1 00:00:00,325 --> 00:00:01,541 - [Instructor] Hi and welcome back. 2 00:00:01,541 --> 00:00:03,292 In this video, we're going to simplify 3 00:00:03,292 --> 00:00:07,459 our entire code base slightly more by using SQLAlchemy. 4 00:00:08,624 --> 00:00:09,941 Did you know that SQLAlchemy 5 00:00:09,941 --> 00:00:12,858 can create our data.db file for us? 6 00:00:14,207 --> 00:00:16,550 Well, if you didn't, now you do. 7 00:00:16,550 --> 00:00:19,075 We no longer need the create table script, 8 00:00:19,075 --> 00:00:21,874 so I'm just gonna delete that 9 00:00:21,874 --> 00:00:23,359 and I'm also going to delete data.db 10 00:00:23,359 --> 00:00:25,041 just so you'll believe me 11 00:00:25,041 --> 00:00:29,267 when I say that SQLAlchemy will create it for us. 12 00:00:29,267 --> 00:00:31,032 In our app.py however, 13 00:00:31,032 --> 00:00:32,849 we of course have to tell SQLAlchemy 14 00:00:32,849 --> 00:00:34,491 to create the database for us. 15 00:00:34,491 --> 00:00:36,991 It won't just magically do it. 16 00:00:38,358 --> 00:00:39,950 Although actually that's a bit of a lie. 17 00:00:39,950 --> 00:00:42,657 It does create it but it doesn't create any tables in it, 18 00:00:42,657 --> 00:00:44,475 so then that's not very useful. 19 00:00:44,475 --> 00:00:46,357 It creates the data.db file 20 00:00:46,357 --> 00:00:49,140 but it doesn't put anything inside it, 21 00:00:49,140 --> 00:00:50,650 so then you'll get the errors 22 00:00:50,650 --> 00:00:53,499 where the database doesn't exist. 23 00:00:53,499 --> 00:00:54,450 So what we're gonna do here 24 00:00:54,450 --> 00:00:57,692 is we're going to use a Flask decorator. 25 00:00:57,692 --> 00:00:59,966 We're moving backwards to some extent. 26 00:00:59,966 --> 00:01:01,042 We're not really moving backwards 27 00:01:01,042 --> 00:01:03,812 but we're going a bit backwards in our knowledge 28 00:01:03,812 --> 00:01:07,382 and using something that comes directly from Flask 29 00:01:07,382 --> 00:01:10,057 as opposed to any of the extensions. 30 00:01:10,057 --> 00:01:14,224 So what we're gonna do is @app.before_first_request 31 00:01:15,625 --> 00:01:16,475 and this is a decorator 32 00:01:16,475 --> 00:01:19,583 that is going to affect the method below it 33 00:01:19,583 --> 00:01:21,466 and it's going to run that method 34 00:01:21,466 --> 00:01:24,716 before the first request into this app. 35 00:01:27,231 --> 00:01:30,741 And this method is going to be called create_tables 36 00:01:30,741 --> 00:01:34,908 and all it's going to do is it's going to say db.create_all. 37 00:01:37,116 --> 00:01:41,042 Now what is gonna happen is that before the first request, 38 00:01:41,042 --> 00:01:42,700 no matter what request that is, 39 00:01:42,700 --> 00:01:45,100 but before the first request runs, 40 00:01:45,100 --> 00:01:46,974 it's gonna run this 41 00:01:46,974 --> 00:01:51,217 and that is going to create this file there, data.db, 42 00:01:51,217 --> 00:01:53,667 and it's gonna create all of the tables in the file 43 00:01:53,667 --> 00:01:55,834 unless they exist already. 44 00:01:56,750 --> 00:01:59,283 Naturally, if we were using PostgreSQL, 45 00:01:59,283 --> 00:02:01,116 it would also create all the tables there 46 00:02:01,116 --> 00:02:04,907 unless they exist already, and so on. 47 00:02:04,907 --> 00:02:07,858 So now what we can do is go to Postman. 48 00:02:07,858 --> 00:02:09,967 In fact, to make sure that your code is running, 49 00:02:09,967 --> 00:02:11,632 which it is in my case, 50 00:02:11,632 --> 00:02:14,450 go to Postman and you can, for example, register, 51 00:02:14,450 --> 00:02:18,107 and notice how that took slightly longer to run 52 00:02:18,107 --> 00:02:21,500 and indeed you can see that data.db is now here 53 00:02:21,500 --> 00:02:24,000 and SQLAlchemy has created it. 54 00:02:24,925 --> 00:02:26,407 So that's it. 55 00:02:26,407 --> 00:02:28,349 That's how you can create the tables there 56 00:02:28,349 --> 00:02:29,432 and you no longer need to worry 57 00:02:29,432 --> 00:02:32,217 about running the create table script. 58 00:02:32,217 --> 00:02:35,928 Just include that and the tables will be created for you. 59 00:02:35,928 --> 00:02:37,391 That's everything for this video 60 00:02:37,391 --> 00:02:39,377 and I'll see you on the next one.