WEBVTT 00:00.320 --> 00:03.170 Okay, so now we've got our DB initializer class. 00:03.170 --> 00:06.380 Let's just review this, make sure everything looks okay. 00:06.380 --> 00:08.300 And we've got our init db. 00:09.080 --> 00:13.160 And we create a scope using the using keyword. 00:13.250 --> 00:16.070 And we use the app services Create scope. 00:16.070 --> 00:22.820 Now when we using it this way and this services concept, it may become clearer once we start to look 00:22.850 --> 00:24.440 at dependency injection. 00:24.440 --> 00:29.660 Because what we're using here is a service that we've defined in our program class. 00:29.930 --> 00:34.490 And I mentioned earlier, albeit very briefly, about dependency injection. 00:34.490 --> 00:41.360 We haven't looked at that yet, and we cannot use it yet when we're doing something that involves the 00:41.360 --> 00:48.260 program class, because dependency injection isn't available until our application is actually running. 00:48.350 --> 00:54.170 Now, the point where we're going to use our DB initializer class is before our application has actually 00:54.170 --> 00:54.980 started. 00:54.980 --> 00:59.150 We're going to use this code just before we get to the run command. 00:59.750 --> 01:06.520 After we've run our application, then our services we can use for dependency injection Projection purposes, 01:06.520 --> 01:11.080 but we cannot do it where we're going to seed our data into the database. 01:11.650 --> 01:15.880 Now we've got another ellipses here to tell us that we can do something. 01:15.910 --> 01:21.730 And it tells us that member seed data does not access instance data and can be marked as static. 01:21.730 --> 01:22.840 So okay, fine. 01:22.840 --> 01:25.180 Let's do that and we'll use the ellipses. 01:25.690 --> 01:27.700 And can we use the ellipses. 01:27.730 --> 01:31.300 And well it's not letting us do anything automatically. 01:31.330 --> 01:34.840 So perhaps we just need to say private static void here. 01:34.840 --> 01:38.110 And then the warning or ellipses goes away. 01:38.110 --> 01:41.200 And the ellipses are not warnings or errors by Luella. 01:41.200 --> 01:45.730 Just advice to say, hey, you can do something slightly better here. 01:45.730 --> 01:50.920 And in this case, when it's saying it doesn't need access to instance data, it means we're not injecting 01:50.920 --> 01:52.660 anything into this class. 01:52.660 --> 01:59.170 Therefore, this can be marked as static because it doesn't depend on anything else. 01:59.170 --> 02:03.820 It's only depending or only using what's already inside this class. 02:03.820 --> 02:06.760 So this can be what's referred to as a static method. 02:06.760 --> 02:11.440 We'll get more into this syntax as we use it as we build our application. 02:11.530 --> 02:17.800 So after we've got access to the context, we then call the Setdata method, which will then migrate 02:17.800 --> 02:19.720 the database if necessary. 02:19.900 --> 02:21.880 It's going to check for any pending migrations. 02:21.880 --> 02:28.990 And then if it doesn't have a database then it will create the database and apply any pending migrations. 02:29.020 --> 02:30.730 And that's going to happen every time. 02:30.730 --> 02:34.690 So whenever we restart our app this method is always going to get called. 02:35.410 --> 02:37.150 Then we're going to check to see if we've got any products. 02:37.150 --> 02:40.000 And if we do have any products, we don't need to seed any more products in. 02:40.000 --> 02:42.400 So we're just returning out of this method. 02:42.400 --> 02:46.930 And then we create our new list of products and save them into our database. 02:47.350 --> 02:50.500 So we need to call this method inside our program class. 02:50.500 --> 02:54.700 And as mentioned we need to do this before our application is started. 02:54.700 --> 03:02.080 So in order to do that we can use DB initializer and get that into our program class. 03:02.080 --> 03:05.050 And we need to use the init db method. 03:05.080 --> 03:11.950 Now I don't have access to the init db method in here, because I also need to make this a static method. 03:12.430 --> 03:19.600 And a static method means effectively that I can use the method from this class without actually creating 03:19.600 --> 03:25.570 a new instance of this class, so I don't need to say new DB initializer. 03:25.570 --> 03:28.210 If I've got a static method in here that I'm calling. 03:28.210 --> 03:33.790 So if I go back to the program class now, I've got access to the init db method and I can just pass 03:33.790 --> 03:34.240 this. 03:34.240 --> 03:41.860 It's required parameter, which is the app that we're using inside the DB initializer, the web application 03:41.890 --> 03:42.310 app. 03:42.340 --> 03:45.820 Now we've got access to the init db. 03:45.940 --> 03:48.190 We can now go ahead and create our database. 03:48.190 --> 03:49.480 But we've already got a database. 03:49.480 --> 03:55.000 So let's remove that database so that we can see what happens when we restart our API. 03:55.030 --> 04:00.190 To make sure that the database gets created and we seed our data in there. 04:00.280 --> 04:02.140 So let's go back to the terminal. 04:02.140 --> 04:03.880 And I'm just going to clear the screen here. 04:03.880 --> 04:08.710 And please make sure your web application is stopped at this point. 04:08.710 --> 04:12.400 And we're going to use the Net AF database. 04:12.400 --> 04:16.570 And we can use the drop command which is going to remove our database. 04:16.570 --> 04:20.380 So I'll press return and we should get a confirmation saying are we sure. 04:20.410 --> 04:23.120 I'm going to say yes and press return. 04:23.120 --> 04:24.650 And this drops the database. 04:24.650 --> 04:32.690 And what that really means in the physical terms is our store DB is no longer part of our project files. 04:32.690 --> 04:40.010 And then in order to create that database and see the data because of this line of code, then we can 04:40.010 --> 04:41.030 just restart our app. 04:41.030 --> 04:46.430 So I'm just going to say well clear the window and say dotnet watch and we'll keep an eye on the terminal, 04:46.460 --> 04:49.250 the logs so that we can see what's happening. 04:49.250 --> 04:52.460 But what should happen and what we should see is something like this. 04:52.490 --> 04:59.780 We see a lot of inserts into products, which means our data is being seeded into the database. 04:59.780 --> 05:05.840 And we can further confirm that by taking a look at Solution Explorer, clicking on the store DB. 05:06.110 --> 05:10.550 And what we should see is that we've now got 18 products in our database. 05:10.550 --> 05:12.950 As easy as that. 05:12.950 --> 05:14.510 So great. 05:14.810 --> 05:21.830 And next let's see how we can use this data to return to query our database and return this data from 05:21.830 --> 05:26.930 the database in response to an HTTP request, which we'll take a look at next.