WEBVTT 00:00.020 --> 00:03.560 Okay, now it's time to take a look at using Entity Framework. 00:03.560 --> 00:08.240 Now that we have discussed it, and the first thing we're going to do is install the package that we 00:08.240 --> 00:10.430 need to make use of this. 00:10.430 --> 00:12.290 So we're going to go to our extensions. 00:12.290 --> 00:17.540 One of them that we installed earlier on that you should have is NuGet Gallery. 00:17.540 --> 00:21.980 So please do make sure you have this extension installed and available. 00:21.980 --> 00:23.900 And the way that we use NuGet Gallery. 00:23.900 --> 00:29.120 If you open up your terminal and let's just clear that window, then what you'll find is you've got 00:29.150 --> 00:30.890 a tab here for NuGet. 00:30.890 --> 00:37.040 And this is how we go ahead and install NuGet packages into our project. 00:37.040 --> 00:42.800 What we want to search for here is Microsoft Dot Entity Framework Core. 00:43.310 --> 00:48.650 And it should go ahead and search similarly named packages. 00:48.650 --> 00:52.940 And lest we've made a mistake and I've spelt Microsoft wrong. 00:52.940 --> 00:55.760 So that should be Microsoft Entity Framework Core. 00:55.760 --> 00:59.570 And this should bring up a list of packages related to that. 00:59.780 --> 01:06.470 Now we actually need two packages from this we we need Microsoft Entity Framework core dot SQLite. 01:06.500 --> 01:10.580 Please install the package with the same name. 01:10.580 --> 01:13.340 Don't install a similarly named one such as SQLite core. 01:13.370 --> 01:14.450 That's not going to work for you. 01:14.480 --> 01:18.140 You're going to get some strange errors when we start to use this. 01:18.140 --> 01:21.770 So please install Microsoft Entity Framework Core SQLite. 01:22.190 --> 01:26.390 Please pick the version that matches the major version of the runtime. 01:26.390 --> 01:29.360 In my case, it's going to be version nine of this package. 01:29.630 --> 01:34.760 If you're on dotnet nine, then just pick the the one that relates to what you're using. 01:34.790 --> 01:38.840 Of course, if you're on dotnet ten you would select version ten of this. 01:38.870 --> 01:41.900 It should be updated in line with dotnet as well. 01:41.900 --> 01:48.350 So let's go ahead and add this by using the plus button and sending it to or installing it into API 01:48.350 --> 01:49.550 Csproj. 01:49.910 --> 01:57.860 And what we also need is Microsoft Entity Framework Core Design, which we need to install so that we 01:57.860 --> 02:01.320 can create migrations with Entity Framework. 02:01.320 --> 02:04.650 So we're also going to install this one into API. 02:04.680 --> 02:06.900 Csproj as well. 02:07.500 --> 02:13.770 And once those have been installed, then what you should be able to do is go to Solution Explorer. 02:13.800 --> 02:21.060 Click on API and you should see the newly added packages Microsoft Entity Framework, Core Design and 02:21.060 --> 02:23.940 Microsoft Entity Framework Core SQL Lite. 02:23.940 --> 02:27.960 So please double check you have these installed. 02:28.200 --> 02:33.600 Now that we have this, we can make use of Entity Framework classes inside our project. 02:33.600 --> 02:37.890 And we're going to go to Solution Explorer inside the API. 02:37.920 --> 02:40.380 Let's just right click and say New Folder. 02:40.380 --> 02:45.180 And we're going to call this one data for all data related code. 02:45.180 --> 02:47.640 And we're going to create a new file inside here. 02:47.640 --> 02:51.600 And we're going to call it store context and not a new file. 02:51.600 --> 02:57.570 We need to create a new class called Store Context and press return. 02:57.600 --> 03:04.650 Now this class is going to derive from an entity framework class called Dbcontext. 03:04.650 --> 03:10.950 So the way that we derive from another class is we add a colon after the name of the class, and we're 03:10.950 --> 03:13.080 going to say dbcontext. 03:13.320 --> 03:17.430 And this should bring in the available options. 03:17.430 --> 03:21.180 And we want Dbcontext that's coming from Microsoft Entity Framework Core. 03:21.270 --> 03:27.750 So I'll press return to select that and we get the using statement added at the top so that this class, 03:27.750 --> 03:31.590 this Dbcontext class is coming from list namespace. 03:31.950 --> 03:32.610 That's fine. 03:32.610 --> 03:39.330 Now in order to use the Dbcontext and provide it with things like the connection string to our database 03:39.360 --> 03:43.890 or our database server, we need to provide this with a constructor. 03:44.160 --> 03:50.910 So a constructor in C-sharp world is when we create a new instance of the store context, then it runs 03:50.910 --> 03:52.890 the code inside the constructor. 03:52.890 --> 03:59.460 And the way that we create a constructor is we say Ctor to get the snippet for a constructor, and then 03:59.460 --> 04:04.070 we tell it what parameters, if any, that it needs, that we need to provide. 04:04.070 --> 04:08.960 When we create a new instance of this store context and the parameters that we do need to provide for 04:08.960 --> 04:09.140 this. 04:09.170 --> 04:14.450 We need to provide this with some DB context options and say options. 04:14.450 --> 04:16.970 But there's a better way of creating a constructor. 04:17.000 --> 04:19.310 Now in C-sharp eight and above. 04:19.310 --> 04:22.820 And we get these ellipses underneath the store context. 04:22.820 --> 04:27.650 And it tells us that we can use a primary constructor. 04:27.650 --> 04:33.620 So if we go ahead and use this, and what we have available to us is a quick fix, when we see this 04:33.620 --> 04:40.070 light bulb or we see ellipses or we see an underline in our code, we can hover over this and we can 04:40.250 --> 04:45.860 either select the quick fix here, we can use the light bulb here, or we can use the shortcut key combination, 04:45.860 --> 04:48.110 which in my case is command and period. 04:48.170 --> 04:50.030 And this will open up a menu. 04:50.030 --> 04:52.280 And it will give us an option of what to use. 04:52.280 --> 04:54.890 And we can use the primary constructor. 04:54.890 --> 04:58.190 And then we pass in the options. 04:58.190 --> 05:03.970 Now these options have to be passed to the class that we're deriving from. 05:03.970 --> 05:11.080 So as well as Dbcontext here, we need to add parentheses and specify options so that these options, 05:11.080 --> 05:17.500 which is going to contain our connection string, gets passed up to the Entity Framework Dbcontext. 05:17.530 --> 05:22.030 Now if we hover over the Dbcontext then this gives us documentation about the Dbcontext. 05:22.060 --> 05:25.330 Although because I've specified options, let's just remove that for the time being. 05:25.360 --> 05:30.250 Hover over the Dbcontext just to get a description about what this class actually does. 05:30.550 --> 05:38.170 Now this represents a session with the database and can be used to query and save instances of our entities. 05:38.170 --> 05:44.380 So when it comes to saving a product into the database or querying for a product in the database, then 05:44.380 --> 05:48.850 we use it via our store context which derives from the Dbcontext. 05:49.150 --> 05:54.010 Now, if you've done some coding before, you may well have heard of the unit of work and repository 05:54.010 --> 05:54.850 patterns. 05:54.880 --> 05:59.650 The Dbcontext is a combination of these patterns. 05:59.680 --> 06:05.950 Now we can also use them inside our project if we want to, or because this is a combination of those 06:05.950 --> 06:09.550 two patterns, we don't actually have to use them in our project. 06:09.580 --> 06:14.290 Now, I have covered those patterns on different courses, so I'm not going to cover that on this one. 06:14.320 --> 06:16.240 I'm going to keep things nice and simple. 06:16.240 --> 06:22.510 And because the Dbcontext is already a combination of these two patterns, we don't have to use it in 06:22.510 --> 06:23.860 our project. 06:23.890 --> 06:25.420 So that's the dbcontext. 06:25.420 --> 06:27.040 And we also need to specify. 06:27.070 --> 06:28.360 Well let's put the options back in. 06:28.390 --> 06:31.180 Now I've just got the description from that. 06:31.210 --> 06:35.020 We also need to specify inside here our different entities. 06:35.020 --> 06:37.330 And we do that we create a property. 06:37.330 --> 06:40.330 And this is going to be a type of dbset. 06:40.450 --> 06:49.750 And if we hover over the dbset then this is or can be used to query and save instances of our entity. 06:49.750 --> 06:56.770 And Linq queries against a DB set will be translated into queries against the database. 06:56.770 --> 07:03.050 So what this means is when we use Entity Framework is we write our code in C-sharp, which SQL doesn't 07:03.050 --> 07:12.320 understand, and then Entity Framework translates those C-sharp or that C-sharp code into SQL commands 07:12.320 --> 07:14.420 that our database does understand. 07:14.450 --> 07:16.070 So we only need to use one language. 07:16.070 --> 07:19.220 We don't need to know C-sharp and SQL syntax. 07:19.220 --> 07:24.080 We just need to know C-sharp to be able to query our database. 07:24.440 --> 07:26.540 Now our DB set takes a type. 07:26.540 --> 07:29.390 So we put the type of thing in angle brackets. 07:29.390 --> 07:31.490 And this is going to be a type of product. 07:31.520 --> 07:32.750 So I'll press return. 07:32.750 --> 07:35.330 And then we give our property a name. 07:35.450 --> 07:37.460 And I'm going to call it products. 07:37.460 --> 07:42.770 And because we're getting the warning here because of the type of property, this is being a DB set. 07:42.800 --> 07:47.510 It says must contain a non-null value or consider adding a required modifier. 07:47.540 --> 07:49.100 This actually caught me by surprise. 07:49.100 --> 07:54.380 This must have been recently added to Entity Framework version nine or dotnet nine, because we didn't 07:54.380 --> 07:57.230 used to have to add the required modifier here. 07:57.230 --> 07:59.210 So I'm going to see how this goes. 07:59.210 --> 08:00.560 It maybe it will cause us a problem. 08:00.560 --> 08:01.250 Maybe it will not. 08:01.280 --> 08:06.200 I was not expecting to need to use that inside this particular class anyway. 08:06.230 --> 08:10.040 Now that we have this available in here, we need to tell our startup code about this. 08:10.070 --> 08:18.710 Now our startup code is contained inside the Program.cs, and our Dbcontext class is something that 08:18.710 --> 08:23.840 we're going to want to use in other parts of our application so that we can query our database. 08:23.870 --> 08:29.660 So for that reason, we add this as a service inside our program class. 08:29.660 --> 08:32.660 And we're going to specify builder dot services. 08:32.660 --> 08:38.180 And there's a special method inside here to add our dbcontext. 08:38.300 --> 08:41.840 Inside the angle brackets we specify store context. 08:41.930 --> 08:44.600 And then we provide it with the options. 08:44.600 --> 08:47.300 And the options are what we specify here. 08:47.300 --> 08:50.900 So we need to pass this to our store context. 08:50.900 --> 08:56.480 Because when we add this as a service the framework will create a new instance of our store context. 08:56.510 --> 09:00.450 So it needs to know about the options we're going to provide to it. 09:00.450 --> 09:02.580 So back to our program class we're going to specify. 09:02.610 --> 09:03.360 Opt. 09:03.510 --> 09:06.420 And then we provide this as an expression. 09:06.420 --> 09:10.950 So we effectively add an arrow with the equals and angle brackets. 09:10.950 --> 09:15.450 And then before the closing parentheses we'll add curly brackets. 09:15.450 --> 09:18.510 And we close off the statement with a semicolon. 09:18.510 --> 09:24.210 And then for the options we can say options and use SQL Lite. 09:24.540 --> 09:28.380 And then we pass SQL light its connection string. 09:28.380 --> 09:30.540 Now we're going to get this from configuration. 09:30.750 --> 09:36.000 And how we access our configuration is we specify builder dot configuration. 09:36.000 --> 09:42.120 And there's a special configuration value inside here called get connection string. 09:42.390 --> 09:44.250 And inside get connection string. 09:44.250 --> 09:47.010 We're going to specify default connection. 09:47.430 --> 09:50.580 And that's what we're going to create soon. 09:50.760 --> 09:55.860 So our code knows where to find our database server. 09:56.130 --> 10:00.570 And we're going to configure that and create a new migration next.