NOTE This file was generated by Descript 1 00:00:00,000 --> 00:00:01,410 Hi guys and welcome back. 2 00:00:01,590 --> 00:00:04,880 In this video, let me show you how to use Flask's app factory to 3 00:00:04,880 --> 00:00:10,280 create apps instead of just hard coding them over in the app file. 4 00:00:10,670 --> 00:00:14,570 The reason to use an app factory is because I mentioned earlier on, that you 5 00:00:14,570 --> 00:00:20,270 shouldn't create the database and store it in there directly in the main file. 6 00:00:20,480 --> 00:00:23,210 And by using an app factory, we're going to prevent a lot of 7 00:00:23,210 --> 00:00:25,070 problems that can happen later on. 8 00:00:25,190 --> 00:00:26,570 So let me show you how to do that. 9 00:00:26,570 --> 00:00:27,320 It's real simple. 10 00:00:28,165 --> 00:00:32,392 We've got app.py and in app.py, we're creating our app. 11 00:00:32,722 --> 00:00:34,822 We've got this app line there. 12 00:00:34,822 --> 00:00:38,362 We're then connecting to our database and we are storing 13 00:00:38,362 --> 00:00:39,562 the database over in the app. 14 00:00:39,952 --> 00:00:43,312 We're then also defining the end points of our app. 15 00:00:43,432 --> 00:00:46,732 So by all intents and purposes, we can say that this creates our app. 16 00:00:47,250 --> 00:00:53,240 However, there is one situation where this file might run multiple times. 17 00:00:53,690 --> 00:00:56,660 And that is when we deploy our applications. 18 00:00:57,080 --> 00:01:01,400 Sometimes the deployment mechanism can run this files multiple times. 19 00:01:01,480 --> 00:01:04,910 What will happen is we'll end up creating multiple different MongoClients. 20 00:01:04,930 --> 00:01:07,510 One for each time that the file runs. 21 00:01:07,540 --> 00:01:08,740 Even though we don't want to do that. 22 00:01:09,130 --> 00:01:12,190 So by using an app factory, we're going to solve that problem because 23 00:01:12,220 --> 00:01:16,930 even if the file runs multiple times, the deployment mechanism will be smart 24 00:01:16,930 --> 00:01:19,270 enough to not create multiple apps. 25 00:01:19,750 --> 00:01:23,780 All we have to do is create a function that must be called create_app. 26 00:01:23,800 --> 00:01:25,030 This must be the name. 27 00:01:25,470 --> 00:01:27,265 And put everything inside it. 28 00:01:27,262 --> 00:01:28,042 That's really it. 29 00:01:28,432 --> 00:01:31,252 The only thing we have to remember to do is at the end of the 30 00:01:31,252 --> 00:01:34,942 create_app function, return app. 31 00:01:35,272 --> 00:01:40,342 Because the Flask command line interface, the Flask run is going 32 00:01:40,342 --> 00:01:44,638 to automatically see that there is a create_app function, and it's 33 00:01:44,638 --> 00:01:46,718 going to run it to create your app. 34 00:01:47,193 --> 00:01:51,213 Note that you do have to put all your endpoint registrations 35 00:01:51,243 --> 00:01:52,293 inside the function. 36 00:01:52,473 --> 00:01:55,713 And if you have a lot of them, that's going to get quite long. 37 00:01:55,983 --> 00:01:59,253 But later on, we're going to learn about Flask blueprints which will 38 00:01:59,253 --> 00:02:03,573 allow us to extract these end points over to different files and just 39 00:02:03,573 --> 00:02:05,373 register them here with a single line. 40 00:02:05,373 --> 00:02:06,873 So it's going to be much simpler. 41 00:02:07,375 --> 00:02:09,865 If you have that, save the file and Flask run. 42 00:02:09,865 --> 00:02:11,035 It should just run your app. 43 00:02:11,035 --> 00:02:12,595 And it'll work in exactly the same way. 44 00:02:12,745 --> 00:02:15,415 This is just future proofing for later on. 45 00:02:15,928 --> 00:02:19,528 Also, if you're interested in testing your Flask apps, it's not something that 46 00:02:19,528 --> 00:02:22,408 we're going to cover in this course, but it's something that is very popular to do. 47 00:02:22,828 --> 00:02:26,368 Using the app factory allows you to run this function from your 48 00:02:26,368 --> 00:02:30,778 tests and create your app with different configuration parameters. 49 00:02:30,868 --> 00:02:31,798 If you want to do that. 50 00:02:32,178 --> 00:02:32,418 All right. 51 00:02:32,448 --> 00:02:34,008 Thank you guys for joining me in this video. 52 00:02:34,008 --> 00:02:36,318 Just a quick future-proofing like I said. 53 00:02:36,498 --> 00:02:40,198 But it's a very important and I recommend that you do this for all your Flask apps. 54 00:02:40,218 --> 00:02:42,918 Just make sure to name your function correctly and return app at the 55 00:02:42,918 --> 00:02:45,078 bottom, and you won't have any issues. 56 00:02:45,498 --> 00:02:48,018 Thanks guys for joining me, I'll see you in the next video.