1 00:00:01,330 --> 00:00:02,860 ‫Another nice small feature 2 00:00:02,860 --> 00:00:04,910 ‫that we can add to an API is 3 00:00:04,910 --> 00:00:08,070 ‫to provide an alias route to a request 4 00:00:08,070 --> 00:00:09,660 ‫that might be very popular, 5 00:00:09,660 --> 00:00:11,963 ‫so it might be requested all the time. 6 00:00:13,400 --> 00:00:15,260 ‫And, for example, we might want 7 00:00:15,260 --> 00:00:17,790 ‫to provide a route specifically 8 00:00:17,790 --> 00:00:20,203 ‫for the five best cheap tours. 9 00:00:21,324 --> 00:00:23,530 ‫So, if we'd use our regular route here 10 00:00:23,530 --> 00:00:25,530 ‫with the filters and with all the features 11 00:00:25,530 --> 00:00:26,580 ‫that we already have, 12 00:00:26,580 --> 00:00:29,930 ‫the request would look a little bit like this. 13 00:00:29,930 --> 00:00:32,090 ‫So, let's get ride of all of this. 14 00:00:32,090 --> 00:00:34,510 ‫So, the five best and cheapest tours. 15 00:00:34,510 --> 00:00:37,340 ‫So, that means we have a limit of five 16 00:00:39,495 --> 00:00:42,663 ‫and then we're gonna sort by ratings and by price. 17 00:00:44,300 --> 00:00:47,640 ‫So, sort and then the average rating, 18 00:00:47,640 --> 00:00:52,640 ‫and descending, so minus ratings average. 19 00:00:54,110 --> 00:00:56,750 ‫And, in case they have the same average, 20 00:00:56,750 --> 00:00:59,270 ‫then we want the cheapest price possible. 21 00:00:59,270 --> 00:01:02,353 ‫And so, we're gonna sort also by price. 22 00:01:03,610 --> 00:01:06,060 ‫Let's quickly take a look at the results. 23 00:01:06,060 --> 00:01:08,163 ‫And, indeed, we get five tours here. 24 00:01:09,670 --> 00:01:12,560 ‫And, Postman does this scrolling again. 25 00:01:12,560 --> 00:01:14,517 ‫So, we have tours with 4.9, 26 00:01:15,951 --> 00:01:18,640 ‫4.9, 4.9 again, 27 00:01:18,640 --> 00:01:20,553 ‫4.8, and 4.7. 28 00:01:22,250 --> 00:01:27,060 ‫And so, these are actually our five best and cheapest tours. 29 00:01:27,060 --> 00:01:29,150 ‫If we said cheapest and best, well, 30 00:01:29,150 --> 00:01:32,270 ‫then maybe we would have to sort by price first 31 00:01:32,270 --> 00:01:34,580 ‫because some of them are not really cheap. 32 00:01:34,580 --> 00:01:36,320 ‫For example, this one. 33 00:01:36,320 --> 00:01:40,180 ‫But, we selected, first, the average. 34 00:01:40,180 --> 00:01:43,160 ‫And so, we sorted by the highest average first 35 00:01:43,160 --> 00:01:46,700 ‫and, only then in case of a tie, basically, 36 00:01:46,700 --> 00:01:47,900 ‫only then, by the price. 37 00:01:49,120 --> 00:01:51,340 ‫Now, let's say that this is a request 38 00:01:51,340 --> 00:01:53,350 ‫that is done all the time and we want 39 00:01:53,350 --> 00:01:55,060 ‫to provide a route that is simple 40 00:01:55,060 --> 00:01:57,453 ‫and easy to memorize for the user. 41 00:01:58,670 --> 00:02:02,110 ‫So, let's go to our app and try to implement that. 42 00:02:02,110 --> 00:02:06,330 ‫And, we're gonna start at their routes, so tour router. 43 00:02:06,330 --> 00:02:08,703 ‫And, we then need to create a new route. 44 00:02:09,550 --> 00:02:12,390 ‫And, let's do that here, right at the top. 45 00:02:12,390 --> 00:02:16,913 ‫So, router.route. 46 00:02:18,650 --> 00:02:21,370 ‫And so, how are we gonna call this route? 47 00:02:21,370 --> 00:02:25,293 ‫Well, let's say top-5-cheap. 48 00:02:26,590 --> 00:02:30,010 ‫So, quite a simple name, but it's gonna work. 49 00:02:30,010 --> 00:02:31,810 ‫And then, we actually only want 50 00:02:31,810 --> 00:02:34,103 ‫to get requests to this route. 51 00:02:35,170 --> 00:02:37,480 ‫And so, now it's time to think. 52 00:02:37,480 --> 00:02:41,370 ‫How are we gonna implement this functionality? 53 00:02:41,370 --> 00:02:43,530 ‫Well, in essence, what we want is 54 00:02:43,530 --> 00:02:47,273 ‫to actually still get all the tours just like here. 55 00:02:48,210 --> 00:02:51,070 ‫And so, let me go ahead and start by copying 56 00:02:51,070 --> 00:02:52,930 ‫and pasting that here. 57 00:02:52,930 --> 00:02:56,320 ‫So, we really still want to use this function here 58 00:02:56,320 --> 00:02:57,740 ‫because it doesn't really make sense 59 00:02:57,740 --> 00:03:00,900 ‫to rewrite all of the logic that is in there. 60 00:03:00,900 --> 00:03:04,010 ‫But, before we can call this route ender, 61 00:03:04,010 --> 00:03:06,690 ‫we basically want to prefill some of the fields 62 00:03:06,690 --> 00:03:07,833 ‫in the query string. 63 00:03:08,970 --> 00:03:10,340 ‫So, we already know 64 00:03:10,340 --> 00:03:13,590 ‫that our query string should look like this. 65 00:03:13,590 --> 00:03:16,370 ‫And, actually we can add some more stuff here. 66 00:03:16,370 --> 00:03:18,070 ‫But, in essence, our query string 67 00:03:18,070 --> 00:03:19,970 ‫has to look something like this. 68 00:03:19,970 --> 00:03:23,100 ‫And so, the solution is gonna be to run a middleware 69 00:03:23,100 --> 00:03:26,163 ‫before we actually run this getAllTours handler. 70 00:03:27,080 --> 00:03:28,760 ‫And so, that middleware function is then 71 00:03:28,760 --> 00:03:31,843 ‫gonna manipulate the query object that's coming in. 72 00:03:33,010 --> 00:03:35,210 ‫And so, this is yet another really nice example 73 00:03:35,210 --> 00:03:38,150 ‫of using middleware because you really need 74 00:03:38,150 --> 00:03:41,100 ‫to get familiar and used to this concept 75 00:03:41,100 --> 00:03:44,150 ‫of using middleware strategically in order 76 00:03:44,150 --> 00:03:47,123 ‫to change the request object as we need it. 77 00:03:48,690 --> 00:03:52,100 ‫So, let's add it here then. 78 00:03:52,100 --> 00:03:53,920 ‫So, tourController. 79 00:03:53,920 --> 00:03:55,150 ‫And then, the middleware function 80 00:03:55,150 --> 00:03:57,630 ‫that we're gonna create in a second, 81 00:03:57,630 --> 00:03:59,733 ‫which is gonna be called aliasTopTours. 82 00:04:05,060 --> 00:04:08,820 ‫So, let's copy that name, move to the tourController 83 00:04:08,820 --> 00:04:11,843 ‫and I'm gonna put it here at the very top. 84 00:04:14,100 --> 00:04:15,217 ‫So, exports., 85 00:04:17,370 --> 00:04:19,823 ‫then request, 86 00:04:21,650 --> 00:04:22,600 ‫response, 87 00:04:22,600 --> 00:04:24,030 ‫and what's the third argument 88 00:04:24,030 --> 00:04:27,180 ‫that we need in the middleware, remember? 89 00:04:27,180 --> 00:04:30,700 ‫And, I know the Express section is kind of far away already 90 00:04:30,700 --> 00:04:33,280 ‫at this point, but I hope you remember 91 00:04:33,280 --> 00:04:36,230 ‫that the third argument here needs to be next. 92 00:04:36,230 --> 00:04:38,970 ‫So, in order to call the next middleware 93 00:04:38,970 --> 00:04:40,520 ‫that's in the middleware stack. 94 00:04:45,600 --> 00:04:46,640 ‫Give it a save. 95 00:04:46,640 --> 00:04:49,203 ‫And so, this error there should disappear. 96 00:04:53,554 --> 00:04:55,950 ‫And so, let's do what we said we would do. 97 00:04:55,950 --> 00:04:58,870 ‫So, basically to manipulate the query object 98 00:04:58,870 --> 00:05:01,960 ‫so that when it reaches the getAllTours handler, 99 00:05:01,960 --> 00:05:03,423 ‫it's then already different. 100 00:05:04,270 --> 00:05:07,160 ‫So, let's first do that and then really 101 00:05:07,160 --> 00:05:08,783 ‫take a look at what happens. 102 00:05:10,010 --> 00:05:13,280 ‫So, remember, the limit is gonna be set to five. 103 00:05:13,280 --> 00:05:15,320 ‫And, remember that everything is strings here 104 00:05:15,320 --> 00:05:17,370 ‫and so I'm setting this also to a string. 105 00:05:19,350 --> 00:05:20,703 ‫Now, what else did we had? 106 00:05:21,580 --> 00:05:25,200 ‫So, we have this sort, so let's just copy this here 107 00:05:26,400 --> 00:05:30,623 ‫and say req.query.sort. 108 00:05:32,247 --> 00:05:35,050 ‫It should be this. 109 00:05:35,050 --> 00:05:39,230 ‫And then, we can actually also specify some fields 110 00:05:39,230 --> 00:05:42,560 ‫so that the user doesn't get all of the fields 111 00:05:42,560 --> 00:05:43,660 ‫that we have in there. 112 00:05:46,420 --> 00:05:49,033 ‫So, let's say that we only want the name, the price, 113 00:05:50,070 --> 00:05:52,973 ‫the ratings average, the summary, 114 00:05:54,570 --> 00:05:55,653 ‫and the difficulty. 115 00:05:58,650 --> 00:06:02,600 ‫Give it a save and now all we need is next, 116 00:06:02,600 --> 00:06:05,730 ‫otherwise this middleware will be stuck here forever 117 00:06:05,730 --> 00:06:07,043 ‫and cannot move on. 118 00:06:08,440 --> 00:06:10,420 ‫So, let's now figure out a bit better 119 00:06:10,420 --> 00:06:12,690 ‫what's actually gonna happen here. 120 00:06:12,690 --> 00:06:16,900 ‫So, as soon as someone hits the top-5-cheap route, 121 00:06:16,900 --> 00:06:17,733 ‫we will start. 122 00:06:17,733 --> 00:06:21,470 ‫The first middleware that's gonna be run is aliasTopTours. 123 00:06:21,470 --> 00:06:23,433 ‫So, the function that we just created. 124 00:06:25,420 --> 00:06:27,060 ‫So, what this is gonna do is 125 00:06:27,060 --> 00:06:30,070 ‫that it will set these properties of the query object 126 00:06:30,070 --> 00:06:32,490 ‫to these values that we specified here. 127 00:06:32,490 --> 00:06:35,800 ‫Basically prefilling parts of the query object 128 00:06:35,800 --> 00:06:39,453 ‫before we then reach the getAllTours handler. 129 00:06:40,720 --> 00:06:43,670 ‫And so, as soon as we then get to this function, 130 00:06:43,670 --> 00:06:46,080 ‫the query object is already prefilled, 131 00:06:46,080 --> 00:06:47,960 ‫even if the user didn't put any 132 00:06:47,960 --> 00:06:49,963 ‫of these parameters in the query string. 133 00:06:51,230 --> 00:06:52,170 ‫And so, in essence, 134 00:06:52,170 --> 00:06:55,137 ‫what we're doing here is prefilling the query string 135 00:06:55,137 --> 00:06:57,650 ‫for the user so that the user doesn't have 136 00:06:57,650 --> 00:06:59,083 ‫to do it on his own. 137 00:07:01,024 --> 00:07:03,683 ‫And so, let's now actually go ahead and try this. 138 00:07:04,780 --> 00:07:06,003 ‫So, I'm copying this. 139 00:07:09,380 --> 00:07:11,090 ‫And, here it's not tours. 140 00:07:11,090 --> 00:07:14,463 ‫It is top-5-tours. 141 00:07:16,710 --> 00:07:18,620 ‫Whoa, what's going on here? 142 00:07:18,620 --> 00:07:21,960 ‫For some reason, it doesn't find this route, 143 00:07:21,960 --> 00:07:23,360 ‫so let's go back. 144 00:07:23,360 --> 00:07:25,013 ‫So, top-5-tours. 145 00:07:26,140 --> 00:07:28,720 ‫And so, here in the route, ah, okay. 146 00:07:28,720 --> 00:07:30,690 ‫It's called top-5-cheap, 147 00:07:30,690 --> 00:07:32,093 ‫so my mistake here. 148 00:07:33,440 --> 00:07:35,780 ‫So, cheap, send it now, 149 00:07:35,780 --> 00:07:38,123 ‫and that's still not correct. 150 00:07:40,030 --> 00:07:41,110 ‫Ah, yeah. 151 00:07:41,110 --> 00:07:46,110 ‫Of course, I still have to put the tours here, of course. 152 00:07:46,140 --> 00:07:48,300 ‫So, we are in the tours resource 153 00:07:48,300 --> 00:07:50,210 ‫and the whole router is mounted 154 00:07:50,210 --> 00:07:53,670 ‫onto this tours route, remember that. 155 00:07:53,670 --> 00:07:55,430 ‫And so, it's in that tours, 156 00:07:55,430 --> 00:07:58,140 ‫that kind of mini application, remember that, 157 00:07:58,140 --> 00:08:00,723 ‫where I created this top-5-cheap route. 158 00:08:01,790 --> 00:08:03,470 ‫So, let's hope it works now. 159 00:08:03,470 --> 00:08:04,703 ‫And, indeed, it does. 160 00:08:07,350 --> 00:08:11,030 ‫So, that worked, that's fantastic. 161 00:08:11,030 --> 00:08:15,090 ‫Now, of course, we could do a lot more alias routes here, 162 00:08:15,090 --> 00:08:16,740 ‫but that's not really necessary. 163 00:08:16,740 --> 00:08:19,400 ‫I really just wanted to show you the concept, 164 00:08:19,400 --> 00:08:21,630 ‫show you that it can be a nice feature 165 00:08:21,630 --> 00:08:25,380 ‫to add to any API and also I wanted to, again, 166 00:08:25,380 --> 00:08:27,933 ‫show you the power of middlewares. 167 00:08:29,160 --> 00:08:30,950 ‫So, we're talking about Mongoose here, 168 00:08:30,950 --> 00:08:34,360 ‫but still, it's very important to keep getting familiar 169 00:08:34,360 --> 00:08:37,513 ‫with the Express concepts that we talked about before. 170 00:08:39,040 --> 00:08:42,120 ‫Anyway, we're now done with our API features. 171 00:08:42,120 --> 00:08:44,950 ‫In the next video, we're just gonna quickly refactor all 172 00:08:44,950 --> 00:08:48,690 ‫of this to make the entire code a bit more modular 173 00:08:48,690 --> 00:08:50,293 ‫and, of course, better.