1 00:00:02,029 --> 00:00:03,210 Now, in the last lecture, 2 00:00:03,210 --> 00:00:06,370 I mentioned that all these database operations 3 00:00:06,370 --> 00:00:09,340 in these route files are another aspect 4 00:00:09,340 --> 00:00:14,340 that could probably be refactored or outsourced 5 00:00:14,550 --> 00:00:18,400 to reduce the amount of code in those route files 6 00:00:18,400 --> 00:00:21,280 and put that code somewhere else. 7 00:00:21,280 --> 00:00:23,830 And for that, we got a specific pattern, 8 00:00:23,830 --> 00:00:24,960 which is very common. 9 00:00:24,960 --> 00:00:27,350 And which we can use here as well. 10 00:00:27,350 --> 00:00:29,920 As everything, it's not a must use pattern, 11 00:00:29,920 --> 00:00:32,500 but it is, as I just said, a very common pattern. 12 00:00:32,500 --> 00:00:36,190 And you will see it in a lot of web projects, though, 13 00:00:36,190 --> 00:00:37,690 not just there. 14 00:00:37,690 --> 00:00:40,370 Instead, it's a general programming pattern, 15 00:00:40,370 --> 00:00:44,080 which you will often see if you're building applications 16 00:00:44,080 --> 00:00:47,650 or websites that have user-facing parts. 17 00:00:47,650 --> 00:00:50,320 So things that can be seen by the user. 18 00:00:50,320 --> 00:00:54,300 And then a lot of backend logic parts you could say. 19 00:00:54,300 --> 00:00:56,380 And that's the MVC pattern, 20 00:00:56,380 --> 00:00:59,683 which stands for model view controller. 21 00:01:00,660 --> 00:01:02,270 Now, what are these things 22 00:01:02,270 --> 00:01:05,743 and how do we apply this pattern to our code base? 23 00:01:06,680 --> 00:01:10,120 The idea is that you split your main code 24 00:01:10,120 --> 00:01:13,650 that is involved in handling incoming requests 25 00:01:13,650 --> 00:01:18,373 and sending back responses into these three main areas. 26 00:01:19,350 --> 00:01:22,210 The model area is about all the logic 27 00:01:22,210 --> 00:01:25,500 that's related to working with your data source, 28 00:01:25,500 --> 00:01:28,220 your database, for example. 29 00:01:28,220 --> 00:01:30,700 So all the logic that is involved there. 30 00:01:30,700 --> 00:01:33,350 So for example, storing blog posts, 31 00:01:33,350 --> 00:01:35,990 fetching blog posts, and so on. 32 00:01:35,990 --> 00:01:39,960 That all should typically go into your model files. 33 00:01:39,960 --> 00:01:41,990 And of course, you will see how we can create 34 00:01:41,990 --> 00:01:44,923 such model files throughout this section. 35 00:01:46,020 --> 00:01:49,180 Now, here, you would therefore defined functions 36 00:01:49,180 --> 00:01:53,030 or methods for storing data in databases 37 00:01:53,030 --> 00:01:55,490 or fetching data from a database. 38 00:01:55,490 --> 00:01:59,080 Though, the model concept really applies 39 00:01:59,080 --> 00:02:01,900 no matter which data source you might be using. 40 00:02:01,900 --> 00:02:04,110 If you are working with file storage, 41 00:02:04,110 --> 00:02:07,403 you could also implement that with that MVC pattern. 42 00:02:08,810 --> 00:02:13,010 Now, the view part is the part we already are using. 43 00:02:13,010 --> 00:02:14,620 We have our templates. 44 00:02:14,620 --> 00:02:16,980 And the templates are the building blocks 45 00:02:16,980 --> 00:02:19,050 that contain the logic for presenting 46 00:02:19,050 --> 00:02:21,743 the data or the content to the user. 47 00:02:22,700 --> 00:02:24,460 So we're already doing that. 48 00:02:24,460 --> 00:02:26,970 And in those templates, we are of course, 49 00:02:26,970 --> 00:02:30,940 using the EJS templating language with all its tags 50 00:02:30,940 --> 00:02:35,050 that it's offering to us to output repeated content 51 00:02:35,050 --> 00:02:36,810 or conditional content. 52 00:02:36,810 --> 00:02:40,473 And therefore, that logic already is in the right place. 53 00:02:41,940 --> 00:02:45,310 In case you're wondering where else it should be stored. 54 00:02:45,310 --> 00:02:47,790 Keep in mind that when we got started 55 00:02:47,790 --> 00:02:50,660 with diving into backend development, 56 00:02:50,660 --> 00:02:55,660 we started by defining the HTML code that should be returned 57 00:02:56,180 --> 00:03:00,440 directly in our request handler functions. 58 00:03:00,440 --> 00:03:03,720 We didn't use templates right from the start. 59 00:03:03,720 --> 00:03:05,100 And there for example, 60 00:03:05,100 --> 00:03:09,100 we therefore didn't have that separate view logic 61 00:03:09,100 --> 00:03:11,210 or that separate view part. 62 00:03:11,210 --> 00:03:14,030 Instead, we had everything in our JavaScript code 63 00:03:14,030 --> 00:03:16,720 and everything in the same file. 64 00:03:16,720 --> 00:03:19,990 So we're using this view logic already, 65 00:03:19,990 --> 00:03:22,560 but we didn't use it right from the start. 66 00:03:22,560 --> 00:03:26,020 And using it as we're currently doing it is recommended, 67 00:03:26,020 --> 00:03:29,960 especially when using the MVC pattern, but not only then. 68 00:03:29,960 --> 00:03:33,763 Instead, views should always have separate template files. 69 00:03:35,490 --> 00:03:37,500 Now, the last part is the controller. 70 00:03:37,500 --> 00:03:40,710 And that's in the end a code that contains 71 00:03:40,710 --> 00:03:44,810 the logic for connecting your models to your views. 72 00:03:44,810 --> 00:03:48,320 So that is the part where you work with your models 73 00:03:48,320 --> 00:03:51,800 to tell them to fetch data, for example. 74 00:03:51,800 --> 00:03:56,410 And where you then pass that fetched data into your views. 75 00:03:56,410 --> 00:04:00,230 And therefore, controllers are typically the functions 76 00:04:00,230 --> 00:04:04,340 that are executed when your routes trigger. 77 00:04:04,340 --> 00:04:06,260 So you could say that the code 78 00:04:06,260 --> 00:04:09,930 in your route files is your controller code. 79 00:04:09,930 --> 00:04:13,410 Though, at the moment, since we're not using models at all, 80 00:04:13,410 --> 00:04:17,200 we don't have correct controllers in our website 81 00:04:17,200 --> 00:04:19,470 because we're doing way too much work 82 00:04:19,470 --> 00:04:22,350 in those controllers at the moment. 83 00:04:22,350 --> 00:04:24,360 And therefore, that's the MVC pattern. 84 00:04:24,360 --> 00:04:26,260 And we're not using it yet. 85 00:04:26,260 --> 00:04:28,840 We're only using the view part. 86 00:04:28,840 --> 00:04:31,940 Therefore, in the next lectures, we're going to apply 87 00:04:31,940 --> 00:04:35,810 the MVC pattern on the website code we have here. 88 00:04:35,810 --> 00:04:37,470 And you will learn step by step 89 00:04:37,470 --> 00:04:40,670 how you implement it so that you can implement 90 00:04:40,670 --> 00:04:43,813 it in any website project you might be working on.