WEBVTT 00:00.020 --> 00:04.610 Okay, our response going back to postman in this case is a bit of a mess, and it's because of the 00:04.610 --> 00:09.650 way that our data is structured in our entity classes, and we should see the same response if we try 00:09.650 --> 00:10.790 and get our basket. 00:10.820 --> 00:16.910 Now what we should have that I didn't check in the previous lesson is the cookies and what we should 00:16.910 --> 00:17.960 see inside here. 00:17.960 --> 00:21.860 Although for some reason it does take a couple of times for this to appear. 00:21.860 --> 00:27.470 I need to click cookies, close it, and then click cookies again, at least on my version of postman 00:27.590 --> 00:29.840 before I actually see the basket ID. 00:29.870 --> 00:38.720 But what we have now is a cookie, and this cookie is going to go up to our API server with every request 00:38.750 --> 00:39.200 now. 00:39.200 --> 00:44.990 So if I do attempt to go and get the basket, then what we should find is that we do send up the cookie 00:44.990 --> 00:46.430 and that should return the basket. 00:46.430 --> 00:48.920 If we click send, then we do get this. 00:48.920 --> 00:54.890 And every time this changes in Net between versions, it seems what we should be seeing here is an exception, 00:54.890 --> 00:59.180 but I'm actually seeing the response with all of the properties inside there. 00:59.180 --> 01:02.840 We do see the 500 internal server error and what that should mean. 01:02.840 --> 01:11.290 If we go back to the API server then we should see the exception inside our logs here and not the response. 01:11.290 --> 01:14.950 But we can see this massive stack trace actually before it does give up. 01:14.950 --> 01:20.860 And we do see the actual exception that for some reason we're not seeing in postman, and it tells us 01:20.860 --> 01:23.470 a possible object cycle was detected. 01:23.470 --> 01:26.710 And that's because of the reasons I mentioned in the previous lesson. 01:26.710 --> 01:28.360 So how do we solve this problem then? 01:28.360 --> 01:29.560 What do we do with this? 01:29.560 --> 01:36.190 Well, we introduce something called a DTO, a data transfer object into our application. 01:36.190 --> 01:44.290 And a data transfer object is just a simple object that's used to transfer data between layers or systems 01:44.290 --> 01:45.790 in an application. 01:45.790 --> 01:51.370 And it typically only contains the data fields needed without any business logic. 01:51.370 --> 01:56.560 So effectively we're going to create an object that has the properties that we do want to return in 01:56.560 --> 01:57.100 this case. 01:57.100 --> 02:01.690 So let's go ahead and do that I'll just close things down at the top. 02:01.690 --> 02:02.800 I'll also stop the debugger. 02:02.800 --> 02:06.940 We don't need that for what we're doing now unless we run into a problem of course. 02:06.940 --> 02:12.040 And inside our API folder I'm going to create a new folder called Dtos. 02:12.070 --> 02:16.570 Inside the Dtos folder, I'm going to create a new file that's going to be a class, and I'm going to 02:16.570 --> 02:19.360 call it baskets DTO. 02:19.360 --> 02:26.980 And inside this class I'm just going to copy the basket properties that we're going to return the ID, 02:27.010 --> 02:34.690 the basket ID and the items, and I will paste it into the basket DTO. 02:36.130 --> 02:43.750 And then for the list of basket items I'm going to say basket item DTO, put my cursor in this and say 02:43.750 --> 02:50.560 generate class basket item DTO and then move this into its own file once again using the quick fix. 02:50.650 --> 02:52.930 And then I'm going to go to the basket item. 02:52.930 --> 02:58.840 And I'm going to copy the properties inside here to give us an idea of what it is we want to be returning. 02:58.840 --> 03:04.420 But this one definitely needs a bit of adjustment, so I'll just paste that in there for the time being. 03:04.420 --> 03:09.010 And then we'll come back and populate this with the correct code that we need in there. 03:09.010 --> 03:12.580 So for the basket item DTO we need the id. 03:12.610 --> 03:19.080 I'll just create a line below this and we'll have a prop Of string for the name of the products will 03:19.080 --> 03:20.100 have a prop. 03:20.100 --> 03:29.880 That's going to be a long for the price, and we'll have a prop of a string for the picture URL. 03:29.940 --> 03:39.810 We'll have another prop that's a string for the brand, another prop that is a string for the type, 03:40.890 --> 03:42.390 and that should be that. 03:42.390 --> 03:47.070 So we don't actually need these other properties live copied inside here the navigation properties can 03:47.070 --> 03:47.850 all go. 03:47.850 --> 03:55.530 And for the DTO as well we'll use the required operator or modifier inside here. 03:55.860 --> 03:58.260 So we specify that each of these are required. 03:58.260 --> 04:05.220 So I'll just copy the required there and paste it in here and not in the price. 04:05.220 --> 04:05.940 We don't need it in there. 04:05.940 --> 04:07.320 We need it in the picture URL. 04:07.320 --> 04:08.340 We need it in the brand. 04:08.370 --> 04:10.290 We need it in the type. 04:10.290 --> 04:13.260 And I'll just ignore whatever that warning is. 04:13.260 --> 04:16.410 I don't think that's a problem, but we'll soon see. 04:17.460 --> 04:22.790 So now we've got our basket item DTO and we've got our basket dito. 04:22.820 --> 04:26.090 That's returning the basket item dtos as the items. 04:26.090 --> 04:29.090 How do we use this then to solve the problem that we had? 04:29.120 --> 04:32.660 Well, let's go across to our basket controller once again. 04:32.690 --> 04:40.610 And for the short term or the very short term, instead of returning the basket here, we'll still get 04:40.610 --> 04:41.300 the basket. 04:41.300 --> 04:47.750 And that's going to include the item and the also the products, the related properties. 04:47.750 --> 04:53.780 But what we return this is where we get the problem, because our API controller attempts to format 04:53.780 --> 04:56.900 this into JSON using a JSON serializer. 04:56.900 --> 05:01.760 So to solve this problem we can say return new basket DTO instead. 05:01.760 --> 05:08.840 And we'll also need to change the return type here to basket DTO for the action result for the get basket 05:08.930 --> 05:17.000 and inside the basket DTO the new basket DTO we're going to need to supply the basket ID equal to basket 05:17.660 --> 05:19.520 dot basket ID. 05:20.210 --> 05:25.190 We'll need the items and we'll set this equal to basket dot items. 05:25.190 --> 05:31.870 And then we use the select so that we can select what we want from the items. 05:31.870 --> 05:40.930 So we'll use select and then we'll say X goes to New baskets item DTO. 05:40.930 --> 05:47.110 And then inside here we can effectively map the properties that we want to return for our basket items. 05:47.110 --> 05:52.540 So we're going to have well what I want in here is a product ID property. 05:52.540 --> 05:55.690 But I'm going to need to go back to the basket item DTO. 05:57.250 --> 06:01.990 And instead of ID here we don't need the basket item DTO. 06:02.020 --> 06:04.390 We just need the product ID for this. 06:05.680 --> 06:12.550 And back to our basket controller I'll specify the product ID and this is going to be equal to x dot 06:12.970 --> 06:13.990 product ID. 06:15.070 --> 06:21.250 And then we need the name which is going to equal x dot product dot name. 06:23.680 --> 06:28.870 And then the price is going to be x dot product dot price. 06:29.500 --> 06:34.420 Then the brand is going to be equal to x dot product dot. 06:34.450 --> 06:36.220 Not the most exciting code. 06:36.220 --> 06:38.920 This by the way this mapping type code. 06:38.920 --> 06:41.230 So we'll only do this once really. 06:41.230 --> 06:44.980 And then we'll create something more reusable that we can use. 06:44.980 --> 06:49.870 There is an approach to handle this on our behalf that I've used in other courses by the way called 06:49.870 --> 06:52.810 Automapper, but I'm not going to use that right now. 06:52.810 --> 06:57.610 It's not much mapping code that we need to write, and I just want to demonstrate how we can do this 06:57.610 --> 07:00.430 without adding a tool like Automapper. 07:00.430 --> 07:04.060 And we also need a property for the picture URL. 07:04.210 --> 07:07.900 So we'll set that equal to x dot product dot picture URL. 07:07.900 --> 07:10.810 And we also need the quantity inside here. 07:10.810 --> 07:12.700 So that's going to be x dot quantity. 07:12.730 --> 07:16.150 And then we need to specify that we want this to be output to a list. 07:16.150 --> 07:21.400 So we specify two list there and close it off with semicolon at the end. 07:21.430 --> 07:23.500 Not where I just tried to put it at the end of the list. 07:23.530 --> 07:24.520 We don't want it there. 07:24.580 --> 07:26.260 We need it at the end here. 07:26.260 --> 07:32.620 So that's our basket DTO returning the basket items inside here. 07:32.890 --> 07:38.550 Now I didn't include the ID here actually, and I think I've got it in the basket Dito. 07:38.580 --> 07:40.530 I don't need to send this ID back. 07:40.530 --> 07:42.060 We've got the basket ID. 07:42.090 --> 07:43.260 That is enough. 07:43.260 --> 07:46.860 And if I go and take a look at the basket controller, this looks fine. 07:46.860 --> 07:53.610 So what we should have and I'm going to restart the API server again I don't trust Hot Reload for this 07:53.610 --> 07:54.450 for some reason. 07:54.450 --> 07:59.100 So I'm just going to make sure this works first time and just restart the API controller. 07:59.100 --> 08:00.450 And we see a warning there. 08:00.450 --> 08:05.730 But that's only because we've got a method inside our controller that we haven't populated with code 08:05.730 --> 08:06.030 yet. 08:06.060 --> 08:07.500 The remove basket item. 08:07.500 --> 08:09.600 We don't need to worry about that for the time being. 08:09.600 --> 08:16.740 So now if I go and get the basket, what we should see this time is we get the basket with its items 08:16.740 --> 08:20.100 and we've got one item in that basket. 08:20.100 --> 08:23.820 But what we created to do that was not particularly pleasant. 08:23.820 --> 08:28.980 And I would like a better way of shaping data when we return it. 08:28.980 --> 08:35.460 So in the next lesson, we're going to take a look at a tool in our toolbox that helps us deal with 08:35.460 --> 08:38.250 repetitive code so that we don't repeat ourselves. 08:38.250 --> 08:43.650 And in the next lesson, we'll take a look at extension methods to help us do that.