1
00:00:01,090 --> 00:00:03,630
‫Let's now implement result sorting.

2
00:00:03,630 --> 00:00:07,000
‫In order to enable our users to sort result

3
00:00:07,000 --> 00:00:08,763
‫based on a certain field.

4
00:00:10,180 --> 00:00:14,033
‫So, let's now take a look at all our results here for now.

5
00:00:14,970 --> 00:00:17,930
‫All right, and so let's say that we actually want

6
00:00:17,930 --> 00:00:21,129
‫to sort these results, let's say by price.

7
00:00:21,129 --> 00:00:24,560
‫Okay, so starting with the lowest price and then moving up

8
00:00:24,560 --> 00:00:27,300
‫all the way to the highest price.

9
00:00:27,300 --> 00:00:29,462
‫All right, so we have all kinds of prices.

10
00:00:29,462 --> 00:00:33,830
‫397, 497, 1197, 1497, 997.

11
00:00:36,330 --> 00:00:38,950
‫We have even almost 3,000 here.

12
00:00:38,950 --> 00:00:42,570
‫Then 1497 and so they're not really in order,

13
00:00:42,570 --> 00:00:47,450
‫and so let's allow the user to basically sort these results

14
00:00:47,450 --> 00:00:50,963
‫based on a field that can be passed using the query string.

15
00:00:53,690 --> 00:00:58,663
‫So let's say we want to sort by price.

16
00:00:59,860 --> 00:01:00,890
‫All right.

17
00:01:00,890 --> 00:01:03,480
‫So if we run this now, of course, nothing will happen,

18
00:01:03,480 --> 00:01:05,860
‫it will still show the exact same nine results

19
00:01:05,860 --> 00:01:09,900
‫and in the same order, because before in the last lecture,

20
00:01:09,900 --> 00:01:13,710
‫we filtered out basically this sort field.

21
00:01:13,710 --> 00:01:14,543
‫Right?

22
00:01:14,543 --> 00:01:16,883
‫And so let's now actually go ahead and use it.

23
00:01:18,020 --> 00:01:19,120
‫All right?

24
00:01:19,120 --> 00:01:22,650
‫So, remember here how we created the query object

25
00:01:22,650 --> 00:01:25,430
‫and then excluded the sort field here,

26
00:01:25,430 --> 00:01:28,840
‫so that it didn't pollute our filtering, right?

27
00:01:28,840 --> 00:01:33,073
‫But now we actually need it and so let's now use it.

28
00:01:34,150 --> 00:01:38,040
‫So, the third feature here is sorting.

29
00:01:38,040 --> 00:01:39,790
‫Or actually, well that's the second one,

30
00:01:39,790 --> 00:01:43,977
‫so let's just call this one 1A and 1B.

31
00:01:43,977 --> 00:01:44,963
‫All right?

32
00:01:46,400 --> 00:01:51,400
‫So, let's say that if there actually is a sort,

33
00:01:53,750 --> 00:01:56,980
‫sort req.query.sort.

34
00:01:56,980 --> 00:01:58,913
‫Okay, and you see it down here.

35
00:01:59,750 --> 00:02:04,210
‫Now it's gone because of this error here, but anyway.

36
00:02:04,210 --> 00:02:06,427
‫From our last request we got, of course,

37
00:02:06,427 --> 00:02:09,290
‫there's a query object here and so in there

38
00:02:09,290 --> 00:02:12,840
‫we had the sort property, all right?

39
00:02:12,840 --> 00:02:15,010
‫And if there is a sort property,

40
00:02:15,010 --> 00:02:16,780
‫well, that means that then

41
00:02:16,780 --> 00:02:20,935
‫we want to actually sort the results based on the value.

42
00:02:20,935 --> 00:02:23,400
‫Now one quick thing that we need to do,

43
00:02:23,400 --> 00:02:26,040
‫is to change this query of variable here from

44
00:02:26,040 --> 00:02:29,630
‫a constant to a normal variable.

45
00:02:29,630 --> 00:02:31,420
‫So let, okay?

46
00:02:31,420 --> 00:02:34,284
‫'Cause now we actually want to chain something

47
00:02:34,284 --> 00:02:36,000
‫to this query.

48
00:02:36,000 --> 00:02:39,600
‫So, the new query will be query.sort.

49
00:02:42,410 --> 00:02:46,580
‫And we want to sort it by req.query.sort.

50
00:02:48,607 --> 00:02:52,060
‫All right, 'cause that will be the value of the field,

51
00:02:52,060 --> 00:02:53,760
‫so in this case price,

52
00:02:53,760 --> 00:02:56,270
‫and Mongoose will then automatically sort the result

53
00:02:56,270 --> 00:02:57,910
‫based on the price.

54
00:02:57,910 --> 00:02:59,640
‫And now in case you're wondering,

55
00:02:59,640 --> 00:03:02,600
‫why it works this way, so why we did this here,

56
00:03:02,600 --> 00:03:05,910
‫just remember what we talked about over the last lectures.

57
00:03:05,910 --> 00:03:08,910
‫So, remember how this tour.find here

58
00:03:08,910 --> 00:03:11,030
‫is gonna return a query, right?

59
00:03:11,030 --> 00:03:13,320
‫And so we stored that query object here

60
00:03:13,320 --> 00:03:15,320
‫in this variable, so that later on

61
00:03:15,320 --> 00:03:17,800
‫we can keep chaining more methods to it.

62
00:03:17,800 --> 00:03:19,990
‫So more of these methods that are available

63
00:03:19,990 --> 00:03:23,150
‫on all documents created through the query class.

64
00:03:23,150 --> 00:03:24,780
‫Okay, remember that?

65
00:03:24,780 --> 00:03:27,620
‫I think we talked about that in depth two lectures ago.

66
00:03:27,620 --> 00:03:31,180
‫So in case this is still a bit confusing to you,

67
00:03:31,180 --> 00:03:32,560
‫then just go back there

68
00:03:32,560 --> 00:03:36,450
‫or you can also take a look at the documentation, all right?

69
00:03:36,450 --> 00:03:40,840
‫Now let's actually test this out.

70
00:03:40,840 --> 00:03:43,500
‫So sort is still set to price.

71
00:03:43,500 --> 00:03:45,402
‫So I'll send it now.

72
00:03:45,402 --> 00:03:48,210
‫Let's take a look at the result.

73
00:03:48,210 --> 00:03:50,250
‫And indeed we start with the lowest price,

74
00:03:50,250 --> 00:03:52,270
‫but I think we already had that before.

75
00:03:52,270 --> 00:03:57,270
‫So we start with 397, then 497, then 997, 1197,

76
00:03:59,310 --> 00:04:04,020
‫1497, and you see that the prices actually keep increasing.

77
00:04:04,020 --> 00:04:07,523
‫So 1997, 2997.

78
00:04:08,570 --> 00:04:11,163
‫And so yeah, indeed, they are now sorted.

79
00:04:12,830 --> 00:04:13,663
‫Okay?

80
00:04:13,663 --> 00:04:16,610
‫So we sorted them by the price in an ascending order.

81
00:04:16,610 --> 00:04:19,430
‫But we can also sort them in a descending order.

82
00:04:19,430 --> 00:04:20,810
‫That's very simple.

83
00:04:20,810 --> 00:04:24,090
‫All we have to do is to set as the minus here.

84
00:04:24,090 --> 00:04:27,200
‫So, minus price and Mongoose will then automatically

85
00:04:27,200 --> 00:04:29,040
‫sort them in the other order.

86
00:04:29,040 --> 00:04:31,221
‫So, in the descending order.

87
00:04:31,221 --> 00:04:34,220
‫So let's test out that one as well.

88
00:04:34,220 --> 00:04:36,750
‫And so now we should start with, yeah exactly,

89
00:04:36,750 --> 00:04:38,150
‫with this one.

90
00:04:38,150 --> 00:04:40,190
‫So, the first one is now the highest

91
00:04:40,190 --> 00:04:43,960
‫and the last one is the 397 one.

92
00:04:43,960 --> 00:04:44,930
‫Cool.

93
00:04:44,930 --> 00:04:48,030
‫But we can actually take it one step further,

94
00:04:48,030 --> 00:04:51,500
‫because we have many cases here which have the same price.

95
00:04:51,500 --> 00:04:54,390
‫But how are these results with the same price then

96
00:04:54,390 --> 00:04:56,190
‫ordered within them?

97
00:04:56,190 --> 00:04:58,468
‫So let's say we have this one with this price

98
00:04:58,468 --> 00:05:00,700
‫and then this one with the same price.

99
00:05:00,700 --> 00:05:05,330
‫So why does this one appear before the second one?

100
00:05:05,330 --> 00:05:08,050
‫The same thing with this one here maybe,

101
00:05:08,050 --> 00:05:09,720
‫oh actually not.

102
00:05:09,720 --> 00:05:12,496
‫So this one is just the only one with 1997.

103
00:05:12,496 --> 00:05:16,650
‫But then here again we have these two with the same price.

104
00:05:16,650 --> 00:05:21,563
‫We have, okay, they are all different.

105
00:05:23,360 --> 00:05:25,150
‫Okay, these are all different.

106
00:05:25,150 --> 00:05:27,610
‫But we want to rank them, basically,

107
00:05:27,610 --> 00:05:29,900
‫according to a second criteria.

108
00:05:29,900 --> 00:05:31,790
‫So in case there is a tie,

109
00:05:31,790 --> 00:05:33,570
‫then we want to have a second field

110
00:05:33,570 --> 00:05:36,550
‫by which we can then sort where the first one is the same.

111
00:05:36,550 --> 00:05:38,230
‫So in this case the price.

112
00:05:38,230 --> 00:05:40,500
‫So in Mongoose that's quite easy,

113
00:05:40,500 --> 00:05:43,400
‫and let me show that to you here as a comment for example.

114
00:05:44,450 --> 00:05:47,510
‫So in Mongoose we would just say sort

115
00:05:49,650 --> 00:05:52,980
‫and then right now we have the price,

116
00:05:52,980 --> 00:05:54,430
‫so we have it just like this,

117
00:05:54,430 --> 00:05:56,340
‫but then in Mongoose all we have to do

118
00:05:56,340 --> 00:05:59,690
‫is to add another field name to the string.

119
00:05:59,690 --> 00:06:02,563
‫So for example, rating average.

120
00:06:03,451 --> 00:06:06,130
‫Or I think it's ratings.

121
00:06:06,130 --> 00:06:10,460
‫Okay, and so we now want to pass this field here as well

122
00:06:10,460 --> 00:06:11,363
‫to our sort.

123
00:06:12,640 --> 00:06:13,473
‫Okay?

124
00:06:13,473 --> 00:06:15,900
‫Now we cannot leave a space here in the URL

125
00:06:15,900 --> 00:06:17,933
‫and so instead we're gonna add a comma.

126
00:06:18,880 --> 00:06:19,713
‫Okay?

127
00:06:19,713 --> 00:06:22,080
‫So we want to sort first by price

128
00:06:22,080 --> 00:06:25,862
‫and then as a second criteria, also by ratings average.

129
00:06:25,862 --> 00:06:26,757
‫Okay?

130
00:06:26,757 --> 00:06:28,440
‫And so now all we need to do

131
00:06:28,440 --> 00:06:33,060
‫is to basically replace this comma here with a space.

132
00:06:33,060 --> 00:06:33,893
‫All right?

133
00:06:33,893 --> 00:06:36,004
‫And of course, we could have even more fields

134
00:06:36,004 --> 00:06:38,460
‫by which we sort.

135
00:06:38,460 --> 00:06:39,293
‫Okay?

136
00:06:39,293 --> 00:06:40,900
‫But for now let's just leave it like this

137
00:06:40,900 --> 00:06:43,813
‫and implement it very quickly in our code.

138
00:06:44,820 --> 00:06:45,810
‫All right?

139
00:06:45,810 --> 00:06:48,543
‫And actually let me create a new variable here.

140
00:06:49,870 --> 00:06:51,303
‫Let's call it sort by.

141
00:06:53,014 --> 00:06:57,410
‫And so we have req.query.sort

142
00:06:57,410 --> 00:07:01,020
‫and what we're gonna do is to now split it by the comma.

143
00:07:01,020 --> 00:07:05,867
‫So split the string by the comma,

144
00:07:05,867 --> 00:07:08,220
‫and so this will then return an array of all the strings,

145
00:07:08,220 --> 00:07:09,720
‫so all the field names,

146
00:07:09,720 --> 00:07:13,060
‫and then all we have to do is to put it back together

147
00:07:13,060 --> 00:07:17,453
‫using join, and as the join string we use a space.

148
00:07:18,490 --> 00:07:19,980
‫All right?

149
00:07:19,980 --> 00:07:23,223
‫And so just to make sure that it's correct.

150
00:07:24,280 --> 00:07:29,280
‫Console.log, sort by, and then of course here

151
00:07:29,363 --> 00:07:32,423
‫we want to use that sort by variable.

152
00:07:34,280 --> 00:07:35,240
‫Okay?

153
00:07:35,240 --> 00:07:36,690
‫So let's take a look at that.

154
00:07:40,450 --> 00:07:41,633
‫And.

155
00:07:43,350 --> 00:07:48,350
‫So 4.7 here, and the other one also has 4.7, all right?

156
00:07:48,990 --> 00:07:52,130
‫And so let's actually go ahead and use our API

157
00:07:52,130 --> 00:07:54,360
‫to change this ratings average here.

158
00:07:54,360 --> 00:07:55,193
‫Okay?

159
00:07:55,193 --> 00:07:56,740
‫So just as a fun experiment,

160
00:07:56,740 --> 00:08:00,483
‫let's copy this ID here, then update tour,

161
00:08:02,060 --> 00:08:04,440
‫and so let's come here to the body,

162
00:08:04,440 --> 00:08:08,367
‫and so I want to update ratings average to 4.9.

163
00:08:13,465 --> 00:08:14,380
‫Okay?

164
00:08:14,380 --> 00:08:18,513
‫Let's send that, and indeed, you see that it got updated.

165
00:08:21,120 --> 00:08:22,940
‫And so now let's change that again,

166
00:08:22,940 --> 00:08:24,700
‫or let's try that again actually.

167
00:08:24,700 --> 00:08:27,534
‫And so now you see the first one still has 4.7

168
00:08:27,534 --> 00:08:30,510
‫and this one here now has 4.9.

169
00:08:30,510 --> 00:08:34,476
‫And so they are now ordered with an ascending rating.

170
00:08:34,476 --> 00:08:35,600
‫Right?

171
00:08:35,600 --> 00:08:38,335
‫And of course, we could put a minus here

172
00:08:38,335 --> 00:08:41,653
‫and so then they should change positions,

173
00:08:41,653 --> 00:08:45,970
‫meaning that the one with 4.9 should appear first.

174
00:08:45,970 --> 00:08:47,960
‫Let's try that as well.

175
00:08:47,960 --> 00:08:50,590
‫And yeah, indeed.

176
00:08:50,590 --> 00:08:53,010
‫So now this one, the sports lover tour,

177
00:08:53,010 --> 00:08:55,230
‫is the one that appears first.

178
00:08:55,230 --> 00:08:56,710
‫All right, great.

179
00:08:56,710 --> 00:08:58,800
‫So it looks like it's working.

180
00:08:58,800 --> 00:09:01,270
‫Let's a take a look at our results here.

181
00:09:01,270 --> 00:09:02,670
‫And yeah, indeed.

182
00:09:02,670 --> 00:09:04,970
‫And let's just take a look at what we logged here

183
00:09:04,970 --> 00:09:06,190
‫at the console.

184
00:09:06,190 --> 00:09:10,453
‫And so, yeah, this is our sort by variable, which yeah.

185
00:09:11,790 --> 00:09:14,718
‫Which kind of looks similar to what we have here.

186
00:09:14,718 --> 00:09:17,560
‫And so that was the goal of creating this variable.

187
00:09:17,560 --> 00:09:19,410
‫Great, so that's now working.

188
00:09:19,410 --> 00:09:23,263
‫Let's get rid of this console and this one here as well.

189
00:09:24,430 --> 00:09:26,180
‫And all right.

190
00:09:26,180 --> 00:09:27,140
‫And just to finish here,

191
00:09:27,140 --> 00:09:29,910
‫let's actually add a default one.

192
00:09:29,910 --> 00:09:33,565
‫And we do that by simply adding an else block here.

193
00:09:33,565 --> 00:09:36,580
‫So in case that the user does not specify

194
00:09:36,580 --> 00:09:39,770
‫any sort field in the URL query string,

195
00:09:39,770 --> 00:09:42,583
‫we're still gonna add a sort to the query.

196
00:09:43,850 --> 00:09:47,300
‫So query.sort and we will then sort

197
00:09:47,300 --> 00:09:49,990
‫by the created add field, all right?

198
00:09:49,990 --> 00:09:51,830
‫And actually in a descending order,

199
00:09:51,830 --> 00:09:54,330
‫so that the newest ones appear first.

200
00:09:54,330 --> 00:09:59,070
‫So minus created at.

201
00:09:59,070 --> 00:10:00,050
‫All right?

202
00:10:00,050 --> 00:10:01,730
‫Give this a save.

203
00:10:01,730 --> 00:10:05,240
‫And so yeah, I think like this, we're done.

204
00:10:05,240 --> 00:10:09,140
‫Let's just turn off this option here as well.

205
00:10:09,140 --> 00:10:12,503
‫And so now we just are back to our regular URL

206
00:10:13,390 --> 00:10:15,100
‫without any query strings.

207
00:10:15,100 --> 00:10:16,570
‫And so let's take a look

208
00:10:16,570 --> 00:10:19,780
‫if this is now actually ordered by the created at.

209
00:10:19,780 --> 00:10:22,713
‫So this one here ends in 59 seconds and 30.

210
00:10:23,730 --> 00:10:25,230
‫5930 as well.

211
00:10:25,230 --> 00:10:27,363
‫And yeah.

212
00:10:27,363 --> 00:10:29,670
‫So they were all created at the exact same moment,

213
00:10:29,670 --> 00:10:32,990
‫because we imported them all at the same time.

214
00:10:32,990 --> 00:10:33,823
‫All right?

215
00:10:33,823 --> 00:10:36,250
‫And so in this case, we cannot really see

216
00:10:36,250 --> 00:10:38,920
‫the effect of this piece of code

217
00:10:38,920 --> 00:10:41,810
‫that we just added here, but in case these documents

218
00:10:41,810 --> 00:10:44,130
‫were added at different times, then they would now

219
00:10:44,130 --> 00:10:46,901
‫be ordered by the date they were created.

220
00:10:46,901 --> 00:10:48,430
‫All right?

221
00:10:48,430 --> 00:10:50,450
‫So that's it for sorting.

222
00:10:50,450 --> 00:10:53,320
‫Next up, we're gonna talk about limiting the fields

223
00:10:53,320 --> 00:10:54,763
‫that we want in our results.