1 00:00:00,673 --> 00:00:03,770 ‫Now, another extremely important feature 2 00:00:03,770 --> 00:00:07,200 ‫of a good API is to provide pagination. 3 00:00:07,200 --> 00:00:09,040 ‫So basically allowing the user 4 00:00:09,040 --> 00:00:12,660 ‫to only select a certain page of our results, 5 00:00:12,660 --> 00:00:15,373 ‫in case we have a lot of results. 6 00:00:17,140 --> 00:00:19,070 ‫So let's pretend that we have, for example, 7 00:00:19,070 --> 00:00:21,720 ‫1000 documents in a certain collection. 8 00:00:21,720 --> 00:00:25,160 ‫And we say that on each page we have 100 documents. 9 00:00:25,160 --> 00:00:28,230 ‫So that would mean that we'd have 10 pages, right? 10 00:00:28,230 --> 00:00:31,210 ‫So 10 times 100 is 1000. 11 00:00:31,210 --> 00:00:34,430 ‫And so based on that, how are we gonna implement pagination 12 00:00:34,430 --> 00:00:36,460 ‫using or query string? 13 00:00:36,460 --> 00:00:40,003 ‫Well, we will use the page and delimit fields. 14 00:00:41,460 --> 00:00:44,810 ‫So there will be a page field. 15 00:00:44,810 --> 00:00:47,230 ‫Let's say we want page two 16 00:00:47,230 --> 00:00:49,053 ‫and there will be a limit field. 17 00:00:50,760 --> 00:00:53,580 ‫And this limit here basically means the amount 18 00:00:53,580 --> 00:00:56,090 ‫of results that we want per page. 19 00:00:56,090 --> 00:00:59,090 ‫And that's actually setted here only to 10 20 00:00:59,090 --> 00:01:01,610 ‫and of course we have to correct this one here. 21 00:01:01,610 --> 00:01:03,910 ‫It's not a comma, but an and. 22 00:01:03,910 --> 00:01:06,690 ‫So page two and the limit 10. 23 00:01:06,690 --> 00:01:09,930 ‫Now going back to the example of 1000 results, 24 00:01:09,930 --> 00:01:13,380 ‫if the limit is 10, so only 10 results per page, 25 00:01:13,380 --> 00:01:15,670 ‫well then we're gonna have 100 pages 26 00:01:15,670 --> 00:01:18,800 ‫and in here we are then displaying page number 2 27 00:01:18,800 --> 00:01:20,780 ‫of these 100 pages. 28 00:01:20,780 --> 00:01:21,880 ‫Okay? 29 00:01:21,880 --> 00:01:26,600 ‫Now, we need now a way of implementing this using Mongoose. 30 00:01:26,600 --> 00:01:29,820 ‫So let's take a look at how we could do that 31 00:01:29,820 --> 00:01:31,653 ‫by going back to our code. 32 00:01:33,790 --> 00:01:35,313 ‫So feature number four, 33 00:01:36,970 --> 00:01:37,913 ‫Pagination. 34 00:01:39,530 --> 00:01:40,363 ‫All right, 35 00:01:40,363 --> 00:01:42,810 ‫And I will start by building an example query here 36 00:01:42,810 --> 00:01:44,880 ‫just like we did before. 37 00:01:44,880 --> 00:01:48,930 ‫So let's say that the query is equal query. 38 00:01:48,930 --> 00:01:51,200 ‫And now what kind of methods do we have 39 00:01:51,200 --> 00:01:53,270 ‫in order to implement pagination? 40 00:01:53,270 --> 00:01:55,770 ‫Well, the most useful one is skip 41 00:01:56,810 --> 00:01:59,570 ‫and I'm gonna explain what it does in a second, 42 00:01:59,570 --> 00:02:01,510 ‫so let's just put a random number here. 43 00:02:01,510 --> 00:02:03,913 ‫So skip and limit, 44 00:02:05,830 --> 00:02:07,070 ‫and let's put 10. 45 00:02:07,070 --> 00:02:10,150 ‫and so this limit here is actually exactly the same 46 00:02:10,150 --> 00:02:12,670 ‫as the limit that we defined in the query string. 47 00:02:12,670 --> 00:02:14,970 ‫So basically the amount of results 48 00:02:14,970 --> 00:02:16,810 ‫that we want in the query. 49 00:02:16,810 --> 00:02:20,710 ‫And then skip, that we have here, is the amount of results 50 00:02:20,710 --> 00:02:24,490 ‫that should be skipped before actually querying data. 51 00:02:24,490 --> 00:02:27,836 ‫All right, so again, this is just a placeholder here. 52 00:02:27,836 --> 00:02:30,573 ‫Let's go back to this example that we have here. 53 00:02:31,550 --> 00:02:34,193 ‫I'm just gonna copy this query string here. 54 00:02:36,279 --> 00:02:39,790 ‫so let's say that the user wants page number two 55 00:02:39,790 --> 00:02:42,600 ‫with 10 results per page. 56 00:02:42,600 --> 00:02:46,320 ‫That means that results one to 10 are on page one, 57 00:02:46,320 --> 00:02:49,090 ‫and 11 to 20 are on page 2. 58 00:02:49,090 --> 00:02:52,660 ‫Okay, and so what that means is that we want to skip 59 00:02:52,660 --> 00:02:55,720 ‫10 results before we actually start querying. 60 00:02:55,720 --> 00:02:56,750 ‫Okay. 61 00:02:56,750 --> 00:02:59,030 ‫So again, one to 10 62 00:03:00,840 --> 00:03:02,430 ‫are for page one 63 00:03:02,430 --> 00:03:04,770 ‫and then 11 to 20 64 00:03:07,230 --> 00:03:08,390 ‫are for page two, 65 00:03:08,390 --> 00:03:09,580 ‫and so on and so forth. 66 00:03:09,580 --> 00:03:13,303 ‫So 21 to 30 will be page three, 67 00:03:14,400 --> 00:03:15,920 ‫And so on and so forth. 68 00:03:15,920 --> 00:03:17,950 ‫And so we need to skip 10 results 69 00:03:17,950 --> 00:03:21,590 ‫in order to get to result number 11, right? 70 00:03:21,590 --> 00:03:26,590 ‫So to result number 11 which will the first one on page two. 71 00:03:26,640 --> 00:03:30,230 ‫Okay, and since it is page two that was requested, 72 00:03:30,230 --> 00:03:33,050 ‫well, again we need to skip 10 results 73 00:03:33,050 --> 00:03:35,380 ‫before we actually start page two. 74 00:03:35,380 --> 00:03:37,450 ‫Okay? Make sense? 75 00:03:37,450 --> 00:03:41,060 ‫And for example, if we requested page number three, 76 00:03:41,060 --> 00:03:43,380 ‫well then of course, 20 results would 77 00:03:43,380 --> 00:03:45,400 ‫first have to be skipped. 78 00:03:45,400 --> 00:03:46,840 ‫And so we will need some way 79 00:03:46,840 --> 00:03:49,680 ‫of calculating this skip value here. 80 00:03:49,680 --> 00:03:52,750 ‫So based basically on the page and the limit. 81 00:03:52,750 --> 00:03:55,700 ‫Now you might ask why I do not directly ask for the 82 00:03:55,700 --> 00:03:57,690 ‫skip value in the query string, 83 00:03:57,690 --> 00:04:00,370 ‫but that's because for the user this value here is 84 00:04:00,370 --> 00:04:01,980 ‫kind of abstract, okay? 85 00:04:01,980 --> 00:04:05,537 ‫It's way easier to simply say, "Well I want page number one, 86 00:04:05,537 --> 00:04:06,967 ‫"or I want page number five 87 00:04:06,967 --> 00:04:09,050 ‫"or I want like page number 10." 88 00:04:09,050 --> 00:04:12,520 ‫Okay, so for the user it's much easier 89 00:04:12,520 --> 00:04:14,983 ‫to not deal with skip values here 90 00:04:14,983 --> 00:04:18,100 ‫and all that stuff, the user wants to have it easy 91 00:04:18,100 --> 00:04:20,500 ‫and to just define a page. 92 00:04:20,500 --> 00:04:22,540 ‫Now before we can actually get started 93 00:04:22,540 --> 00:04:26,420 ‫calculating the skip value, we need to first get the page 94 00:04:26,420 --> 00:04:28,840 ‫and the limit from the query string 95 00:04:28,840 --> 00:04:31,700 ‫and we should also define some default values. 96 00:04:31,700 --> 00:04:33,550 ‫Okay, so that's basically 97 00:04:33,550 --> 00:04:35,910 ‫because we still want to have pagination 98 00:04:35,910 --> 00:04:38,560 ‫even if the user does not specify any page 99 00:04:38,560 --> 00:04:40,040 ‫or any limit. 100 00:04:40,040 --> 00:04:43,130 ‫Because for example let's say that we have a million results 101 00:04:43,130 --> 00:04:44,900 ‫in our database, 102 00:04:44,900 --> 00:04:47,750 ‫and then of course when the user does the request 103 00:04:47,750 --> 00:04:51,820 ‫we would not simply show all of these 10 million results. 104 00:04:51,820 --> 00:04:54,860 ‫That wouldn't be very user friendly, would it? 105 00:04:54,860 --> 00:04:58,610 ‫And so, I will define by default page number one 106 00:04:58,610 --> 00:05:01,500 ‫and a limit of let's say 100. 107 00:05:01,500 --> 00:05:05,100 ‫So that by default when a user requests all of the tours 108 00:05:05,100 --> 00:05:08,070 ‫in this example, then he only gets 100, 109 00:05:08,070 --> 00:05:10,273 ‫and not a million, all right? 110 00:05:11,470 --> 00:05:16,427 ‫So the page is of course request.query.page 111 00:05:18,290 --> 00:05:20,890 ‫and I'm now going to multiply it by one 112 00:05:20,890 --> 00:05:23,120 ‫which is just a nice trick to convert 113 00:05:23,120 --> 00:05:24,830 ‫a string to a number. 114 00:05:24,830 --> 00:05:28,370 ‫Okay, so maybe you noticed before that each time that we 115 00:05:28,370 --> 00:05:30,600 ‫actually put a number in a query string, 116 00:05:30,600 --> 00:05:33,730 ‫it will then be a string or a query object, 117 00:05:33,730 --> 00:05:37,410 ‫and so we need to fix that simply by multiplying by one. 118 00:05:37,410 --> 00:05:41,760 ‫Okay, and then by default, we want page number one. 119 00:05:41,760 --> 00:05:42,593 ‫All right? 120 00:05:42,593 --> 00:05:44,750 ‫And so this is a nice way in JavaScript 121 00:05:44,750 --> 00:05:47,690 ‫of basically defining default values. 122 00:05:47,690 --> 00:05:50,463 ‫And I'm sure you're familiar with that, right? 123 00:05:51,310 --> 00:05:56,310 ‫Anyway, the limit is on req.query.limit 124 00:05:58,370 --> 00:06:00,610 ‫times one again to convert it, 125 00:06:00,610 --> 00:06:04,300 ‫or the default of 100 that we just mentioned. 126 00:06:04,300 --> 00:06:08,240 ‫So ideally the user will only specify the page number 127 00:06:08,240 --> 00:06:09,570 ‫that he requests 128 00:06:09,570 --> 00:06:12,010 ‫and to not even bother with the page limit. 129 00:06:12,010 --> 00:06:14,370 ‫That's for more specific use cases. 130 00:06:14,370 --> 00:06:19,060 ‫Okay, and now all we need to do is to then define 131 00:06:19,060 --> 00:06:20,420 ‫so to calculate basically 132 00:06:21,450 --> 00:06:25,130 ‫that skip value that we just talked about here before. 133 00:06:25,130 --> 00:06:28,470 ‫And the best way of doing that is to go back to an example. 134 00:06:28,470 --> 00:06:31,940 ‫So again, let's say we are requesting page number three, 135 00:06:31,940 --> 00:06:33,610 ‫with the limit of 10. 136 00:06:33,610 --> 00:06:37,140 ‫and we see here for page number three the results are 137 00:06:37,140 --> 00:06:38,900 ‫from 21 to 30. 138 00:06:38,900 --> 00:06:42,340 ‫So it starts at result number 21, meaning that we need to 139 00:06:42,340 --> 00:06:44,110 ‫skip 20 results. 140 00:06:44,110 --> 00:06:47,140 ‫And 20 results is basically two times 10, 141 00:06:47,140 --> 00:06:49,510 ‫so two times this limit. 142 00:06:49,510 --> 00:06:52,700 ‫Okay, and from there we actually start getting a formula. 143 00:06:52,700 --> 00:06:57,140 ‫So two times ten is basically three minus one times 10. 144 00:06:57,140 --> 00:06:59,293 ‫And three is the page that we're on. 145 00:07:00,161 --> 00:07:01,760 ‫So that is our formula. 146 00:07:01,760 --> 00:07:03,780 ‫So page minus one 147 00:07:03,780 --> 00:07:05,693 ‫and so the previous page, basically, 148 00:07:06,690 --> 00:07:07,523 ‫times 149 00:07:08,750 --> 00:07:09,583 ‫the limit. 150 00:07:10,960 --> 00:07:13,733 ‫Okay, so I hope that made sense, 151 00:07:14,630 --> 00:07:17,273 ‫let's now replace these values here. 152 00:07:18,330 --> 00:07:19,163 ‫Skip 153 00:07:20,420 --> 00:07:22,193 ‫and limit of limit. 154 00:07:23,610 --> 00:07:24,550 ‫Okay? 155 00:07:24,550 --> 00:07:27,900 ‫So basically, this number here is all the results that 156 00:07:27,900 --> 00:07:31,230 ‫come before the page that we're actually requesting now. 157 00:07:31,230 --> 00:07:34,330 ‫So again, if we are requesting page number three 158 00:07:34,330 --> 00:07:37,280 ‫our results are gonna start at page number 21. 159 00:07:37,280 --> 00:07:40,020 ‫And so we wanna skip 20 results before that. 160 00:07:40,020 --> 00:07:41,490 ‫And so 20 results is 161 00:07:41,490 --> 00:07:44,683 ‫because we have 2 pages time 10 results on each, 162 00:07:45,940 --> 00:07:49,350 ‫Yeah, it's gonna be the page that we just requested. 163 00:07:49,350 --> 00:07:51,450 ‫So page here, minus one, 164 00:07:51,450 --> 00:07:54,260 ‫so the previous page times the number of results 165 00:07:54,260 --> 00:07:55,103 ‫on each page. 166 00:07:56,050 --> 00:07:58,870 ‫Okay, so that's the amount of documents that 167 00:07:58,870 --> 00:08:00,133 ‫are gonna be skipped. 168 00:08:01,772 --> 00:08:03,630 ‫Okay, so I hope that made sense. 169 00:08:03,630 --> 00:08:06,520 ‫Let's now go ahead and actually try this. 170 00:08:06,520 --> 00:08:09,460 ‫And since we only have so few results here 171 00:08:09,460 --> 00:08:12,093 ‫we need to test it with a really small limit. 172 00:08:13,260 --> 00:08:17,440 ‫So let's say that we only want three results per page, 173 00:08:17,440 --> 00:08:19,640 ‫and let's actually start on page number one. 174 00:08:22,280 --> 00:08:25,240 ‫So send it, and indeed now we only get 175 00:08:25,240 --> 00:08:27,463 ‫three results as you can see here. 176 00:08:28,880 --> 00:08:30,630 ‫So these three, let's see. 177 00:08:30,630 --> 00:08:32,030 ‫So The Forest Hiker, 178 00:08:32,030 --> 00:08:33,320 ‫The Sea Explorer, 179 00:08:33,320 --> 00:08:34,473 ‫and The City Wanderer. 180 00:08:35,550 --> 00:08:36,630 ‫Okay? 181 00:08:36,630 --> 00:08:38,900 ‫Let's try page number two, 182 00:08:38,900 --> 00:08:41,700 ‫and for some reason the postman keeps jumping around 183 00:08:41,700 --> 00:08:44,393 ‫each time that I change the URL. 184 00:08:45,900 --> 00:08:47,940 ‫Anyway, now we have The Park Camper, 185 00:08:47,940 --> 00:08:49,250 ‫The Snow Adventurer, 186 00:08:49,250 --> 00:08:50,810 ‫and The Sports Lover. 187 00:08:50,810 --> 00:08:52,920 ‫So you start seeing that we actually 188 00:08:52,920 --> 00:08:55,130 ‫now have different tours. 189 00:08:55,130 --> 00:08:55,963 ‫Okay? 190 00:08:55,963 --> 00:08:59,467 ‫And so we can kind of say that 191 00:08:59,467 --> 00:09:01,683 ‫our pagination here is already working. 192 00:09:03,550 --> 00:09:05,120 ‫Now the last page, 193 00:09:05,120 --> 00:09:07,630 ‫and we have now The Northern Lights, 194 00:09:07,630 --> 00:09:08,860 ‫The Wine Taster, 195 00:09:08,860 --> 00:09:10,780 ‫and The Star Gazer. 196 00:09:10,780 --> 00:09:12,100 ‫All right? 197 00:09:12,100 --> 00:09:16,380 ‫Now what if we try to go to page number four? 198 00:09:16,380 --> 00:09:19,020 ‫We already know that we only have nine tours, 199 00:09:19,020 --> 00:09:22,820 ‫and so on page number four there should be nothing. 200 00:09:22,820 --> 00:09:23,653 ‫Right? 201 00:09:23,653 --> 00:09:25,040 ‫So let's test that. 202 00:09:25,040 --> 00:09:27,600 ‫And indeed we get zero results. 203 00:09:27,600 --> 00:09:30,163 ‫But that is of course not ideal. 204 00:09:31,010 --> 00:09:34,130 ‫Okay, and so let's now go ahead and fix that 205 00:09:34,130 --> 00:09:37,207 ‫and basically kind of throw an error each time 206 00:09:37,207 --> 00:09:40,050 ‫the user selects a page that does not exist. 207 00:09:40,050 --> 00:09:42,320 ‫Because that's basically the situation here. 208 00:09:42,320 --> 00:09:45,600 ‫The user requested a page that simply does not exist. 209 00:09:45,600 --> 00:09:49,660 ‫We don't have enough results to have four pages 210 00:09:49,660 --> 00:09:50,733 ‫with three results. 211 00:09:53,120 --> 00:09:55,560 ‫Let's now do that, 212 00:09:55,560 --> 00:09:57,130 ‫and this will actually only happen 213 00:09:57,130 --> 00:10:00,020 ‫when there is a page on the query 214 00:10:00,020 --> 00:10:03,880 ‫and so let's actually create this if statement here. 215 00:10:03,880 --> 00:10:08,880 ‫So if request.query.page, 216 00:10:10,920 --> 00:10:13,960 ‫only in this case we will test if we are skipping more 217 00:10:13,960 --> 00:10:16,560 ‫tours than we actually have. 218 00:10:16,560 --> 00:10:18,610 ‫So let's get the amount of tours. 219 00:10:18,610 --> 00:10:22,830 ‫So number of tours is equal to, 220 00:10:22,830 --> 00:10:25,403 ‫and now we're actually going to learn a new method. 221 00:10:26,610 --> 00:10:28,780 ‫So a new method there is on the Tour model 222 00:10:28,780 --> 00:10:30,953 ‫which is called countDocuments. 223 00:10:34,600 --> 00:10:37,840 ‫Okay? And as the name says this is going to return 224 00:10:37,840 --> 00:10:40,533 ‫the number of documents, all right? 225 00:10:40,533 --> 00:10:42,600 ‫Actually it's gonna return a promise 226 00:10:42,600 --> 00:10:44,410 ‫but we then await the promise 227 00:10:44,410 --> 00:10:45,980 ‫and so it will then come back 228 00:10:45,980 --> 00:10:48,133 ‫with the result of the amount of tours. 229 00:10:49,064 --> 00:10:53,810 ‫Okay? And so if the number of documents that we skip 230 00:10:53,810 --> 00:10:57,550 ‫is greater than the number of documents that actually exists 231 00:10:57,550 --> 00:11:01,720 ‫well then that means that the page does not exist, alright? 232 00:11:01,720 --> 00:11:02,553 ‫That make sense? 233 00:11:04,720 --> 00:11:07,600 ‫So if skip is greater 234 00:11:07,600 --> 00:11:09,360 ‫than the number of tours, 235 00:11:09,360 --> 00:11:12,493 ‫and for now what I'm gonna do here is to throw a new error. 236 00:11:14,060 --> 00:11:14,893 ‫Okay? 237 00:11:14,893 --> 00:11:16,380 ‫So throw new error 238 00:11:18,490 --> 00:11:21,253 ‫this page does not exist. 239 00:11:23,260 --> 00:11:25,970 ‫Now why am I throwing an error here? 240 00:11:25,970 --> 00:11:29,120 ‫Well, simply because if I throw an error here 241 00:11:29,120 --> 00:11:32,560 ‫in the triblock which we are currently in, 242 00:11:32,560 --> 00:11:33,830 ‫it will then automatically 243 00:11:33,830 --> 00:11:37,180 ‫and immediately move on to the catch block, 244 00:11:37,180 --> 00:11:42,180 ‫and it will then send back this 404 kind of fail message. 245 00:11:42,610 --> 00:11:43,830 ‫Okay? 246 00:11:43,830 --> 00:11:46,470 ‫And so that's what we want for now. 247 00:11:46,470 --> 00:11:49,440 ‫Just keep in mind that we will implement much better 248 00:11:49,440 --> 00:11:51,510 ‫error handling a bit later in the course. 249 00:11:51,510 --> 00:11:55,010 ‫And actually right in the next section, okay? 250 00:11:55,010 --> 00:11:56,820 ‫But for now let's just keep it simple, 251 00:11:56,820 --> 00:11:58,390 ‫throw this error here 252 00:11:58,390 --> 00:12:00,880 ‫in case that we're trying to skip more documents 253 00:12:00,880 --> 00:12:01,980 ‫than we actually have. 254 00:12:02,830 --> 00:12:03,663 ‫Okay? 255 00:12:04,620 --> 00:12:08,070 ‫So this is the right case, let's send it here 256 00:12:08,070 --> 00:12:11,350 ‫and that's not the result that I expected 257 00:12:11,350 --> 00:12:13,150 ‫so let's go back 258 00:12:13,150 --> 00:12:15,590 ‫so right now our page is four 259 00:12:15,590 --> 00:12:17,670 ‫and the limit is three. 260 00:12:17,670 --> 00:12:21,730 ‫So the skip here would be three time three, so nine, okay? 261 00:12:21,730 --> 00:12:24,010 ‫And the number of tours is nine as well 262 00:12:24,010 --> 00:12:26,890 ‫and so skip is not greater than the number of tours 263 00:12:26,890 --> 00:12:28,840 ‫and therefore we don't get this error. 264 00:12:28,840 --> 00:12:32,910 ‫So what we need to do is to set it to greater or equal. 265 00:12:32,910 --> 00:12:35,423 ‫Okay, and so that should now work. 266 00:12:36,350 --> 00:12:38,610 ‫And that takes a long time, 267 00:12:38,610 --> 00:12:39,443 ‫and it did. 268 00:12:39,443 --> 00:12:42,290 ‫Now we get the fail status here 269 00:12:42,290 --> 00:12:43,470 ‫and a 404. 270 00:12:43,470 --> 00:12:44,303 ‫For some reason 271 00:12:45,170 --> 00:12:47,640 ‫this error is not showing up here 272 00:12:47,640 --> 00:12:49,113 ‫which it actually should. 273 00:12:50,360 --> 00:12:54,500 ‫But don't worry about that, that's not really important. 274 00:12:54,500 --> 00:12:58,010 ‫What matters is that it did actually enter our catch block, 275 00:12:58,010 --> 00:13:00,810 ‫and then send back this 404 response. 276 00:13:00,810 --> 00:13:03,490 ‫Everything else we're gonna implement a bit later. 277 00:13:03,490 --> 00:13:05,660 ‫Okay, and that's actually it. 278 00:13:05,660 --> 00:13:09,140 ‫So that's all the methods that we're gonna add to our query, 279 00:13:09,140 --> 00:13:12,727 ‫and so when we finally reach the next line of code here, 280 00:13:12,727 --> 00:13:14,740 ‫our query will then be awaited, 281 00:13:14,740 --> 00:13:17,440 ‫and return with the tours. 282 00:13:17,440 --> 00:13:21,365 ‫Okay, and at this point our query might actually look 283 00:13:21,365 --> 00:13:22,770 ‫something like 284 00:13:24,350 --> 00:13:26,600 ‫so something like this, something like 285 00:13:26,600 --> 00:13:27,850 ‫well what do we have here 286 00:13:28,860 --> 00:13:31,433 ‫we have sort, select, 287 00:13:32,630 --> 00:13:34,020 ‫so we might have sort, 288 00:13:34,020 --> 00:13:36,070 ‫and then some select there 289 00:13:36,070 --> 00:13:38,270 ‫we have also 290 00:13:38,270 --> 00:13:39,600 ‫skip 291 00:13:39,600 --> 00:13:41,803 ‫we have limit as well, 292 00:13:43,170 --> 00:13:46,270 ‫and so that's really kind of a big query. 293 00:13:46,270 --> 00:13:48,650 ‫And again, what allows us to that that is 294 00:13:48,650 --> 00:13:51,680 ‫that each of these methods here will always return 295 00:13:51,680 --> 00:13:54,610 ‫a new query that we can then chain on the next method 296 00:13:54,610 --> 00:13:55,570 ‫and the next method, 297 00:13:55,570 --> 00:13:59,330 ‫and the next method until we finally await the query 298 00:13:59,330 --> 00:14:02,890 ‫so that it can actually give us our documents. 299 00:14:02,890 --> 00:14:06,110 ‫Okay, so let's get rid of all these comments 300 00:14:06,110 --> 00:14:08,500 ‫and yeah, that's it for now. 301 00:14:08,500 --> 00:14:10,850 ‫For these features we're just gonna add one more 302 00:14:10,850 --> 00:14:12,220 ‫in the next lecture, 303 00:14:12,220 --> 00:14:14,570 ‫but that one is gonna be a bit different than these. 304 00:14:14,570 --> 00:14:18,090 ‫It's not gonna use one of these query methods, all right? 305 00:14:18,090 --> 00:14:20,470 ‫So I hope that over the last couple of lectures 306 00:14:20,470 --> 00:14:22,230 ‫you really learned the ins and outs 307 00:14:22,230 --> 00:14:24,530 ‫of querying data with Mongoose. 308 00:14:24,530 --> 00:14:27,540 ‫So of course, all of these methods that we used are not 309 00:14:27,540 --> 00:14:30,640 ‫only useful for these features that we implemented here. 310 00:14:30,640 --> 00:14:32,760 ‫You can really create all kinds of querys 311 00:14:32,760 --> 00:14:36,200 ‫that you can imagine for all kinds of applications. 312 00:14:36,200 --> 00:14:38,890 ‫So I showed you all the techniques here in this context 313 00:14:38,890 --> 00:14:41,090 ‫of these different API features, 314 00:14:41,090 --> 00:14:43,000 ‫but of course you're gonna be able to use them 315 00:14:43,000 --> 00:14:46,520 ‫all over your applications in the future, okay? 316 00:14:46,520 --> 00:14:48,780 ‫So I hope that was fun for you 317 00:14:48,780 --> 00:14:53,510 ‫and if it was, then let's move on now right to the next one. 318 00:14:53,510 --> 00:14:54,343 ‫See you!