WEBVTT 1 00:00.650 --> 00:02.360 Hi everyone. 2 00:02.780 --> 00:06.260 Let's understand the pipes. 3 00:08.450 --> 00:11.480 Into the core concept of Nestjs. 4 00:12.590 --> 00:13.100 Okay. 5 00:13.460 --> 00:16.700 The pipe is a class within the injectable. 6 00:16.730 --> 00:19.160 It means it's a dependency injection. 7 00:22.550 --> 00:22.970 Okay. 8 00:22.970 --> 00:25.370 It implement from PipeTransform interface 9 00:25.700 --> 00:27.650 but ignore that. 10 00:28.520 --> 00:34.250 Let me show you the idea of the pipes. 11 00:34.640 --> 00:39.050 The pipe, it's have two use cases 12 00:39.650 --> 00:42.980 You can see, the first one will be transformation. 13 00:43.070 --> 00:47.750 It can be transform the input into the some output. 14 00:47.780 --> 00:50.600 For example, from string to integer. 15 00:51.770 --> 00:53.900 It has some validation rule. 16 00:54.980 --> 01:00.980 Okay, now let me show you something like this. 17 01:01.520 --> 01:07.040 And notice about built-in pipe, in NestJS. 18 01:07.070 --> 01:08.120 It has a nine. 19 01:08.300 --> 01:10.310 9 pipes 20 01:14.180 --> 01:16.100 Something like validation. 21 01:16.130 --> 01:21.620 Okay, but before understand pipes, let me show you. 22 01:21.620 --> 01:22.490 What is the @Get(':id') 23 01:23.030 --> 01:25.790 right here and @Param right here 24 01:25.790 --> 01:26.720 What is mean? 25 01:27.080 --> 01:27.500 Okay. 26 01:29.240 --> 01:33.080 After we understand that, we will understand the pipes. 27 01:33.620 --> 01:34.490 Let me show you. 28 01:34.520 --> 01:38.120 For example, inside the post controller. 29 01:38.870 --> 01:40.400 Inside the post controller. 30 01:41.330 --> 01:41.600 Okay. 31 01:41.600 --> 01:47.510 Let me collapse the code right here, inside the post controller. 32 01:50.180 --> 02:01.460 For example, I will create one more method I will call method will be the getPost, and with the 33 02:01.460 --> 02:05.750 id okay, it means I want to get the post. 34 02:05.750 --> 02:05.780 ... 35 02:05.810 --> 02:17.330 For example, if I go to the postman and "/1" right here, I want it will pass the "1" inside 36 02:17.360 --> 02:23.060 the controller and find that for me, how we can do that. 37 02:23.660 --> 02:31.490 Firstly, in order to use that, to access the "id" parameter, we must. 38 02:31.520 --> 02:39.470 We must use the @Param id: number, for example like this. 39 02:40.340 --> 02:42.950 Now we can see, I will use the @Param. 40 02:45.800 --> 02:46.160 Right. 41 02:46.430 --> 02:50.030 It will be the "id" and make sure here and here will be the same. 42 02:52.190 --> 03:03.740 And "id" okay, we can pass this something like this if you want, but I will say the id: number 43 03:05.570 --> 03:07.100 and you will getOne. 44 03:08.510 --> 03:10.490 And now let me console.log. 45 03:10.490 --> 03:12.890 What is inside the "id" for you? 46 03:13.370 --> 03:14.480 check post 47 03:14.510 --> 03:14.990 id 48 03:16.610 --> 03:16.940 id 49 03:23.030 --> 03:29.120 If I send and the check post id will be 1 because I passed the 1 right here. 50 03:29.690 --> 03:30.080 Two. 51 03:31.040 --> 03:31.550 Okay. 52 03:31.730 --> 03:32.660 It will be the post. 53 03:32.690 --> 03:33.230 Two. 54 03:34.070 --> 03:34.550 Okay. 55 03:34.580 --> 03:35.300 That's the param 56 03:39.380 --> 03:40.580 And. 57 03:43.130 --> 03:53.510 For now, let me write the code for post service, if I go to post service right here and I will. 58 03:53.600 --> 03:55.640 I will remove the throw. 59 03:56.300 --> 04:03.620 I will pass the get one and I will accept within the "id". 60 04:03.650 --> 04:05.690 I will take the "id", right? 61 04:06.140 --> 04:07.220 It will be the number. 62 04:07.550 --> 04:10.490 And I will use the data. 63 04:11.270 --> 04:14.690 .find will be "post" 64 04:15.650 --> 04:16.880 equal post 65 04:16.910 --> 04:19.610 dot id 66 04:19.640 --> 04:21.290 The "id" from parameter. 67 04:21.830 --> 04:22.400 Okay. 68 04:22.790 --> 04:26.270 After we find us, we will return. 69 04:27.620 --> 04:28.850 We will return the data. 70 04:28.880 --> 04:32.510 This is clearly the business logic. 71 04:33.170 --> 04:36.290 Actually I must do that in the repository. 72 04:36.770 --> 04:42.230 But don't worry it for now, I will use get one. 73 04:42.710 --> 04:46.670 Get one and I will pass the "id" 74 04:47.330 --> 04:49.490 Now let's see. 75 04:55.130 --> 04:55.760 If I send. 76 04:58.850 --> 05:01.910 The word two actually is not work. 77 05:23.710 --> 05:24.580 Let me see. 78 05:31.090 --> 05:35.740 Now, the reason it not work because. 79 05:37.900 --> 05:44.140 if I change the "===" into "==" 80 05:44.710 --> 05:45.280 Okay. 81 05:46.720 --> 05:48.910 If I send, sorry. 82 05:49.030 --> 05:53.200 If I send it works, why? 83 05:53.590 --> 05:55.960 Why's that? It's a little bit weird 84 05:56.050 --> 05:56.710 Right? 85 05:57.190 --> 05:58.810 You can see this is the number. 86 05:58.930 --> 06:00.250 This is the number. 87 06:00.280 --> 06:02.350 But why it not work? 88 06:04.060 --> 06:07.660 Let me tell you the reason why it not work, firstly 89 06:07.690 --> 06:15.250 I will console.log typeof "id", can you guess it is string or number? 90 06:16.660 --> 06:18.910 now it's, I guess. 91 06:18.940 --> 06:20.800 It's clearly a string. 92 06:21.490 --> 06:24.400 You can see this is clearly a string. 93 06:26.350 --> 06:27.700 And the typescript right here. 94 06:27.700 --> 06:28.870 It doesn't check. 95 06:29.980 --> 06:30.610 Okay. 96 06:30.640 --> 06:31.570 It doesn't check. 97 06:32.530 --> 06:35.920 It leaves the developer okay. 98 06:35.950 --> 06:37.540 So it doesn't check. 99 06:38.590 --> 06:42.550 And because the string is not compare with the "===" like this. 100 06:42.730 --> 06:43.600 Right? 101 06:43.810 --> 06:48.580 And for that reason, we must convert it into the number. 102 06:48.790 --> 06:49.330 Right. 103 06:49.360 --> 06:53.710 And for that reason I can convert it using the "+" 104 06:54.430 --> 07:01.960 "+" before "id", if I send okay, it's already worked. 105 07:02.650 --> 07:03.310 But. 106 07:05.710 --> 07:06.070 With. 107 07:06.070 --> 07:11.590 NestJS we can use a pipe, right here. 108 07:11.650 --> 07:17.650 We can convert this using the ParseIntPipe, right 109 07:18.130 --> 07:23.530 So if I use the second parameter "ParseIntPipe" 110 07:24.580 --> 07:26.950 If I console.log typeof 111 07:28.420 --> 07:28.810 id 112 07:35.020 --> 07:37.420 Now you can see it already worked right. 113 07:37.420 --> 07:41.260 And the type will be the number. 114 07:41.560 --> 07:44.890 And that's the reason we use pipe. 115 07:47.020 --> 07:47.500 Okay. 116 07:49.390 --> 07:52.810 So now let's go to the use case. 117 07:52.810 --> 07:58.750 You can see, the pipe it will transform the string into the integer right. 118 07:58.780 --> 08:00.220 This is the first use case 119 08:00.400 --> 08:02.530 And let's see what is the difference. 120 08:03.070 --> 08:04.690 The second use case. 121 08:07.420 --> 08:18.010 If I scroll down a little bit and because we use the ParseIntPipe, it already validation the param 122 08:18.010 --> 08:18.610 for me. 123 08:18.850 --> 08:21.490 If I pass something here. 124 08:21.910 --> 08:23.170 ABCXYZ? 125 08:26.050 --> 08:31.240 And now you can see, it showed a message validation failed numeric 126 08:31.870 --> 08:32.260 Okay. 127 08:32.290 --> 08:33.670 String is expect. 128 08:35.980 --> 08:41.770 For that reason, we will use the numeric string like: 2,3,4 129 08:42.910 --> 08:43.330 Right. 130 08:44.020 --> 08:44.800 Very cool. 131 08:45.220 --> 08:50.260 And I hope you understand what is the "pipe" right now. 132 08:50.380 --> 09:01.030 And we can use the some different "pipe" like ParseFloatPipe, or something like this to validation 133 09:02.110 --> 09:02.560 okay. 134 09:02.590 --> 09:04.990 To validation the param 135 09:09.640 --> 09:15.580 Let me see, we have something like this or not okay. 136 09:17.590 --> 09:20.230 Anyway, this is the pipe 137 09:20.230 --> 09:21.760 I hope you understand this video. 138 09:21.790 --> 09:23.560 I will see you in the next one.