Heads up! To view this whole video, sign in with your Courses account or enroll in your free 7-day trial. Sign In Enroll
Well done!
You have completed PHP & Databases with PDO!
You have completed PHP & Databases with PDO!
Preview
Managing errors in any application is very important, especially when it comes to database errors. We will manage this by wrapping our code that communicates with the database with a try catch block.
If you are unable to trigger an Exception by just misspelling the database name, try changing it to look in a different location.
Such as:
$db = new PDO('sqlite:/database.db');
Notice the / instead of the ./ which is a very common error.
Related Discussions
Have questions about this video? Start a discussion with the community and Treehouse staff.
Sign upRelated Discussions
Have questions about this video? Start a discussion with the community and Treehouse staff.
Sign up
Managing errors in any application is very
important,
0:00
especially when it comes to database
errors.
0:03
We will manage this by wrapping our code
that communicates with
0:06
the database within a try catch block.
0:08
Continuing where we left off, we have
created our PDO object successfully.
0:12
And then I demonstrated how we can break
that, so, we're gonna go ahead and
0:17
break that again.
0:21
So, I'm gonna add a few more A's back in
and
0:22
see how we can handle these errors and
exceptions.
0:25
Let's go ahead and refresh this.
0:28
And now we'll see we have a fatal error,
uncaught exception.
0:30
Well, we don't want that to happen.
0:34
And if you recall from object-oriented
code practice.
0:35
We have a lot of try-catch statements when
we're trying to catch exceptions and
0:39
handle errors.
0:42
So that's what we're gonna do, we're gonna
handle this PDL exception,
0:44
by catching any general exceptions in our
script.
0:47
So head back over to the index.php file.
0:51
And then here we're gonna surround any
connection to the database.
0:54
So here where we're creating our new
database,
0:58
we're gonna actually surround that in a
try-block.
1:01
So try, then open and close our curly
braces.
1:05
Then we have a catch.
1:10
Open and close parens.
1:13
And then open and close our curly braces.
1:16
Now, this is try catch block.
1:18
Inside of here, we're gonna try any code
that we wanna run.
1:20
And if it fails out or has an exception,
we want to catch that exception.
1:25
So here we just simply put the class that
we want to catch,
1:30
which is a PDO Exception, or we can use
the parent class to catch any exception.
1:33
So, we'll type in Exception with a capital
E.
1:39
And then the next argument is the actual
exception object that gets
1:44
thrown when the error happens.
1:49
So that one we'll just call it dollar sign
e for exception.
1:51
Now we want to take this code here on line
11.
1:55
In fact we'll do line 11, 12.
1:57
We'll just copy it all.
2:00
And we'll put it inside of our try block.
2:03
So that way anything inside of
2:07
here will happen only if the succesful
database object is created.
2:09
So the other half of this coin here or the
other side of
2:15
this coin is to actually put something in
here for our exception when that happens.
2:18
So right now I'm just gonna echo a string.
2:24
In that string let's say, sorry, the
connection was not successful.
2:27
Okay?
2:37
And then I also don't want it to continue
so I'll add another die statement here.
2:38
[BLANK_AUDIO]
2:42
Close it with a semicolon.
2:44
Save our file.
2:46
And I'm gonna refresh.
2:47
So instead of it throwing an uncalled
exception, now it says,
2:49
sorry the connection was not successful.
2:52
Much cleaner, much nicer, no weird dumps
to the screen about our code.
2:53
Exactly what we want.
2:58
Now to make sure it works, we're gonna go
ahead and fix our error and then
2:59
back in here, save our file, and then
let's redo our preview.
3:07
And now we have our PDO object.
3:13
Before we continue on we do want to do 2
more things to our try-catch block or
3:16
to our PDO object and
3:21
then our actual exception to make it a
little bit more informative for us.
3:23
So let's go ahead over to a new tab and
let's open up the exception class.
3:28
We're gonna go ahead and do that.
3:33
I'm just gonna type in exception.php and
3:35
here we have exception, which shows us the
actual exception class.
3:38
If we scroll down here,
3:44
we'll see that we have several different
methods that we can use.
3:45
The one that we're going to want is
getMessage, which if we click on
3:48
getMessage information it'll just say it
gets the exception message, and
3:53
returns the exception message as a string.
3:58
Head back over to your code, here I'm
going to modify line 11,
4:01
I'm going to actually get rid of
everything there just to echo.
4:05
I'm gonna pass through the actual
exception object.
4:09
Just dollar sign e.
4:11
And then an object operator.
4:14
So that's a dash and a greater than
symbol.
4:16
Looks like an arrow pointing to the right.
4:18
And that is how we tell it that we want to
run a method.
4:20
The method that we're gonna run is
getMessage.
4:23
So get and then capital m message.
4:26
And remember it is a method, or also a
function, so
4:31
that means to call a function, we need to
use the open and close parentheses.
4:34
So we'll go ahead and do that.
4:39
And then close it, save, and now let's
refresh and see what the difference is.
4:41
Okay, connection successful, so I'll go in
here, break it again.
4:47
Save our file, then refresh.
4:53
And so now it actually gives us an
informative message more than just sorry,
4:56
I can't connect.
5:00
It actually tells you SQL state hey, we're
unable to open the database file.
5:01
All right, so that tells us we can't open
the file, maybe we did a mistake in
5:06
our connection string, which now we know
we did, so I'll go and
5:10
close that out and then hit Save.
5:13
Okay, the final step, the last thing that
we want to do, is a command on the actual
5:16
PDO object itself or a method on the PDO
object itself.
5:22
So we need to go ahead and
5:26
open up a new tab to search for the actual
PHP PDO object.
5:28
So we'll do PDO class.
5:33
Then the PHP PDO class is in the manual.
5:36
Okay and if you scroll down here you'll
see that
5:40
there are several different methods.
5:42
The one that we're interested in is
setAttribute.
5:45
So we say, setAttribute.
5:49
And then in here, you'll see there are
several constants or
5:51
the actual attributes that you can change.
5:54
That's here in the header.
5:57
So you'll see attribute case, and then
attribute error mode.
5:58
So attribute error mode or the error
reporting is what we want to modify.
6:02
So we wanna, scroll down a little bit more
here.
6:08
We wanna modify this so that the error
mode, when that happens,
6:10
anything that happens at all instead of
silencing them or having a little warning.
6:14
We actually wanna set it to throw
exception.
6:19
So no matter what the error is, we're
gonna throw an exception.
6:22
So let's go ahead and do that by calling
6:26
setAttribute on our actual PDO object,
or the dollar sign DB.
6:30
So I'll head back over to our index.php
file and we'll do it directly underneath.
6:34
So we're gonna get rid of this, and we
don't need this guy anymore.
6:41
And then here, we're gonna do $db, object
operator to setAttribute.
6:47
All right, and then close that line with a
semicolon.
6:56
Now if you go back to where we were in the
manual.
6:59
You'll see that we have the attribute and
then the value.
7:02
So, our attribute that we're gonna set,
copy this constant here,
7:05
and we're gonna paste that in.
7:10
That's our first argument.
7:14
Then we're gonna add a comma and
7:15
our second argument is the mode that we
want to set it to.
7:17
And that would be PDO error mode
exception.
7:21
Copy that paste it in.
7:26
Hit Save, and then I'm gonna do my preview
just to make sure it's all good.
7:28
Okay, we didn't do the var dump, so we
wouldn't see anything different, but
7:34
there's no errors, no exceptions, nothing
dying out.
7:38
It seems like we're right where we wanna
be.
7:41
Let's go ahead and close this guy out.
7:43
And then go back and review here.
7:46
So we've added a try catch statement to
make sure there are any exceptions that
7:48
happen on the PDO connection string, will
throw an error message to us and
7:52
then die out the script.
7:58
And then we also after creating the new
PDO object,
7:59
we have set the error mode attribute of
the PDO object or
8:03
the DB object, to throw all exceptions for
any kind of error that happens.
8:07
Next up we wanna run some queries and see
what films are in our database.
8:13
You need to sign up for Treehouse in order to download course files.
Sign upYou need to sign up for Treehouse in order to set up Workspace
Sign up