0
1
00:00:00,820 --> 00:00:08,230
Now that we've seen how we can create new documents and new collections into our database using Mongoose
1

2
00:00:08,320 --> 00:00:09,390
and MongoDB,
2

3
00:00:09,820 --> 00:00:13,690
the next thing to look at is how do we read from our database?
3

4
00:00:13,840 --> 00:00:14,790
How do we perform
4

5
00:00:14,800 --> 00:00:18,880
what is the equivalent of find that we saw in the Mongo shell?
5

6
00:00:19,300 --> 00:00:22,770
Well it's also pretty simple and it's a lot simpler than this.
6

7
00:00:22,990 --> 00:00:29,430
All we have to do is tap into our fruit model which you can effectively see as kind of your collection
7

8
00:00:29,440 --> 00:00:30,030
right?
8

9
00:00:30,040 --> 00:00:35,520
This is going to be all about fruits and we're going to call the Find function on it.
9

10
00:00:35,730 --> 00:00:43,540
Now this find function can accept a callback. And that callback has two parameters.
10

11
00:00:43,720 --> 00:00:48,540
The first one is error and the second one is whatever it finds back.
11

12
00:00:48,700 --> 00:00:54,160
So we can call it anything we want. But in this case given that we're searching through our fruits collection
12

13
00:00:54,220 --> 00:00:59,560
to find everything because we're not filtering, we're not querying anything, then what we'll get back
13

14
00:00:59,590 --> 00:01:04,030
is all of our fruits right? Inside this callback
14

15
00:01:04,030 --> 00:01:12,220
we can check to see if there was an error and if so we'll log the error. But otherwise we'll simply just
15

16
00:01:12,310 --> 00:01:18,510
log the fruits that we found from the find method.
16

17
00:01:18,580 --> 00:01:21,260
So the full syntax looks a bit like this.
17

18
00:01:21,340 --> 00:01:27,730
We tap into our fruits collection through the fruit model, we call the find function on it and then when
18

19
00:01:27,730 --> 00:01:34,150
that's completed a callback gets triggered and we have the possibility of having an error if anything
19

20
00:01:34,150 --> 00:01:39,830
went wrong with finding our fruits but otherwise we would get some results back which we've called fruit.
20

21
00:01:39,970 --> 00:01:47,180
And if there were no errors then we simply just log all the results that we get back from our find function.
21

22
00:01:47,200 --> 00:01:54,250
Now just before we run on app.js, unless you want to insert another three of these same fruits into
22

23
00:01:54,270 --> 00:02:00,820
our fruits collection, it's a good idea to comment out this part where we call the insertMany function.
23

24
00:02:01,270 --> 00:02:06,850
That way we won't end up with the same fruits inserted into our collection many many times or at least
24

25
00:02:06,910 --> 00:02:09,480
every single time we run app.js.
25

26
00:02:09,700 --> 00:02:15,010
So let's head over to our hyper terminal and let's hit CONTROL + C to exit.
26

27
00:02:15,010 --> 00:02:17,900
And again run on node app.js.
27

28
00:02:17,950 --> 00:02:24,870
So now you can see that it's read into our fruits database, which is what we asked it to do here,
28

29
00:02:25,090 --> 00:02:28,730
and then it's performed that find function onto it.
29

30
00:02:28,930 --> 00:02:34,270
And because there were no errors then it's logged all of the results that it found in that collection
30

31
00:02:34,450 --> 00:02:41,350
which is basically all of our fruits. And these aren't living Javascript objects and they're all contained
31

32
00:02:41,380 --> 00:02:43,300
inside an array.
32

33
00:02:43,300 --> 00:02:49,870
So everything that we've learned so far about arrays and Javascript objects now applies to our data
33

34
00:02:49,960 --> 00:02:56,470
in our database which means that we can tap into its properties by using the dot notation or pass it
34

35
00:02:56,470 --> 00:03:00,240
around in two different methods and we can work with it in our app.
35

36
00:03:00,250 --> 00:03:00,910
js.
36

37
00:03:03,720 --> 00:03:11,370
So given that you know that this thing we get back called fruits is an array of fruit objects each
37

38
00:03:11,370 --> 00:03:15,050
with their own properties such as name and rating
38

39
00:03:15,060 --> 00:03:18,870
and each of those properties have associated values,
39

40
00:03:19,140 --> 00:03:21,740
then here's a challenge for you.
40

41
00:03:22,050 --> 00:03:28,300
I want you to use the for each loop that we learnt about previously in the EJS challenge module
41

42
00:03:28,590 --> 00:03:35,110
and I want you to loop through the array of fruits and only log their names,
42

43
00:03:35,160 --> 00:03:37,030
so the names of the fruit.
43

44
00:03:37,110 --> 00:03:44,430
So if you were successful then inside the console here you should be able to see just apple, kiwi, orange
44

45
00:03:44,460 --> 00:03:47,150
banana without the rest of this data.
45

46
00:03:48,330 --> 00:03:51,450
Pause the video now and try to complete the challenge.
46

47
00:03:54,820 --> 00:04:01,210
Okay. So we know that inside here we have access to an array called fruits.
47

48
00:04:01,210 --> 00:04:04,810
How can we loop through just any other array?
48

49
00:04:04,810 --> 00:04:12,040
Well, we would tap into the array, fruits, and then we would call the forEach method onto it.
49

50
00:04:12,040 --> 00:04:15,710
And this forEach method accepts a callback
50

51
00:04:15,940 --> 00:04:22,960
and inside that callback we have a single parameter which is going to be each individual object inside
51

52
00:04:23,020 --> 00:04:23,760
the array.
52

53
00:04:23,950 --> 00:04:25,030
So when we loop through it
53

54
00:04:25,030 --> 00:04:28,470
we're going to pick out each and every fruit out of the array.
54

55
00:04:28,660 --> 00:04:30,850
So we'll just call it fruit
55

56
00:04:30,880 --> 00:04:33,470
in that case, the singular form.
56

57
00:04:33,730 --> 00:04:37,690
And now inside our callback we get two console log
57

58
00:04:37,690 --> 00:04:46,090
each fruit and we get to tap into its name property through the use of the dot name.
58

59
00:04:46,090 --> 00:04:53,410
Now through this little very short bit of code, we loop through our fruits array that we got back from
59

60
00:04:53,410 --> 00:04:54,450
our database
60

61
00:04:54,670 --> 00:05:00,520
and for each fruit, we will console log the fruit's name.
61

62
00:05:00,550 --> 00:05:03,490
There's a lot of singular and plurals going on around here.
62

63
00:05:03,520 --> 00:05:06,790
So you have to make sure you know which one you're using when.
63

64
00:05:07,000 --> 00:05:09,530
Let's go ahead and delete that previous console log
64

65
00:05:09,550 --> 00:05:12,080
where we logged the entire fruits array.
65

66
00:05:12,310 --> 00:05:16,990
And let's run our app.js to see it in action.
66

67
00:05:17,140 --> 00:05:23,330
So let's again close our database connection with CONTROL + C and then run node app.
67

68
00:05:23,360 --> 00:05:23,960
js.
68

69
00:05:24,160 --> 00:05:32,250
And you can see we now loop through our fruits array and we print out each and every name property.
69

70
00:05:32,260 --> 00:05:35,290
So we end up with apple, kiwi, orange, banana.
70

71
00:05:35,690 --> 00:05:42,460
And so you can imagine that inside our app.js now we have the entire flexibility of working with Javascript
71

72
00:05:42,460 --> 00:05:49,180
arrays and Javascript native objects to tap into their properties, to pass them around into functions
72

73
00:05:49,780 --> 00:05:51,850
and use them wherever we need them.
73

74
00:05:53,820 --> 00:06:00,800
Now at the moment, you might have noticed that we have to keep closing our database connection with CONTROL +
74

75
00:06:00,790 --> 00:06:03,750
C. This is because inside our app.
75

76
00:06:03,770 --> 00:06:09,860
js, we're not closing that database connection. We're keeping it open at the end.
76

77
00:06:09,960 --> 00:06:13,980
We open that connection when we call mongoose.connect.
77

78
00:06:14,100 --> 00:06:18,190
But it's also good practice to close the connection to our database
78

79
00:06:18,240 --> 00:06:26,050
once we're done with it in our app. Inside the method where we perform the last action we want to do
79

80
00:06:26,050 --> 00:06:31,800
with our database which in this case is finding fruits inside the database,
80

81
00:06:31,840 --> 00:06:40,090
then once it's completed and the callback is being called and we have no errors then what we can do
81

82
00:06:40,180 --> 00:06:51,690
is we can say "mongoose.connection.close" so we call the close method on our mongoose collection.
82

83
00:06:51,930 --> 00:06:54,630
And now if I rerun my app
83

84
00:06:54,720 --> 00:07:01,240
so for the last time use CONTROL + C to exit out of our database connection, run node app.
84

85
00:07:01,270 --> 00:07:06,050
js and you can see that once it's done performing the task I asked it to
85

86
00:07:06,300 --> 00:07:15,450
which is to find all of the fruits inside the fruit collection then log its names through this forEach
86

87
00:07:15,450 --> 00:07:20,210
loop then it's close the connection and I don't have to use CONTROL + C anymore.
87

88
00:07:20,340 --> 00:07:27,260
So this is good practice whenever you're working with MongoDB databases and Mongoose. Close the connection
88

89
00:07:27,270 --> 00:07:27,810
once you've done.