1 00:00:05,990 --> 00:00:07,100 Welcome back. 2 00:00:07,130 --> 00:00:11,060 In this video, let's see how we can find our students. 3 00:00:11,240 --> 00:00:16,329 So let's go to the Mongoose website and let's search for find method. 4 00:00:16,340 --> 00:00:25,090 So again, under API and queries, click on that and we're going to see all the queries or the API. 5 00:00:25,100 --> 00:00:28,340 If you scroll down, I'm going to see what is called find. 6 00:00:28,340 --> 00:00:34,970 It's my round, I'm able to see it and we have a query, dot prototype, dot find. 7 00:00:34,970 --> 00:00:37,910 So the query is going to be the model. 8 00:00:37,910 --> 00:00:45,080 And then on that we have what is called prototype because with this one we can have access of all the 9 00:00:45,080 --> 00:00:47,900 methods on the instances of the objects. 10 00:00:47,930 --> 00:00:49,040 That is our model. 11 00:00:49,130 --> 00:00:58,460 So if I click on that, let's read more about the Find API and we have what is called the format here 12 00:00:58,580 --> 00:01:05,420 and the first parameter we take is called filter, meaning we can pass in optional argument and what 13 00:01:05,420 --> 00:01:06,230 is filter? 14 00:01:06,230 --> 00:01:09,410 And then I'm going to be an object with key value per. 15 00:01:09,560 --> 00:01:16,580 And next is we pass in callback function, but we are using promise and after that it retains what is 16 00:01:16,580 --> 00:01:18,590 called query, which is this. 17 00:01:18,590 --> 00:01:23,270 This represents the instance of the document that we are trying to find. 18 00:01:23,390 --> 00:01:30,950 And down here it has a couple of example using the async await and using the callback method. 19 00:01:30,950 --> 00:01:33,080 So let's see how I'm going to use it. 20 00:01:33,080 --> 00:01:35,720 So back to our code here. 21 00:01:36,020 --> 00:01:37,790 Let me comment this one. 22 00:01:38,000 --> 00:01:40,820 Otherwise it's going to create duplicate students. 23 00:01:40,820 --> 00:01:45,770 So here are going to be find or student. 24 00:01:45,770 --> 00:01:53,510 So here you go on this student model, we have a method called find and that is it. 25 00:01:53,510 --> 00:02:00,470 And remember because it's returns a promise, I need to handle it using promise. 26 00:02:00,710 --> 00:02:05,180 And here I have access to the individual student as students. 27 00:02:05,180 --> 00:02:10,850 When I use error function and console.log, they are going to be students, many students. 28 00:02:10,850 --> 00:02:19,280 So let me add here as student, okay, so here, if something goes wrong, let's catch it here and I 29 00:02:19,280 --> 00:02:25,460 have access to the error here and then cancel the error as that. 30 00:02:25,460 --> 00:02:29,030 So moment of truth, let's save it. 31 00:02:29,030 --> 00:02:31,250 And back to the terminal. 32 00:02:33,050 --> 00:02:36,800 Let's run the file again and let's see. 33 00:02:36,830 --> 00:02:39,410 I'm going to see all the students. 34 00:02:39,620 --> 00:02:45,590 And you see that we have an array, which means that it retains all the record. 35 00:02:45,590 --> 00:02:47,180 What is this? 36 00:02:47,180 --> 00:02:49,880 We have John and Emmanuel. 37 00:02:50,060 --> 00:02:56,660 So again, with a find we can pass in additional arguments as has been stated. 38 00:02:56,870 --> 00:03:04,490 So let's say that we want to find all student whose age is equal to 20 years and we can do that. 39 00:03:04,490 --> 00:03:08,510 So let's go ahead and create one student with different age. 40 00:03:08,510 --> 00:03:13,040 Now we going to see our query that we are going to run. 41 00:03:13,040 --> 00:03:18,050 So let me bring back the create and comment the find method here. 42 00:03:18,230 --> 00:03:23,540 So let me change the age, say 30 here and the name of the student. 43 00:03:23,570 --> 00:03:33,020 Let me call this one as age one and the person is from USA and with different courses, let's say three 44 00:03:33,410 --> 00:03:39,290 as that and let's see only one, only one cause here and I think it's cool. 45 00:03:39,290 --> 00:03:40,810 So back to the terminal. 46 00:03:41,210 --> 00:03:47,240 Let me clear it here and let me run it and let's see what we are going to get. 47 00:03:47,930 --> 00:03:48,530 All right. 48 00:03:48,530 --> 00:03:53,210 Now, this student has been created, so let me go ahead and fetch all the students. 49 00:03:53,210 --> 00:03:57,020 Now, you have three students with different ages. 50 00:03:57,020 --> 00:03:58,940 So now here we go. 51 00:03:59,390 --> 00:04:04,460 How can you find our student whose age is equal to 20 years? 52 00:04:04,460 --> 00:04:09,560 So find a student who's. 53 00:04:10,830 --> 00:04:13,590 Age is equal to 20 years. 54 00:04:13,590 --> 00:04:14,670 So here we go. 55 00:04:14,760 --> 00:04:20,250 You bring in the student and then find an inside aide. 56 00:04:20,279 --> 00:04:23,790 We pass in additional parameters called queries. 57 00:04:24,060 --> 00:04:27,660 So here you're going to say that if the age. 58 00:04:28,780 --> 00:04:31,270 Is equal to 20 years. 59 00:04:31,810 --> 00:04:32,770 That is it may. 60 00:04:33,100 --> 00:04:36,520 Then we need to handle the promise using this. 61 00:04:36,520 --> 00:04:43,330 So I have access to the actual student and then I can go ahead and console.log. 62 00:04:43,330 --> 00:04:44,560 The student here. 63 00:04:46,480 --> 00:04:49,300 And if something goes wrong, why not? 64 00:04:49,330 --> 00:04:51,670 We will catch it here as error. 65 00:04:54,250 --> 00:04:56,020 I start as the. 66 00:04:58,260 --> 00:04:58,890 Error. 67 00:05:00,510 --> 00:05:01,950 All right, so let's save it. 68 00:05:01,980 --> 00:05:03,030 Thing is. 69 00:05:03,100 --> 00:05:04,830 STUDENT Yeah. 70 00:05:05,850 --> 00:05:06,390 Yeah. 71 00:05:07,140 --> 00:05:09,210 You're going to be error. 72 00:05:09,260 --> 00:05:16,140 Okay, so now let's comment this one and let's see if you're going to get the actual student. 73 00:05:17,760 --> 00:05:18,510 Let's see. 74 00:05:18,510 --> 00:05:19,320 Run it. 75 00:05:19,320 --> 00:05:21,990 And now let's see what we have. 76 00:05:22,110 --> 00:05:29,940 And you can see that we have two student whose age are 20 and 20 years, and we can write this same 77 00:05:29,940 --> 00:05:31,710 logic with different syntax. 78 00:05:31,710 --> 00:05:36,480 So let me show you how we did when I was in Normal or MongoDB. 79 00:05:36,780 --> 00:05:44,850 We see that for MongoDB we also use the fine method, but instead we need to convert the cursor to array. 80 00:05:44,910 --> 00:05:47,310 But with Mongoose we don't do that. 81 00:05:47,310 --> 00:05:51,270 By default it convert the data into documents. 82 00:05:51,510 --> 00:05:55,710 That's why Mongoose makes our life easier when working with MongoDB. 83 00:05:55,830 --> 00:05:58,740 So that is how we can make use of the find. 84 00:05:58,740 --> 00:06:01,680 We can find a user with different properties. 85 00:06:01,770 --> 00:06:02,760 Then this video. 86 00:06:02,760 --> 00:06:05,970 Let's see how we can find a single user.