WEBVTT 00:03.820 --> 00:05.400 Hey, did everyone had a share? 00:05.410 --> 00:10.090 And in this video, we're going to talk again about the big promise in case you remember from one of 00:10.090 --> 00:11.020 the previous video. 00:11.050 --> 00:13.150 I told you that I'm worried about a couple of things. 00:13.150 --> 00:17.800 For example, if I go ahead and take a look onto this home controller right now, it is not connected 00:17.800 --> 00:18.550 to the database. 00:18.550 --> 00:22.930 So I'm not worried about whether the request is going to be real time or a sink of it. 00:22.930 --> 00:23.890 I have to use that. 00:23.890 --> 00:25.200 So that is one thing. 00:25.210 --> 00:28.600 The second thing I'm worried about whether the connection will actually happen or not. 00:28.600 --> 00:32.980 So I need to use a try catch block or in case I don't want to use any both of them. 00:32.980 --> 00:37.960 I need to go through and wrap everything around into a promise, a big promise. 00:37.960 --> 00:40.210 So that's exactly why I create a big promise. 00:40.210 --> 00:42.880 And I'll show you how you can use this big promise right up here. 00:42.880 --> 00:47.320 So let me let's go ahead and transform these basic home routes into these big promises. 00:47.320 --> 00:49.780 This is basically a middleware that we create. 00:49.780 --> 00:55.180 So let's go ahead and remember, whenever you create a middleware, usually like 99% of the time, you'll 00:55.180 --> 00:56.920 be using the next keyword there. 00:56.920 --> 00:58.420 So let's go ahead and use this one. 00:58.420 --> 01:05.860 So I'll be calling this one as simply Big Promise is now just like as I mentioned in the previous video, 01:05.860 --> 01:07.690 we'll be using exactly same code. 01:07.690 --> 01:10.030 So we're going to say, Hey, I want to just go ahead and export. 01:10.030 --> 01:12.550 This functions directly without even naming it. 01:12.640 --> 01:14.350 You can name it, no problem there. 01:14.350 --> 01:14.920 We have seen that. 01:14.920 --> 01:20.050 But this is how usually I do it and everybody else also that has seen they also do it exactly same. 01:20.050 --> 01:27.400 So what it does you take request response and the next obviously and you just pass it on. 01:27.400 --> 01:31.120 So I have taken a function and I have just directly handed over to this function. 01:31.120 --> 01:34.360 So I'm treating these functions as a first class citizen just like a variable. 01:34.360 --> 01:36.340 I took a variable, I pass it on as it is. 01:36.340 --> 01:37.930 So that's exactly what I'm doing. 01:37.930 --> 01:40.720 I took a function and I'm passing on exactly there. 01:40.720 --> 01:43.570 So how we are going to do it and how you are passing it up. 01:43.570 --> 01:48.820 I'm going further down the road and I'm directly saying that, hey, you will be handled by a promise 01:48.820 --> 01:49.510 itself. 01:49.510 --> 01:57.100 Now promise obviously can resolve or promise can go bad and we can go ahead and see the next catch. 01:57.250 --> 02:00.940 Now again, I would like to put up a comment for you that why we are actually doing it. 02:00.940 --> 02:11.140 So why we are doing it because I either I have to use the tri catch and we have to use a sink and think 02:11.140 --> 02:11.860 of it. 02:13.240 --> 02:18.670 And other option that we have is kind of a use promise everywhere. 02:18.670 --> 02:23.170 So that's exactly kind of a kind of a missing around the things here. 02:23.170 --> 02:28.030 So once we have this resolved, so in case the resolve is happening, that means the function is executing. 02:28.030 --> 02:34.510 So it is having a request response and the next and in case everything goes bad, then we just get the 02:34.510 --> 02:36.550 next as back again. 02:36.670 --> 02:42.040 I know this is a little bit too much because having a control over functional programming or having 02:42.040 --> 02:43.870 understanding might take a little bit. 02:43.870 --> 02:47.830 But I promise you, this is the only functional programming that I'll be using because otherwise this 02:47.830 --> 02:51.430 method becomes too long to write and it's not much useful. 02:51.640 --> 02:52.090 Okay. 02:52.510 --> 02:54.730 Once you have done this one, then how come? 02:54.730 --> 02:56.800 Actually, I go ahead and use this up here. 02:56.800 --> 02:59.380 The first thing is to bring this function up here. 02:59.380 --> 03:02.800 So what we're going to do is we are going to bring this function up here. 03:02.800 --> 03:05.140 Let's go ahead and do that at the very top here. 03:05.530 --> 03:08.800 So I'm going to call it as const, let's call it as big. 03:08.800 --> 03:11.320 I can call it anything because I didn't named it in that file. 03:11.320 --> 03:14.950 So I'm going to go ahead and call this one as big promise. 03:15.190 --> 03:23.440 And Big Promise is going to come up from require let's go one directory back of course encodes one directory 03:23.440 --> 03:28.150 back inside the middleware and inside the middleware we got this big promise. 03:28.210 --> 03:31.540 Okay, now what is going to happen once you have this big promise? 03:31.540 --> 03:33.250 Now it's really, really simple. 03:33.280 --> 03:36.100 All you got to do is now you can make anything a think of it. 03:36.100 --> 03:36.940 So I'm going to go ahead. 03:36.940 --> 03:42.460 Or even if you don't want to make it, you can just go ahead and cut this out entirely because remember 03:42.640 --> 03:47.650 our big promise except a function and what is the true definition of the function here? 03:47.650 --> 03:49.720 It starts request, response and all of that. 03:49.720 --> 03:53.890 So I can literally cut this out and I can say, Hey, big promise. 03:55.170 --> 03:55.770 There we go. 03:55.770 --> 03:58.340 And inside this big promise, I'm going to go ahead and pass it on. 03:58.350 --> 04:02.130 That's exactly that's exactly what I have to do now inside this. 04:02.130 --> 04:07.260 If I want to make it a sink and a weight, I can go ahead and say, hey, I want to use a sync and probably 04:07.260 --> 04:17.460 I'll use a weight wherever I'm declaring available const db and that is equals to await something. 04:17.760 --> 04:18.930 So something is happening again. 04:18.930 --> 04:22.710 This is just for making sure you understand what is happening, how is it happening? 04:22.710 --> 04:23.400 And that's it. 04:23.400 --> 04:24.780 That's basically all we do. 04:24.810 --> 04:29.490 We just wanted to make sure that the method that we are writing is actually in the collaboration with 04:29.490 --> 04:30.300 the promises. 04:30.300 --> 04:32.370 That's why we are wrapping everything around. 04:32.370 --> 04:37.410 So I hope this actually gives you a little bit of more clarity now that this big promise actually takes 04:37.410 --> 04:40.290 a function and try to execute that in the promise way. 04:40.530 --> 04:46.020 And remember, this is a function itself, so it receives a function and try to execute it up here. 04:46.020 --> 04:49.350 That's exactly what we are doing and we will be doing this throughout the course. 04:49.350 --> 04:53.880 Take this big promise and wrap around your regular of these methods around this big promise. 04:53.880 --> 04:55.800 And that is why Big Promise is there. 04:55.800 --> 05:00.810 In case you don't want to use Big Promise, then what you have to do, you have to use the tri catch 05:00.810 --> 05:02.850 and you have to use the async and await. 05:02.850 --> 05:06.630 So whenever you're using a single event, make sure you are using tricks. 05:06.760 --> 05:10.290 So let me give you an example of that as well in case you are getting confused here. 05:10.410 --> 05:12.150 So you have to wrap up everything. 05:13.450 --> 05:14.980 With they try and catch. 05:14.980 --> 05:23.200 So this whole thing needs to go inside up here and then handle the catcher response. 05:23.200 --> 05:24.850 Maybe you want to just log this one here. 05:24.850 --> 05:26.590 So let's go ahead and log the error. 05:26.740 --> 05:34.060 And once this is all done, then you can go ahead and make your function as a sync and same line. 05:34.060 --> 05:35.080 I can bottle that. 05:35.080 --> 05:36.010 So there we go. 05:36.280 --> 05:38.170 Okay, so which one is correct? 05:38.170 --> 05:39.140 Which one is accurate? 05:39.160 --> 05:40.270 Feel free to use anything. 05:40.270 --> 05:43.990 And there can be a third version which we discussed that, hey, just use the promises whenever you 05:43.990 --> 05:44.650 need that. 05:44.650 --> 05:48.790 And in this way I can use just my regular codes and all of that, and I can go with that. 05:48.790 --> 05:50.590 So I will be going with this method. 05:50.920 --> 05:55.360 Feel free to go ahead and use the try catch method with the thinking of it and a whole bunch of things. 05:55.750 --> 06:00.880 I know this is the most complicated part of this entire course in case you have don't have much experience 06:00.880 --> 06:05.980 with the this kind of this level of functional programming again want to use it use it. 06:05.980 --> 06:09.610 Otherwise, just make sure that you have this big promise and we'll be wrapping around everything with 06:09.610 --> 06:10.240 the vague promise. 06:10.240 --> 06:11.290 That's all I'm saying. 06:11.290 --> 06:13.330 Let's go ahead and catch up in the next video.