1 1 00:00:00,390 --> 00:00:01,590 In this video we're going to 2 2 00:00:01,590 --> 00:00:03,510 look at the app structure. 3 3 00:00:03,510 --> 00:00:06,460 What the app is going to do in this section 4 4 00:00:06,460 --> 00:00:09,780 is it's going to tell our users when an item 5 5 00:00:09,780 --> 00:00:14,740 that they want to buy online goes under their desired price. 6 6 00:00:14,740 --> 00:00:18,460 For example, if they have their favourite department store, 7 7 00:00:18,460 --> 00:00:21,700 they can go into the website, find the web address 8 8 00:00:21,700 --> 00:00:24,960 of the item they're interested in, give it to us, 9 9 00:00:24,960 --> 00:00:26,930 and tell us how to find the price 10 10 00:00:26,930 --> 00:00:31,100 of the item on the website, and then we will message them 11 11 00:00:31,100 --> 00:00:33,540 later on when there's a sale or something like that. 12 12 00:00:33,540 --> 00:00:35,340 So that's the purpose of the app, 13 13 00:00:35,340 --> 00:00:38,060 and how we're gonna do this is by 14 14 00:00:38,980 --> 00:00:42,010 allowing the user to give us all the information we need, 15 15 00:00:42,010 --> 00:00:44,750 storing it, and the every now and then, 16 16 00:00:44,750 --> 00:00:46,910 maybe every day, maybe every hour, 17 17 00:00:46,910 --> 00:00:50,650 run a programme that will check the pricing 18 18 00:00:50,650 --> 00:00:52,233 and send the users an email. 19 19 00:00:53,320 --> 00:00:58,320 In order to create the app, we're going to use the MVC 20 20 00:00:58,430 --> 00:01:01,410 model for structuring a web application like this one. 21 21 00:01:01,410 --> 00:01:04,820 MVC stands for model view controller. 22 22 00:01:04,820 --> 00:01:07,370 Those three things are important things 23 23 00:01:07,370 --> 00:01:09,320 in a web application like this one. 24 24 00:01:09,320 --> 00:01:12,000 It's a very popular way of structuring an app. 25 25 00:01:12,000 --> 00:01:16,680 So the models define what the application 26 26 00:01:16,680 --> 00:01:20,220 understands about the things that it deals with. 27 27 00:01:20,220 --> 00:01:22,900 For example, in this application, we can have models 28 28 00:01:22,900 --> 00:01:26,090 such as the item the user's interested in, 29 29 00:01:26,090 --> 00:01:29,840 the store that an item is a part of, 30 30 00:01:29,840 --> 00:01:31,680 an alert, 31 31 00:01:31,680 --> 00:01:35,660 what price a user's interested in for a certain item. 32 32 00:01:35,660 --> 00:01:38,090 Those things could be models, 33 33 00:01:38,090 --> 00:01:39,170 because those are things 34 34 00:01:39,170 --> 00:01:42,700 that our application deals with internally. 35 35 00:01:42,700 --> 00:01:44,807 Then we've got the views, 36 36 00:01:44,807 --> 00:01:47,280 and a view in one of these apps 37 37 00:01:47,280 --> 00:01:50,190 is what the user sees and interacts with. 38 38 00:01:50,190 --> 00:01:53,360 So in this case, we're gonna be creating a web app, 39 39 00:01:53,360 --> 00:01:57,120 so the user is going to be looking at a web view. 40 40 00:01:57,120 --> 00:01:59,630 Something that they can look at on their browser. 41 41 00:01:59,630 --> 00:02:02,060 It's gonna be using HTML and CSS 42 42 00:02:02,060 --> 00:02:04,030 and so on in order to display. 43 43 00:02:04,030 --> 00:02:06,520 And our Flask application is going to be responsible 44 44 00:02:06,520 --> 00:02:09,010 for serving those views to our user 45 45 00:02:09,010 --> 00:02:10,260 so they can look at them. 46 46 00:02:11,120 --> 00:02:12,500 So that's the M and the V, 47 47 00:02:12,500 --> 00:02:15,070 and finally we've got the C, which is controller. 48 48 00:02:15,070 --> 00:02:18,110 A controller is essentially everything else 49 49 00:02:18,110 --> 00:02:19,680 in an application like this one. 50 50 00:02:19,680 --> 00:02:22,400 So once we have the view that the user interacts with 51 51 00:02:22,400 --> 00:02:25,420 and the models that our programme understands 52 52 00:02:25,420 --> 00:02:28,260 about the context it's in for this application, 53 53 00:02:28,260 --> 00:02:29,500 the controller is responsible 54 54 00:02:29,500 --> 00:02:34,270 for handling user inputs, for dispatching user outputs, 55 55 00:02:34,270 --> 00:02:36,650 it's responsible for creating models 56 56 00:02:36,650 --> 00:02:39,410 and storing them in data bases, and making sure 57 57 00:02:39,410 --> 00:02:43,760 that the models are valid and for retrieving prices 58 58 00:02:43,760 --> 00:02:46,250 from the websites that our users are interested in, 59 59 00:02:46,250 --> 00:02:47,083 that sort of stuff. 60 60 00:02:47,083 --> 00:02:49,810 So the controller is sort of the engine 61 61 00:02:49,810 --> 00:02:51,560 that runs the whole app. 62 62 00:02:51,560 --> 00:02:54,210 Okay, enough about what these things are. 63 63 00:02:54,210 --> 00:02:57,630 We are gonna start by creating the different folders, 64 64 00:02:57,630 --> 00:02:59,660 and we're gonna go for Python Packages 65 65 00:02:59,660 --> 00:03:02,420 and I'm gonna have a common Python Package. 66 66 00:03:02,420 --> 00:03:04,270 If you go to Python Package using PyCharm, 67 67 00:03:04,270 --> 00:03:07,440 what you end up is a dunder init file, 68 68 00:03:07,440 --> 00:03:09,950 so that's underscore underscore init, underscore underscore. 69 69 00:03:09,950 --> 00:03:11,430 Two underscores on each side, 70 70 00:03:11,430 --> 00:03:13,960 and that tells Python that this is a package 71 71 00:03:13,960 --> 00:03:15,910 that you can import things from. 72 72 00:03:15,910 --> 00:03:17,670 If you don't put the dunder init file, 73 73 00:03:17,670 --> 00:03:20,270 then you cannot import things from it. 74 74 00:03:20,270 --> 00:03:22,850 So that's important, so that's our common package, 75 75 00:03:22,850 --> 00:03:24,500 where you're gonna put things like 76 76 00:03:24,500 --> 00:03:26,050 a date of interaction files, 77 77 00:03:26,050 --> 00:03:28,860 or any utils like to 78 78 00:03:28,860 --> 00:03:32,800 hash passwords or check validity of emails 79 79 00:03:32,800 --> 00:03:34,100 and things like that. 80 80 00:03:34,100 --> 00:03:36,040 Things that you can use throughout your application 81 81 00:03:36,040 --> 00:03:39,430 and aren't really a model view or a controller. 82 82 00:03:39,430 --> 00:03:41,220 Then we're gonna have our models. 83 83 00:03:41,220 --> 00:03:44,870 Then we are going to have our templates 84 84 00:03:44,870 --> 00:03:48,150 which are essentially, I'm gonna say the view, 85 85 00:03:48,150 --> 00:03:50,540 but this is what the user's going to look at. 86 86 00:03:50,540 --> 00:03:52,150 This is the HTML files 87 87 00:03:52,150 --> 00:03:54,350 that our users are going to be served. 88 88 00:03:54,350 --> 00:03:57,820 And finally I'm going to create a package called the views. 89 89 00:03:57,820 --> 00:04:00,640 And I'm calling it views instead of controllers, 90 90 00:04:00,640 --> 00:04:03,390 and there's a specific reason for that. 91 91 00:04:03,390 --> 00:04:07,610 In this application, the controllers 92 92 00:04:07,610 --> 00:04:11,260 are really just going to be serving the user 93 93 00:04:11,260 --> 00:04:12,983 with the templates. 94 94 00:04:13,906 --> 00:04:17,380 And to some extent they're also going to be receiving 95 95 00:04:17,380 --> 00:04:20,160 in some cases some data from a template, 96 96 00:04:20,160 --> 00:04:23,700 like a form, like HTML form that the user can submit. 97 97 00:04:23,700 --> 00:04:27,750 But we don't have any separate controllers 98 98 00:04:27,750 --> 00:04:31,030 outside of sending the user our templates 99 99 00:04:31,030 --> 00:04:33,490 and receiving data from those templates. 100 100 00:04:33,490 --> 00:04:37,270 So in this application, the views on the templates 101 101 00:04:37,270 --> 00:04:39,180 work very closely together 102 102 00:04:39,180 --> 00:04:42,270 such that I'm calling my controllers views 103 103 00:04:42,270 --> 00:04:46,150 because they're only responsible for serving the views. 104 104 00:04:46,150 --> 00:04:48,180 You can choose to call this controllers, 105 105 00:04:48,180 --> 00:04:49,340 and these views. 106 106 00:04:49,340 --> 00:04:52,800 If you want, I know that this is a little bit confusing, 107 107 00:04:52,800 --> 00:04:55,000 but I'm sure it'll be clearer as we develop 108 108 00:04:55,000 --> 00:04:57,110 exactly what these are doing. 109 109 00:04:57,110 --> 00:05:00,510 Alright, so this is the structure of our application. 110 110 00:05:00,510 --> 00:05:02,560 We are going to have our app.py, 111 111 00:05:02,560 --> 00:05:04,510 and then our views and templates, 112 112 00:05:04,510 --> 00:05:06,150 which our responsible for handling 113 113 00:05:06,150 --> 00:05:08,400 what the user sees and what the user sends us. 114 114 00:05:08,400 --> 00:05:10,920 Then we've got the models, which are going to contain 115 115 00:05:10,920 --> 00:05:14,000 what our application understands about the context it's in, 116 116 00:05:14,000 --> 00:05:17,440 such as the items, stores, alerts, et cetera. 117 117 00:05:17,440 --> 00:05:19,240 And then we've got some common files 118 118 00:05:19,240 --> 00:05:21,980 which are going to deal with common things 119 119 00:05:21,980 --> 00:05:24,277 like data interactions and so on. 120 120 00:05:24,277 --> 00:05:25,730 That's it for this video. 121 121 00:05:25,730 --> 00:05:26,890 Thank you for joining me. 122 122 00:05:26,890 --> 00:05:28,280 Let's continue in the next one. 123 123 00:05:28,280 --> 00:05:29,230 I'll see you there.