WEBVTT 00:00.000 --> 00:06.090 Okay, so we've written some code, some tedious looking code to shape the data from an entity which 00:06.090 --> 00:12.150 has given us problems when we return it due to the JSON serializer into a DTO, which obviously our 00:12.150 --> 00:14.250 JSON serializer is happy with. 00:14.280 --> 00:16.620 Now we need to use this code in a few locations. 00:16.620 --> 00:17.460 We need to use it here. 00:17.460 --> 00:22.650 Of course in the get basket method, we also need it in the add item to basket method because we are 00:22.650 --> 00:24.090 returning our basket there. 00:24.090 --> 00:29.640 Now we could use the same trick and copy our code and do the same thing there. 00:29.640 --> 00:35.100 But that's not good practice and you'll often hear the phrase do not repeat yourself. 00:35.130 --> 00:43.170 Often shortened to dry DIY, and we'll use one of our tools in our dry toolbox, which is extension 00:43.170 --> 00:49.860 methods, which helps us reduce duplicate code and create reusable code that we can use wherever we 00:49.860 --> 00:50.670 need to. 00:50.700 --> 00:56.310 So in order to create an extension method and I'm going to talk about extension methods here, and I'll 00:56.340 --> 00:59.010 explain what they are as we go and use them. 00:59.010 --> 01:03.270 Inside our API folder we're going to create a new folder called extensions. 01:03.720 --> 01:10.220 And inside this extensions folder, we're going to create a new file and we're going to call it basket. 01:10.220 --> 01:12.890 In fact we need to create a new class first of all. 01:12.890 --> 01:17.960 And then I'm just going to call it basket extensions and press return. 01:17.990 --> 01:20.180 Now an extension method. 01:20.300 --> 01:22.880 First of all we make this a static class. 01:22.880 --> 01:29.420 Because when we use an extension method we don't say new basket extensions and then get access to the 01:29.420 --> 01:31.550 code and methods inside that class. 01:31.550 --> 01:33.560 We don't want to use it that way. 01:33.590 --> 01:39.800 A static class means that we can use the methods inside here without actually creating a new instance 01:39.800 --> 01:42.320 of this basket extensions class. 01:42.320 --> 01:47.210 And inside our static class we're going to create a static method. 01:47.210 --> 01:49.370 So I'll say public static. 01:49.670 --> 01:53.030 And the next thing is what are we going to return from this. 01:53.060 --> 01:57.080 Well we want to return a basket DTO from this extension method. 01:57.080 --> 01:59.690 And I'm going to call it to DTO. 01:59.690 --> 02:05.720 And what we're going to use this extension method on is our basket entity. 02:05.720 --> 02:14.480 So we specify list the keyword lists and then baskets Gets from API entities, as this is where we want 02:14.480 --> 02:17.210 to use this extension method. 02:17.210 --> 02:22.970 So our basket, when we have a basket, we will be able to say and I'll just put it in a comment. 02:22.970 --> 02:29.840 After this we will be able to say basket to DTO because we're effectively creating an extension to the 02:29.840 --> 02:35.000 basket, an extension method that extends the basket entity functionality. 02:35.000 --> 02:42.020 And one of its methods after we've done this will be to use this two DTO method. 02:42.020 --> 02:45.020 So we'll call this baskets. 02:45.020 --> 02:52.190 And inside here we will effectively return a new basket DTO. 02:52.190 --> 02:56.450 And if we go back to our basket controller what we've already got the code inside here. 02:56.450 --> 03:04.160 So I'm just going to cut this from the basket controller and paste it into our basket extensions. 03:04.250 --> 03:07.850 So when we use this method it returns the basket DTO. 03:07.880 --> 03:08.570 Great. 03:08.570 --> 03:14.690 And if we go back to our basket controller how we use this is we're going to return the basket. 03:14.780 --> 03:22.460 And notice now that we have a two DTO method available that we can use that we get from API extensions. 03:22.460 --> 03:24.350 So we'll just utilize that. 03:24.350 --> 03:26.960 And now we have much cleaner code. 03:26.960 --> 03:32.150 And this is reusable because I can also use it in the add item to basket. 03:32.150 --> 03:40.880 And where we're returning the basket we can specify basket to DTO and execute that and what we could 03:40.880 --> 03:41.450 do as well. 03:41.450 --> 03:45.530 We're not doing it at the moment because I did imply that we were not going to return the basket. 03:45.560 --> 03:51.650 We could also give this a return type as well, although it doesn't really do very much for us because 03:51.650 --> 03:55.700 we're returning this inside an HTTP response object. 03:55.700 --> 03:57.680 So we're not going to get type safety. 03:57.680 --> 03:58.700 So it's a bit pointless. 03:58.700 --> 04:05.360 But just because I've mentioned it, we could also specify that we're returning a basket DTO from this 04:05.360 --> 04:06.290 method as well. 04:06.290 --> 04:08.540 But it doesn't do anything for us. 04:08.540 --> 04:10.640 But it doesn't cause us a problem either. 04:10.640 --> 04:14.480 And when I say it doesn't do anything for us, well, it does a little bit because we can instantly 04:14.480 --> 04:20.240 look at this method and see now what it is we're returning from this method without looking down in 04:20.240 --> 04:23.300 the code to take a look at this return statement. 04:23.300 --> 04:25.190 So does this fix our problem? 04:25.190 --> 04:26.390 Well, let's open up the terminal. 04:26.390 --> 04:31.670 First of all, because we may need to restart our API controller or our API server. 04:31.670 --> 04:35.930 So I'm going to say yes to that and wait for this to restart. 04:35.930 --> 04:39.740 And let's go back across to postman. 04:39.740 --> 04:42.200 And we'll click the send to get the baskets. 04:42.200 --> 04:44.870 And this functionality is still working. 04:44.870 --> 04:47.360 Let's try and add another item to the basket. 04:47.360 --> 04:53.180 And I'm just going to repeat the same request because what they should do is increase the quantity to 04:53.210 --> 04:53.540 two. 04:53.570 --> 04:54.740 So I'll click send. 04:54.740 --> 04:58.220 And what we get back is the shaped data. 04:58.220 --> 05:00.050 We can see the quantity is two. 05:00.080 --> 05:04.760 And if I send another request to add another product for instance and click send. 05:04.760 --> 05:07.850 So I'm changing it to product ID of three and click send. 05:07.880 --> 05:13.940 Now we have two products two items in our basket, one with a quantity of two and one with a quantity 05:13.940 --> 05:14.900 of one. 05:15.170 --> 05:16.070 Perfect. 05:16.070 --> 05:21.200 And if we go and get a basket, we should see the updated basket there because we're sending our cookie 05:21.200 --> 05:23.000 to and from our API server. 05:23.000 --> 05:28.220 So just to confirm that as well because you don't see a lot of detail in this postman window. 05:28.220 --> 05:34.100 If we do, open up the console and let's just clear this because it's very busy. 05:34.100 --> 05:36.680 And I'll click send again just to get the basket. 05:36.680 --> 05:39.230 And I click on this request. 05:39.260 --> 05:41.120 Do not worry about this warning. 05:41.150 --> 05:46.010 Unable to verify the first certificate because dotnet uses a self-signed certificate. 05:46.010 --> 05:49.970 So postman is unable to verify that this is a valid certificate. 05:50.000 --> 05:55.520 A self-signed certificate is never valid, certainly not in the big bad world of the internet, but 05:55.520 --> 05:59.840 we do use it in a developer environment, so self-signed is fine and we do not need to worry about that 05:59.870 --> 06:00.500 warning. 06:00.500 --> 06:02.840 If we go and take a look at the request headers. 06:02.840 --> 06:08.810 What we can see inside here is that we are sending up that cookie with this request, and that is how 06:08.810 --> 06:13.220 we're able to get our baskets from our API server. 06:14.210 --> 06:19.220 So please do use this postman console, another tool in the toolbox for troubleshooting. 06:19.220 --> 06:24.470 And if you're not getting your basket back, then you would definitely want to come in here and see 06:24.470 --> 06:26.180 what you're using for the basket ID. 06:26.210 --> 06:30.260 Does that match the property you're using in your API, for example. 06:30.260 --> 06:34.760 So please do use all of the tools available when you encounter a problem. 06:34.760 --> 06:37.970 And the console in postman is another good one to use. 06:38.000 --> 06:45.350 Okay, so now we've got our extension method set up and we have a bit more work to do in our controller. 06:45.980 --> 06:52.310 And if we go and take a look at what we currently have for our delete method, then this is what we 06:52.310 --> 06:53.300 need to populate. 06:53.300 --> 06:59.600 So what I'd suggest is you pause the video at this stage and just populate this and see if you can get 06:59.600 --> 07:05.240 this to work and use the postman request to remove an item from the basket. 07:05.240 --> 07:09.800 And I would suggest changing this quantity from 4 to 1, for example. 07:09.800 --> 07:16.790 So you remove one of the product IDs of two and a quantity of one, and see if you can get that functionality 07:16.790 --> 07:17.900 to work. 07:18.530 --> 07:23.720 Before you take a look at the next lesson, I am going to go through this step by step in the next lesson, 07:23.720 --> 07:29.150 but I think you should be okay with getting this one completed without seeing that lesson. 07:29.150 --> 07:30.560 So please give that a go. 07:30.560 --> 07:35.090 And like I mentioned in the next lesson, I'm going to cover what we need to do for that anyway.