status codes there's
some error handling we could do
2:54
in our single quote route.
2:57
Let's go back up to our get method
that returns a single quote.
2:59
First let's set the status of
the error in the catch block to 500.
3:05
Currently, if we go to postman and request
a quote with an ID number that doesn't
3:14
exist, we get back nothing,
a blank screen.
3:19
Let's change that so that we send an error
message and a proper status code instead.
3:21
So I'm going to set this to GET, and
3:26
let's request a jumble of letters and
numbers.
3:30
And we can close this for now.
3:36
So I'm going to change this to none.
3:38
And as you can see,
we didn't get anything back, but
3:40
we're getting the status code of 200.
3:43
Going back to app.js,
under the line that retrieves the quote,
3:45
we'll write a simple conditional.
3:49
If the quote exists,
We'll send back the quote as JSON.
3:52
So I'll just copy and
paste this line up here.
3:57
Remember, Express sends a status
code of 200 by default, so
4:02
we don't need to set the status code here.
4:06
So else, if the quote doesn't exist, we'll
set the status code to 404 not found.
4:09
And send JSON containing an error
message saying the quote wasn't found.
4:18
Let's go back to the create quote route
handler and do something similar.
4:27
Go to that route and here we'll check that
an author and a quote have been submitted.
4:31
So here we can say if req.body.author.
4:35
And req.body.quote.
4:42
Then we can go ahead and
move this code inside of this block.
4:50
Else, if one of these
properties is missing,
4:57
we can set the status code to 400.
4:59
And send back an error message.
5:04
Don't forget the message property.
5:11
A status code of 400 means bad request.
5:12
In other words something's wrong
with the syntax of the request,
5:15
information was missing, or some sort
of information validation has failed.
5:19
Sending proper status codes is
a crucial part of building a useful and
5:23
usable restful API.
5:28
Even if you're just building an API for
yourself, it can be helpful to get
5:29
confirmation that everything happened as
expected or that something went wrong.
5:33
Now unto building our update and
delete routes.
5:37
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