WEBVTT 00:00.350 --> 00:00.950 Okay guys. 00:00.950 --> 00:06.950 So let's do a throwback to when we implemented error handling in the first project. 00:07.100 --> 00:12.860 So a quick reminder of how the errors work in PHP. 00:13.280 --> 00:17.810 Now obviously you are talking about that because this video is about error handling. 00:19.190 --> 00:23.270 So in PHP you've got two kinds of errors. 00:23.480 --> 00:33.230 One is when there is an error that is not an exception, and the other is when there is a thrown exception 00:33.230 --> 00:36.410 that is unhandled anywhere else. 00:36.650 --> 00:44.420 Now this exists for legacy reasons because before exceptions you only had errors. 00:44.420 --> 00:51.440 So to handle errors or to customize the way it's handled, which you typically would like to do, and 00:51.440 --> 00:59.060 all the PHP frameworks do that, you need to register two functions or two callbacks. 00:59.480 --> 01:04.850 That would be one for handling exceptions and one for handling errors. 01:04.850 --> 01:08.690 And this would be what I'd like to do in this video. 01:08.720 --> 01:14.180 At least I'd like to begin, because we're gonna make it a little bit more better. 01:14.180 --> 01:23.840 So, uh, to just get straight to the point, we'd like to create an error handler class that will handle 01:23.870 --> 01:31.730 both the exceptions and errors, but also will recognize whether we are currently running inside the 01:31.730 --> 01:35.330 web server environment or inside the command line. 01:35.330 --> 01:36.320 Why is that? 01:36.320 --> 01:43.820 Because on the web server, you'd like to display an error page with different amount of information 01:43.820 --> 01:53.120 depending if we are in a debug mode or production mode, and in the command line you'd like to display 01:53.120 --> 02:02.160 the error message in the command line, you would not like to render a page, and additionally on top 02:02.160 --> 02:02.760 of that. 02:02.760 --> 02:11.220 In all cases, we'd like to log something to the error log, and this time we won't be logging everything 02:11.220 --> 02:14.760 directly to the CLI output. 02:14.790 --> 02:22.020 We'd like to store the error logs to a file so that it can be later reviewed. 02:22.050 --> 02:30.570 Okay, so without further ado, let's jump into implementing this in our current project. 02:31.860 --> 02:36.120 So let me begin with creating the new file. 02:36.240 --> 02:38.460 Now that's a core feature. 02:38.460 --> 02:42.810 So we are creating a file inside the core namespace. 02:43.560 --> 02:46.680 This would be called error handler. 02:47.700 --> 02:51.840 And it's going to be handling all types of errors. 02:51.870 --> 02:57.300 Now let's define the core namespace and the class name. 02:57.300 --> 02:59.700 That's an error handler. 02:59.700 --> 03:03.570 So the most generic Function that we need. 03:03.570 --> 03:07.170 Here is the handle exception one. 03:07.290 --> 03:09.600 Now you're going to see why. 03:09.630 --> 03:12.900 So I've said that we need to handle both. 03:12.930 --> 03:17.310 Exceptions and errors that are not exceptions. 03:17.670 --> 03:27.660 But we can do a simple trick so that everything goes through this single handle exception method. 03:27.720 --> 03:36.660 It accepts an argument of type throwable, which is something more generic than an exception. 03:37.710 --> 03:39.900 This is an exception. 03:40.620 --> 03:42.930 And let me add another one. 03:42.930 --> 03:47.730 So this would be public static function. 03:50.010 --> 03:51.720 Handle error. 03:52.350 --> 04:00.090 Now this needs some specific attributes like the error level the message the file. 04:00.090 --> 04:03.610 It happened in and on which line. 04:04.420 --> 04:05.140 Okay. 04:05.140 --> 04:10.390 So we're going to use this method to register non exception errors handling. 04:10.390 --> 04:19.270 But what I'm going to do here is I'm just going to create a new error exception. 04:19.570 --> 04:24.130 And I'm just going to pass all those parameters to it. 04:24.130 --> 04:27.580 So this would be a message. 04:29.320 --> 04:32.410 Let's just set the default code of zero. 04:32.440 --> 04:34.090 Then we're going to pass the level. 04:34.120 --> 04:41.650 As you can see I'm just passing exactly the parameters that the constructor of this exception expects. 04:42.070 --> 04:44.860 So there is also the file name. 04:45.070 --> 04:54.160 And the last is the line exactly as the parameters on this exception okay. 04:54.190 --> 04:56.620 So I'm creating a new exception. 04:56.620 --> 05:03.640 And instead of throwing it I just call handle Exception. 05:03.640 --> 05:05.590 Passing the exception. 05:06.970 --> 05:14.620 That way, this is the only place where we need to implement the actual logic of what needs to happen 05:14.620 --> 05:17.260 with any kind of errors. 05:20.440 --> 05:26.020 So what needs to happen here is first we need to log the error. 05:28.120 --> 05:35.710 And this means just log it to whatever is configured as the current logger, whether this is the output 05:35.710 --> 05:39.280 directly in the terminal or stored in a file. 05:39.640 --> 05:41.260 We're going to be handling that later. 05:41.260 --> 05:46.450 And next step is to see what environment we are currently in. 05:46.570 --> 05:53.200 So in PHP there is a function called PHP sub name. 05:53.830 --> 06:00.700 If this is CLI this means we are in a command line environment. 06:00.700 --> 06:07.990 And this would not include a up will be built in server which you start through command line. 06:08.500 --> 06:19.390 This only means scripts that are being run directly when you type, like in our case we do PHP binary. 06:19.420 --> 06:30.700 Let's say load schema PHP and if that's the case we're gonna call a method. 06:30.730 --> 06:32.590 Or maybe I can use just static. 06:32.590 --> 06:39.730 And this would be render CLI error passing the exception. 06:40.420 --> 06:48.400 Otherwise it means we have a server error on a web server, which means we need to render an error page 06:48.760 --> 06:50.740 which we also pass the exception. 06:50.770 --> 06:53.770 Now obviously those methods don't exist. 06:53.800 --> 06:55.930 We're gonna implement them next. 06:58.750 --> 06:59.140 Okay. 06:59.140 --> 07:04.580 Next thing I'd like us to work on is formatting of the error message. 07:05.030 --> 07:07.190 For that, let's define a private. 07:07.220 --> 07:13.790 Private static method that will be called format error message. 07:14.240 --> 07:25.280 And this one responsibility is to convert the exception into a string with an error message with the 07:25.310 --> 07:26.690 given format. 07:27.020 --> 07:33.560 And this will be used both to output the error on the CLI and on the website. 07:33.590 --> 07:44.360 And this accepts the variable which is exception and string which would be a format. 07:45.320 --> 07:52.280 This just means we need different formats of output on the website and on the CLI, specifically on 07:52.280 --> 07:52.940 the website. 07:52.940 --> 08:00.770 We just might want to produce a text error that's a string, but on the CLI we've got more options. 08:00.770 --> 08:08.270 We can, for example add some colors For it to be more distinguishable, that it isn't actually an error. 08:08.270 --> 08:14.450 And that's why we're going to accept different format strings. 08:14.450 --> 08:19.880 You're gonna see how exactly this works very, very soon. 08:19.880 --> 08:26.930 Anyway, we're going to use Sprintf function, to which you pass the format. 08:27.080 --> 08:37.910 And the format has some placeholders for dates, integers, etc. and then we're just gonna pass some 08:37.910 --> 08:44.630 data that we just know about the error, like we're gonna generate the current date. 08:44.630 --> 08:53.270 So current year month and day and then an hour minute and a second. 08:53.270 --> 08:56.480 That's just an exact format for a date. 08:57.350 --> 09:02.540 Then we're gonna provide the class name of the exception. 09:02.540 --> 09:06.170 You can get that using Getclass function in PHP. 09:06.620 --> 09:12.920 And next up we're going to give the message from the exception. 09:15.440 --> 09:17.390 The file from the exception. 09:17.390 --> 09:22.280 So where the error happened exactly and on which line. 09:24.140 --> 09:31.970 Now it's job of the other methods using this one format error message to come up with the proper format 09:31.970 --> 09:32.630 string. 09:32.750 --> 09:35.450 We're going to get to that very, very soon. 09:36.740 --> 09:42.470 First, maybe we can work on the errors in the CLI. 09:42.530 --> 09:49.550 And this should be a little simpler because for the web errors we also need to produce a view. 09:49.790 --> 09:55.640 So first maybe we can implement this method render CLI error. 09:58.790 --> 10:02.270 Now this method is obviously private. 10:02.300 --> 10:05.130 There is no point in making it public. 10:05.130 --> 10:07.710 It is an internal method. 10:09.180 --> 10:18.750 So it is render CLI error and it accepts variable and the name is the exception. 10:20.280 --> 10:23.820 So its void doesn't return anything. 10:24.270 --> 10:29.250 Now at this point we need to figure out if we are in the debug mode. 10:29.340 --> 10:34.050 So I'd like to use the app container and get the config. 10:34.110 --> 10:35.520 So a quick reminder. 10:35.520 --> 10:40.590 How does it look like we've got this app key and debug key inside. 10:42.300 --> 10:43.680 So we're going to use that. 10:44.400 --> 10:48.090 There is an app key which should have the debug key. 10:48.120 --> 10:54.180 If this happens to be undefined we just provide a default which is false. 10:56.700 --> 11:04.080 Next up if we are in the debug mode we're going to handle it differently than if we are not. 11:05.280 --> 11:09.210 So we need to produce the error message. 11:11.280 --> 11:17.550 And that's the time where we are using the format error message. 11:19.440 --> 11:21.690 Maybe I'm gonna use the static keyword here. 11:24.780 --> 11:28.080 And the first argument there is the exception. 11:28.080 --> 11:29.910 But the second is the format. 11:29.910 --> 11:33.000 Let's produce the format for the CLI. 11:34.740 --> 11:42.660 So in this format parameter we need to just add a placeholders which will be filled with the values 11:42.660 --> 11:43.320 in order. 11:43.320 --> 11:46.740 They are passed to the format error message. 11:46.860 --> 11:48.810 And that's the order. 11:48.810 --> 11:52.290 So we get the date the class message file and line. 11:52.710 --> 11:56.790 So I just enabled the split view so we can see that. 11:57.090 --> 12:02.160 So in the square brackets we might output the time. 12:02.520 --> 12:05.190 And this is done by adding percent s. 12:05.230 --> 12:10.480 This means we want this as a string which would relate to that date. 12:12.850 --> 12:16.360 And then we can say we've got an error. 12:17.980 --> 12:21.100 Then percent s would be the class name. 12:22.090 --> 12:28.630 We can have another colon and the percent s would be the message. 12:31.750 --> 12:46.660 Then we can say in another S string placeholder that would be the file online percent d as that's an 12:46.660 --> 12:47.260 integer. 12:47.260 --> 12:49.030 So we have a number. 12:49.360 --> 12:51.790 So D stands for decimal. 12:53.230 --> 12:55.660 At the end we can add a line break. 12:55.690 --> 13:01.660 And that would be the basic error we can display in a terminal. 13:02.290 --> 13:05.590 Now obviously I'd like to spice up things a little bit. 13:05.590 --> 13:09.220 We can close this window already. 13:09.250 --> 13:12.700 And I'd like to add some CLI colors. 13:12.730 --> 13:15.130 Now it's pretty easy to do. 13:15.160 --> 13:16.690 You just need some. 13:16.690 --> 13:19.330 You just need to know some specific symbols. 13:19.420 --> 13:27.760 So what I'm typing right here is the exact symbol that will change the color in the terminal to red. 13:29.020 --> 13:31.330 So you need this slash. 13:32.230 --> 13:39.130 Oh 33 opening square bracket 31. 13:40.030 --> 13:49.270 M so this here is an exact combo that will change the color of all the output to red. 13:49.270 --> 13:52.690 And we don't want really everything to be in red. 13:52.690 --> 13:55.720 So we need to reset that at one point. 13:56.050 --> 14:00.310 And it's up to us where to do that. 14:00.340 --> 14:03.220 Maybe we can do it right after the error. 14:03.310 --> 14:07.030 So to reset we're gonna do again. 14:07.180 --> 14:08.080 Slash. 14:08.110 --> 14:14.590 Oh 33 opening square bracket zero. 14:15.160 --> 14:20.890 M this would just reset the color to the default one, whatever that is. 14:20.920 --> 14:26.950 And that way we would have a really nicely formatted error that is super visible. 14:28.570 --> 14:30.100 But that's not everything. 14:30.100 --> 14:33.520 We can also get a so-called stack trace. 14:34.570 --> 14:39.730 So from the exception we can grab get trace as string. 14:39.730 --> 14:46.930 And what stack Trace is, is basically what were the subsequent method or function calls. 14:46.930 --> 14:50.770 So we can track what was called in what order. 14:50.770 --> 14:57.370 And potentially uh, it's easier to find the flows in the logic of your programs. 14:57.400 --> 14:59.080 We're going to see it obviously. 14:59.230 --> 15:07.190 Now, if we are not in the debug mode, then we might want a simpler error. 15:09.020 --> 15:13.040 So for such cases, we're going to have a simpler error message. 15:13.040 --> 15:17.750 And the trace would be an empty string. 15:18.320 --> 15:22.640 So you don't really want to show your stack trace of your errors. 15:22.700 --> 15:28.820 Uh, if you are not in the debug mode, even on the terminal. 15:28.850 --> 15:35.090 So here the message, I think we can still use the colors. 15:35.870 --> 15:37.760 That's why I'm copying this. 15:38.870 --> 15:40.310 And. 15:44.000 --> 15:46.160 We're going to output the error right here. 15:46.160 --> 15:49.220 And I'm going to remove everything else. 15:50.720 --> 15:53.720 So that's the changing of the color to red. 15:53.720 --> 15:55.910 And this is resetting to the default. 15:55.910 --> 16:04.910 And we're just going to say an unexpected error occurred. 16:06.770 --> 16:15.170 Please check logs or please check error log for details. 16:16.190 --> 16:17.060 And that's it. 16:17.090 --> 16:18.890 Now we can remove those spaces. 16:18.920 --> 16:22.520 I just added them so it's more clear. 16:22.520 --> 16:27.860 But remember that this is just a specific code for changing to red. 16:28.040 --> 16:34.100 And this is a specific code that terminals understand that will reset to the default one. 16:34.880 --> 16:36.590 So we are almost there. 16:36.620 --> 16:39.410 Now we need to output this someplace. 16:39.410 --> 16:44.360 And you do it using f right function. 16:44.360 --> 16:52.700 And we just say that we want to write to the so-called standard error output where we give the error 16:52.700 --> 16:53.750 message. 16:53.750 --> 17:01.940 And if we have the trace we're also going to write it to the standard error output. 17:05.450 --> 17:19.770 Where we can additionally say that maybe after a new line that the stack trace is then another trace 17:20.430 --> 17:23.190 and maybe another new line. 17:25.890 --> 17:26.340 Right. 17:26.340 --> 17:35.190 And then let's make sure we exit with an error code that's non-zero, which would mean that there was 17:35.190 --> 17:36.120 an error. 17:37.260 --> 17:37.500 Okay. 17:37.530 --> 17:42.540 So a lot of stuff was done I think that next up we should try this out. 17:42.540 --> 17:47.070 Let me comment out this line because we don't have this one implemented yet. 17:47.070 --> 17:54.420 Anyway, I think we might try to trigger some error even manually in any of the command line scripts. 17:54.420 --> 18:02.220 But we're going to do this next time, because we also need to register those new error handlers in 18:02.220 --> 18:04.050 our bootstrap file. 18:04.410 --> 18:07.890 So we're going to be testing this next up.