WEBVTT 00:00.500 --> 00:07.700 So in this video, we are going to be talking about errors about how to handle built in PHP. 00:07.730 --> 00:16.430 Errors and exceptions and how to do that the most secure way, and the way that will also give you the 00:16.430 --> 00:19.610 necessary information about what has happened. 00:20.360 --> 00:24.230 So this app is currently lacking any error handling. 00:24.230 --> 00:32.810 And we need to add some error handling because every serious application needs a way to deal with errors. 00:32.810 --> 00:40.520 And in PHP we've got two kinds of errors the built in errors, warnings and notices. 00:40.760 --> 00:50.000 This was initially the way PHP reported errors, and it also outputted those errors on the screen directly. 00:50.210 --> 00:52.490 You're gonna see in a second what I mean. 00:52.490 --> 00:56.510 And another kind of errors are exceptions. 00:56.600 --> 00:59.240 This was introduced later in PHP. 00:59.270 --> 01:04.790 That's why we have two kinds of errors that can happen in PHP. 01:05.750 --> 01:09.830 First, let me trigger the traditional PHP error. 01:09.980 --> 01:17.630 This can happen, for example, if I echo or use a variable that wasn't initiated first. 01:17.630 --> 01:22.280 So this hey variable obviously doesn't exist anywhere in here. 01:22.310 --> 01:26.360 That's why this should cause some kind of an error. 01:26.360 --> 01:33.200 And by default, in most modern versions of PHP this would be reported in console. 01:33.320 --> 01:35.330 So let me refresh this page. 01:35.330 --> 01:41.060 You can see this is not reported on this page that this variable is not defined. 01:41.060 --> 01:49.490 But inside the console where PHP server runs, we can see a PHP warning that we are using an undefined 01:49.490 --> 01:50.540 variable. 01:50.540 --> 01:55.010 So it is good that PHP changed this behavior because. 01:55.010 --> 01:59.270 Now let me show you how this looked like before. 01:59.300 --> 02:07.730 So this word times in older versions of PHP, and I think that every single one of you have seen this 02:07.760 --> 02:13.790 online popping up randomly on some older websites using WordPress. 02:13.820 --> 02:20.870 So first let's set the error reporting level to display all errors. 02:20.900 --> 02:22.370 This is how you do that. 02:22.490 --> 02:32.360 And we're gonna set using any set method the setting called display underscore errors. 02:32.360 --> 02:37.040 In modern PHP versions this is disabled by default. 02:37.040 --> 02:39.410 And that's the right thing to do. 02:39.710 --> 02:43.190 Let's just enable it so you can see what I mean. 02:43.190 --> 02:47.150 Now when I refresh this page this is what I was talking about. 02:47.150 --> 02:52.610 I guess every single one of you, even if you didn't know that is PHP. 02:52.640 --> 02:56.270 You seen that on at least one website. 02:56.300 --> 02:58.790 I think it's terrible. 02:58.790 --> 03:00.860 It's ugly error reporting. 03:00.860 --> 03:09.320 And it is unsafe because it is telling the random visitor of the website what language you are using, 03:09.320 --> 03:17.870 what framework you are potentially using, and where your files are kept, and also what PHP file had 03:17.870 --> 03:18.650 the error. 03:18.650 --> 03:23.270 So it's great that now it is disabled by default. 03:23.270 --> 03:28.190 Let's comment this out then it's enough to see it in the console. 03:29.060 --> 03:32.810 So another kind of errors are exceptions. 03:33.290 --> 03:36.770 So you already know a little about exceptions. 03:36.770 --> 03:45.320 And you can throw your own exceptions or just handle the exceptions produced by some PHP libraries. 03:45.440 --> 03:54.320 For example PDO can produce some exceptions if for example you can't connect to database, you can't 03:54.320 --> 03:56.810 insert it to data to the database. 03:56.810 --> 04:01.010 Can't read the data or there are some database errors. 04:01.040 --> 04:07.310 Like for example, you are trying to insert a record that already exists. 04:07.310 --> 04:15.620 So typically, the most modern solution to any kind of errors in PHP is to throw an exception. 04:15.740 --> 04:23.240 So this is what I was talking about earlier, that we don't really have any error handling in this app, 04:23.240 --> 04:25.550 so we need to handle exceptions. 04:25.550 --> 04:31.940 Before we do, let me trigger an exception manually so we can see how it looks like. 04:31.940 --> 04:38.090 So you do it using throw and you create just a new instance of the exception. 04:38.090 --> 04:43.160 It can be let's use runtime exception saying whoops. 04:44.540 --> 04:49.250 Now let me refresh the page and jump back to the terminal. 04:49.250 --> 04:54.020 So the page that was returned isn't really telling us anything. 04:54.020 --> 04:56.330 It looks really broken. 04:56.330 --> 05:00.860 So that is not even a page that we have created. 05:00.860 --> 05:04.040 This is the default browser page. 05:04.040 --> 05:10.970 And when we take a look at the terminal, it contains a little bit more information about the error 05:10.970 --> 05:14.240 that we maybe can use for debugging. 05:14.240 --> 05:24.230 So our goal would be to create some common error page that will give our users more confidence that 05:24.230 --> 05:31.250 something bad has happened, but maybe they can try again not to display this really terrible page that 05:31.250 --> 05:36.320 looks like everything just went completely wrong and there is no recovery. 05:36.440 --> 05:40.310 And also to handle those errors the same way. 05:40.310 --> 05:49.160 Doesn't matter if there is a built in PHP error, or an exception is thrown by either our code or some 05:49.160 --> 05:51.710 built in PHP code. 05:52.460 --> 05:54.320 Now let's get to it. 05:54.350 --> 05:59.060 Let's see how can we change the way errors are handled in PHP? 05:59.810 --> 06:05.930 Now, I think that we should start with handling exceptions in a better way because as you can see right 06:05.960 --> 06:11.090 now, currently if an exception happens, it is pretty catastrophic. 06:11.120 --> 06:17.270 The whole page basically disappears and we see some default browser page. 06:17.300 --> 06:24.170 Now we need to remember that exceptions can still be handled inside a try catch block. 06:24.200 --> 06:29.990 That's best for when you expect a certain exception can be happening. 06:29.990 --> 06:37.310 For example, with database connections it's quite possible that something would go wrong. 06:37.340 --> 06:44.480 Now, currently we just need to add a handler that will handle unhandled exceptions. 06:44.480 --> 06:50.660 However, this sounds so exceptions that weren't handled by our try catch block. 06:50.660 --> 06:54.320 And they are really unexpected. 06:54.740 --> 07:02.450 So without any changes here, let's jump to the bootstrap PHP file, because this is where I'd like 07:02.450 --> 07:04.790 to set up the error handling. 07:05.150 --> 07:08.180 So we want to report all the errors. 07:08.180 --> 07:13.610 And another function that will be useful is set exception handler. 07:13.640 --> 07:21.260 That's just a PHP function that will let us create our own custom way to handle exceptions. 07:21.500 --> 07:23.390 So we need to call it. 07:23.570 --> 07:26.300 This is set exception handler. 07:26.300 --> 07:31.190 And we pass a callable here which is just a function. 07:31.220 --> 07:33.440 Now we need to create one. 07:33.470 --> 07:37.850 I think we can create another file just for errors. 07:37.850 --> 07:40.820 I'm going to call it error handling. 07:40.910 --> 07:44.810 And it's really crucial for our app. 07:44.810 --> 07:50.060 That's why I think it can be on the same level as the bootstrap file. 07:50.090 --> 07:56.990 Also, I think that the error handling should be one of the first things that happen inside the bootstrap 07:56.990 --> 07:57.770 file. 07:57.800 --> 08:04.070 I think it's pretty obvious because if we would move it at the end of the bootstrap file, all those 08:04.070 --> 08:11.270 things that happen in between can potentially cause some errors, which would be then not really properly 08:11.270 --> 08:13.190 reported and handled. 08:13.220 --> 08:18.890 That's why it's important to do it as the first thing now. 08:18.920 --> 08:26.600 That's also why we're gonna use require once and just require this error file right away. 08:26.840 --> 08:29.690 So this is error handling PHP. 08:31.010 --> 08:37.490 And now let's jump back to this file and create our custom exception handler. 08:37.550 --> 08:39.470 So we need to pass a function here. 08:39.470 --> 08:41.930 Let's see how this function should look like. 08:41.930 --> 08:51.470 So it should only accept one parameter of type throwable which can be Of type error or exception. 08:51.470 --> 08:54.410 That's why we type it with an interface. 08:54.470 --> 08:56.510 So let me add a function called. 08:56.540 --> 09:01.940 Exception handler that accepts throwable. 09:05.150 --> 09:08.150 And it doesn't really return anything. 09:08.150 --> 09:12.740 And let's implement some better exception handling. 09:14.780 --> 09:20.570 Let's begin by producing a message that we are about to log. 09:20.600 --> 09:25.070 The same as things are currently logged in the terminal. 09:25.070 --> 09:28.220 So I just want a custom message. 09:28.400 --> 09:33.290 So we say that this was an uncaught exception. 09:33.290 --> 09:37.760 That's important to just say it that it wasn't caught. 09:38.480 --> 09:43.730 Next up we need to concatenate with the actual class name of this exception. 09:43.730 --> 09:46.070 This is important information. 09:46.070 --> 09:50.830 For this we can just use the getclass function of PHP. 09:50.860 --> 09:57.910 Passing this argument that I've called the exception, you can customize the name of that argument. 09:58.510 --> 10:01.720 Then concatenate to close the parentheses. 10:01.720 --> 10:08.920 That's just the beginning because next up we are going to sorry the colon goes in here. 10:09.850 --> 10:17.230 Next up we concatenate that with further information from this exception object. 10:17.470 --> 10:23.290 Because it contains the actual message we can get it through a method. 10:23.830 --> 10:29.140 And next up let's also say in what file this happened. 10:29.170 --> 10:32.470 Keep in mind this is information for us. 10:32.470 --> 10:34.750 We're going to be logging this. 10:34.750 --> 10:36.970 This is not displayed to the user. 10:37.120 --> 10:42.010 So from exception we can also get the file name. 10:42.100 --> 10:55.750 And additionally It's also concatenate this with online and say basically in which line this has happened. 10:55.780 --> 11:02.290 This would be exception get line. 11:02.290 --> 11:06.100 So that's the full message I'd like us to output. 11:06.130 --> 11:13.660 Now in PHP there is this error log message that will put that on the console. 11:15.250 --> 11:16.480 So let's do it. 11:16.480 --> 11:25.450 And the rest let's just use the function we already have returning 500 code, but with some response 11:25.450 --> 11:32.080 we're gonna say an unexpected error occurred. 11:33.970 --> 11:39.220 Please, please try again later. 11:40.810 --> 11:48.370 So as you see as little as possible information will be getting to the visitors of our website. 11:48.370 --> 11:54.430 And this is intentional because they won't be fixing the errors in our code. 11:54.430 --> 11:57.370 That's why they don't need to know the actual message. 11:57.400 --> 12:03.190 Exception, and especially the file and line in which this has happened. 12:03.880 --> 12:11.770 Now the final step is to jump to bootstrap and just pass a string with the function name that will handle 12:11.770 --> 12:13.300 those exceptions. 12:13.330 --> 12:19.870 After those changes, I should be able to refresh this page and see a nicer message. 12:19.900 --> 12:24.100 Now nothing stops us from actually rendering a view. 12:24.100 --> 12:26.890 So we've got this templates folder. 12:26.890 --> 12:36.610 We can create a whole page including the header and footer called maybe 404 or 500 specific for errors 12:36.610 --> 12:42.430 that will display the whole page with a very nice error and maybe very nice error message. 12:42.430 --> 12:46.510 I mean, and maybe some instructions on how to recover. 12:46.510 --> 12:51.580 But I think that for the purpose of demonstration, that's enough. 12:51.970 --> 13:00.160 And also, let's jump to the terminal where we have our custom message that uncaught exception with 13:00.160 --> 13:04.780 the class name has happened with the message and all the other info. 13:06.910 --> 13:12.610 So another thing to handle apart from exception handler is this error handler. 13:12.640 --> 13:17.470 So let's see the function set error handler. 13:18.460 --> 13:21.160 That's the next one that we would have to call. 13:21.190 --> 13:22.810 This is set error handler. 13:22.810 --> 13:26.320 And obviously we need to prepare this handler first. 13:26.320 --> 13:33.940 That's why we're gonna jump to error handling and create another function that can handle the non exception 13:33.940 --> 13:35.530 errors in PHP. 13:35.830 --> 13:39.820 So let's take a look at this set error handler function. 13:39.820 --> 13:42.370 The first argument to it is callable. 13:42.400 --> 13:45.790 But notice that it is nullable. 13:46.600 --> 13:49.660 This means we can pass null to this function. 13:49.660 --> 13:54.250 What's the point of that if we are about to set a custom error handler? 13:54.280 --> 14:02.050 Well, the point is that if you pass null, it resets any custom handlers that you have assigned before 14:02.080 --> 14:05.830 going back to the default PHP behavior. 14:06.640 --> 14:11.650 Now let's see how our function that we are about to create should look like. 14:11.650 --> 14:13.900 So this is the handler. 14:14.740 --> 14:20.110 So here you can read that passing null will reset to the default PHP handler. 14:20.140 --> 14:25.060 Now let's create a function that we can call error handler. 14:25.090 --> 14:28.990 As you can see this function needs to return a boolean. 14:29.020 --> 14:32.950 We're going to explain why and the arguments here. 14:33.190 --> 14:37.990 So we've got an integer the error number. 14:38.230 --> 14:42.790 Then a string error string. 14:42.820 --> 14:46.420 This is a kind of a message. 14:46.570 --> 14:54.850 And additionally we've got a string error file and then an integer. 14:54.880 --> 14:58.360 This is an error line. 14:58.360 --> 15:01.870 So line in that file where the error has happened. 15:01.870 --> 15:03.070 And the context. 15:03.070 --> 15:05.710 Well we can accept this argument or not. 15:05.740 --> 15:07.180 It's up to us. 15:07.390 --> 15:09.880 So maybe this is enough. 15:09.910 --> 15:14.350 The first step is to construct a message that we're going to log. 15:14.350 --> 15:16.360 So this is only for us. 15:16.360 --> 15:23.650 We can say that the error with the error number. 15:26.680 --> 15:32.980 Then let's display the message on line. 15:34.090 --> 15:38.650 Next up we display the line in file. 15:38.680 --> 15:39.940 And. 15:42.340 --> 15:45.490 This is error file. 15:45.490 --> 15:50.800 So this is a thing that we are about to log using error log. 15:51.160 --> 15:52.330 That's a message. 15:52.330 --> 16:01.270 And again here we're going to use the server error not to display too many info about what has happened. 16:01.270 --> 16:04.630 Remember this is an unexpected thing. 16:04.630 --> 16:07.690 So something probably gone terribly wrong. 16:07.690 --> 16:11.200 So we just say an error occurred. 16:13.870 --> 16:17.350 Please try again later. 16:17.350 --> 16:19.360 So we display the message here. 16:19.360 --> 16:22.660 And then to the user to the visitor. 16:22.660 --> 16:28.240 We just call the server error function with some message that is very generic. 16:28.420 --> 16:34.990 That unexpected error occurred. 16:35.140 --> 16:38.500 Please try again later. 16:39.280 --> 16:45.520 Now, even if we have a notice or warning, this is typically something that can really go terribly 16:45.520 --> 16:46.090 wrong. 16:46.090 --> 16:53.470 Previously, PHP ignored that by either logging this info or displaying it on page and trying to continue. 16:53.470 --> 17:02.500 But I think that you should always fix all the issues and all the errors, like accessing a non-existing 17:02.500 --> 17:05.890 key in array or using a non-existing variable. 17:05.890 --> 17:12.340 I don't think you should be leaving those errors unattended and ignore them. 17:12.340 --> 17:19.810 And this returns a boolean, because now we are just telling PHP whether this concludes the error handling. 17:19.810 --> 17:21.280 If you return true. 17:21.760 --> 17:28.480 PHP won't do anything, won't handle this internally with the default behavior, but if you return false. 17:28.990 --> 17:36.670 PHP will also handle this error internally by doing how it is configured to behave, either displaying 17:36.670 --> 17:40.390 this on screen Sunscreen are just logging the error. 17:40.390 --> 17:45.520 So finally we need to jump to bootstrap and register this function. 17:45.520 --> 17:48.340 This is error handler. 17:49.540 --> 17:53.680 And then let's jump to our page where we trigger the errors. 17:53.680 --> 17:59.290 Comment out this and try to echo a non-existing variable. 17:59.320 --> 18:00.970 Now refresh this page. 18:00.970 --> 18:07.690 We see the error, the generic error, and in the console we've got more info. 18:08.110 --> 18:13.090 We've got the error the error number what's the message and where it happened. 18:13.810 --> 18:19.870 So now we can comment out this error because we just wanted to trigger something to see how this would 18:19.900 --> 18:20.500 behave. 18:20.500 --> 18:26.290 But I consider the error handling more or less done for this project. 18:26.290 --> 18:33.580 We can obviously improve error handling by handling exceptions, but I'm gonna leave it as an optional 18:33.580 --> 18:36.880 thing for the end of this project.