1 00:00:06,670 --> 00:00:07,990 Welcome back. 2 00:00:08,020 --> 00:00:16,149 Before we create a middleware to check if a user is logged in, let me show you another way of creating 3 00:00:16,149 --> 00:00:21,040 middleware and how we can make this off middleware chaining. 4 00:00:21,070 --> 00:00:27,130 So for this syntax, we can create the same middleware using this syntax. 5 00:00:27,220 --> 00:00:34,540 So instead of querying the function and then use it inside app to use, we can create a function directly 6 00:00:34,540 --> 00:00:36,400 inside app store to use. 7 00:00:36,430 --> 00:00:37,870 So now here we go. 8 00:00:37,870 --> 00:00:40,240 And that is going to be the middle word. 9 00:00:40,330 --> 00:00:44,380 So here we can make use of normal function or function for this one. 10 00:00:44,380 --> 00:00:52,270 Let's make use of normal function and you have access to requests, response and the next function and 11 00:00:52,270 --> 00:00:55,510 here you go so I can go ahead and console.log. 12 00:00:55,510 --> 00:01:02,770 This one, which is the same thing now I can comment this one, and now if I save it and I make a request 13 00:01:02,770 --> 00:01:05,470 to that root and now check it out. 14 00:01:05,470 --> 00:01:14,740 Inside I see a logo, but I don't see the response, meaning that I'm not calling next inside this middle 15 00:01:14,800 --> 00:01:15,330 word. 16 00:01:15,370 --> 00:01:16,660 That is the problem. 17 00:01:16,660 --> 00:01:18,490 So now let me call it as that. 18 00:01:18,490 --> 00:01:19,150 Save it. 19 00:01:19,150 --> 00:01:21,850 And now let's make the request again. 20 00:01:21,850 --> 00:01:27,670 I have my response and I have my middleware being called, which is awesome. 21 00:01:27,670 --> 00:01:31,630 So any of these ways we can create a merge word. 22 00:01:31,840 --> 00:01:35,720 So now what about chaining of middleware? 23 00:01:35,740 --> 00:01:37,420 So here we go. 24 00:01:37,600 --> 00:01:48,400 Now let me comment this one and let me give it a beautiful comment here says chaining matter where. 25 00:01:48,490 --> 00:01:49,510 So here we go. 26 00:01:49,510 --> 00:01:57,990 We make use of app dot use and inside we pass in a callback function which is our middleware. 27 00:01:58,000 --> 00:02:07,510 So the first one have access to request response and then next and then every function has that. 28 00:02:07,960 --> 00:02:11,470 So here I'll console.log the first middleware. 29 00:02:11,470 --> 00:02:15,130 I would say that first middle. 30 00:02:15,950 --> 00:02:16,760 Where. 31 00:02:16,910 --> 00:02:19,720 And let me call it next hearing. 32 00:02:19,730 --> 00:02:21,000 And here we go. 33 00:02:21,050 --> 00:02:30,350 And then on that, I can change by make use of dot and then use and I can add any callback function 34 00:02:30,350 --> 00:02:32,150 here, which is a murderer. 35 00:02:32,150 --> 00:02:38,600 So I can copy this one and now paste it here as that as my second murderer. 36 00:02:38,600 --> 00:02:42,290 And I'll change this one to second murderer. 37 00:02:42,290 --> 00:02:49,580 And to change more I'll make use of dot and use and then paste in my callback function as that and change 38 00:02:49,580 --> 00:02:54,560 this one to third middle where let me change this one to uppercase. 39 00:02:54,560 --> 00:02:59,810 And now I can change as many as I want in the pipeline. 40 00:03:00,050 --> 00:03:00,470 All right. 41 00:03:00,470 --> 00:03:03,800 So now when I save this one, I make a request. 42 00:03:03,800 --> 00:03:05,060 Now check it out. 43 00:03:05,090 --> 00:03:06,080 Let's see. 44 00:03:06,080 --> 00:03:10,310 First were just called, second one called and third also called. 45 00:03:10,670 --> 00:03:11,150 All right. 46 00:03:11,150 --> 00:03:12,740 But inside the first middle. 47 00:03:12,740 --> 00:03:19,790 Well, let's see that I refuse to break next what is going to happen, meaning that after this one being 48 00:03:19,790 --> 00:03:25,280 called the next middle way here will not be called because I'm not calling next year. 49 00:03:25,280 --> 00:03:26,720 So let's check it out. 50 00:03:26,750 --> 00:03:29,450 Moment of truth when I hit send. 51 00:03:29,450 --> 00:03:30,830 Now, let's see. 52 00:03:30,830 --> 00:03:35,900 You can see that I get the first middle way because that is the first one in the pipeline. 53 00:03:35,900 --> 00:03:41,960 And since I'm not calling, next express is still hanging waiting for the next to be called. 54 00:03:42,230 --> 00:03:48,020 But as soon as I provide next to this one as that. 55 00:03:50,700 --> 00:03:54,720 And when I say it now, let me remove this one here. 56 00:03:54,750 --> 00:03:56,100 So let's see the flow. 57 00:03:56,130 --> 00:04:01,980 The first one will console.log and then move to the next middleware, which is this one, and it will 58 00:04:01,980 --> 00:04:02,550 call. 59 00:04:02,550 --> 00:04:04,800 But after that there is no next. 60 00:04:04,800 --> 00:04:09,540 So it will stop here and the rest of the code down here will not run. 61 00:04:09,540 --> 00:04:11,120 So let's check it out. 62 00:04:11,130 --> 00:04:18,089 When I make the request and I check my terminal, you can see that I have first, second and third guys 63 00:04:18,089 --> 00:04:19,440 take note about this. 64 00:04:19,649 --> 00:04:23,660 The order of a middleware matters a lot. 65 00:04:23,700 --> 00:04:25,620 So here is the clue. 66 00:04:25,650 --> 00:04:33,180 Always put your middleware at the top before your route handles, because this is the first middleware 67 00:04:33,180 --> 00:04:33,960 here. 68 00:04:33,960 --> 00:04:36,230 And next is those down here. 69 00:04:36,240 --> 00:04:38,700 That is a route I also made reverse. 70 00:04:38,880 --> 00:04:45,810 So this one will call and then the next minute will be called by if I cut this one. 71 00:04:46,640 --> 00:04:50,690 Cut it and then let me place it below all my roots here. 72 00:04:51,590 --> 00:04:58,520 Even though let me remove the next one here and remove this one, meaning that by default the response 73 00:04:58,520 --> 00:04:59,660 will never be displayed. 74 00:04:59,660 --> 00:05:02,130 But let's check it out when I make the request. 75 00:05:02,150 --> 00:05:09,050 You can see that I get a response and when I check my terminal there is no matter where being called 76 00:05:09,080 --> 00:05:11,500 is because of the order. 77 00:05:11,510 --> 00:05:15,040 So pay attention about the order. 78 00:05:15,050 --> 00:05:18,740 So let me bring it back to the top here. 79 00:05:18,950 --> 00:05:24,110 So this is how we can change middleware and how we can arrange middleware. 80 00:05:24,290 --> 00:05:30,980 The next video, let's see how we can create a measure to check if a user is logged in.