WEBVTT 00:00.000 --> 00:05.790 Okay, hopefully you took a look at these methods and saw how far you could get with creating the logic 00:05.790 --> 00:06.480 inside here. 00:06.480 --> 00:07.620 I'm going to go through this anyway. 00:07.620 --> 00:12.660 The idea of that was just to get you to have a think about what we might need to do, and maybe give 00:12.660 --> 00:14.010 it a go as well. 00:14.010 --> 00:16.020 The create basket, all that part. 00:16.050 --> 00:18.240 We haven't really covered what we're going to do with that. 00:18.240 --> 00:23.040 So in terms of returning the cookie etc.. 00:23.040 --> 00:25.650 So we'll cover all of that in this lesson anyway. 00:25.650 --> 00:28.080 So the first step is to get the basket. 00:28.080 --> 00:33.600 And we've got a couple of items here where we need to get the basket for the add and remove items. 00:33.600 --> 00:37.740 So we'll make this a reusable method. 00:37.740 --> 00:44.610 So I'm going to say var basket equals and I'll just say retrieve basket as the name of the method. 00:44.610 --> 00:50.040 And this is going to need to be an async method because we're going to make a call to our database. 00:50.040 --> 00:52.410 So I'll use await inside there as well. 00:52.410 --> 00:57.810 Now we don't need any parameters or arguments for this method because we're going to get the basket 00:57.990 --> 00:59.760 from the cookies. 00:59.760 --> 01:05.540 So I'm just going to put my cursor inside there and generate the method to do this, and I don't like 01:05.540 --> 01:06.260 its position there. 01:06.260 --> 01:10.400 I'm just going to cut this and put it below the delete method. 01:11.150 --> 01:19.010 So inside this method then to retrieve the baskets we are going to return a basket from this. 01:19.010 --> 01:20.810 So I'm going to specify task. 01:20.810 --> 01:23.900 And inside the task I'm going to specify basket. 01:24.140 --> 01:26.900 But we may or may not have the basket from this. 01:26.900 --> 01:31.520 So I'm going to make it optional so that we can return null from this particular method. 01:31.520 --> 01:36.230 And then we'll just check for the existence of the basket in the method where we use it. 01:36.230 --> 01:42.620 So from here we're going to return await and context dot baskets. 01:42.710 --> 01:45.410 And we need to include the items. 01:45.410 --> 01:48.380 So I'll say x goes to x dot items. 01:48.410 --> 01:53.900 And we'll use let include and say x goes to x dot products. 01:54.260 --> 01:57.620 And then we'll use first or default async. 01:57.770 --> 02:01.160 And we'll specify x goes to x dot baskets id. 02:01.190 --> 02:10.910 That's equal to the request Dough cookies, and in square brackets we're going to have the basket ID 02:11.390 --> 02:13.880 pretty much the same method we used above actually. 02:13.880 --> 02:19.670 So we can also in this case use the same method here. 02:19.670 --> 02:26.900 And instead of using all of that, we can just use a weight and retrieve baskets up here as well. 02:26.900 --> 02:29.690 And then take this line and copy it. 02:29.690 --> 02:34.370 And well we've already got it in the add item to basket. 02:34.370 --> 02:38.720 And then we can go back down to our add item to basket. 02:38.720 --> 02:41.810 So we need to check to see if we have a basket. 02:41.810 --> 02:45.830 And if we do not we're going to need a method to create a basket. 02:45.830 --> 02:48.620 So we can use an if statement here. 02:48.620 --> 02:53.090 And we can check to see if the basket is equal to null and then create the basket. 02:53.090 --> 02:56.690 But I just want to demonstrate another shorthand way of doing such a thing. 02:56.690 --> 02:58.580 So we can specify basket. 02:58.580 --> 03:03.800 And then we can use double question mark which will check it for null. 03:03.800 --> 03:10.460 And if it is null then we can assign In basket to a method that will call create basket. 03:10.460 --> 03:13.880 And what we return from this is going to be a new basket. 03:13.880 --> 03:19.430 So if the basket is null, then we're going to set it equal to what this returns, which is what we're 03:19.430 --> 03:20.270 about to create now. 03:20.270 --> 03:23.480 So I'll just put my cursor inside this method and generate the method. 03:23.480 --> 03:29.330 And then once again I'm just going to cut this and reposition it below the endpoints. 03:29.330 --> 03:34.850 So we've got our methods for the logic separate at the bottom here. 03:34.880 --> 03:38.870 Now this one has automatically generated the question mark there. 03:38.870 --> 03:41.600 But we do not want to return null from this. 03:41.600 --> 03:43.490 We do want to return the basket from this. 03:43.490 --> 03:47.360 We want to ensure it has been created when we do this. 03:48.410 --> 03:52.070 So inside this method we will create a basket ID. 03:52.130 --> 03:54.620 So I'm going to say var basket id equals. 03:54.620 --> 04:00.680 And we can use Guid and then say new guides and open parentheses. 04:00.680 --> 04:05.660 And because we want this to be a string instead of a Guid object, then we're going to use the two string 04:05.660 --> 04:07.610 method on this. 04:08.180 --> 04:13.070 And we're going to create some cookie options because we are going to return this as a cookie. 04:13.100 --> 04:20.210 So I'll say var cookie options equals new cookie options. 04:20.210 --> 04:24.980 And inside here we're going to specify that this cookie is essential. 04:24.980 --> 04:31.250 And we're going to say true because users have the ability to turn off cookies or something along those 04:31.250 --> 04:31.700 lines. 04:31.700 --> 04:38.270 And we want to say hey, for this particular cookie it's essential to the operation of our application. 04:38.270 --> 04:41.420 And basket functionality is essential. 04:41.420 --> 04:47.240 So even if when they see that cookie banner, which is quite prevalent nowadays in many websites and 04:47.240 --> 04:53.990 they say, no, I don't want any cookies going on, this one would still be usable inside the application, 04:53.990 --> 05:00.320 and we're going to give it an expires property equal to date time dot now. 05:00.320 --> 05:06.290 Or let's use UTC now in our application to be consistent with the date times, no matter where it is 05:06.290 --> 05:12.860 in the world, UTC is a standard time zone for the entire planet, so we'll use that rather than the 05:12.860 --> 05:15.350 local version, which would be datetime.now. 05:15.350 --> 05:21.590 And then we'll specify add days and we'll just pick an arbitrary number of 30 for this, that that's 05:21.590 --> 05:24.950 how long this cookie is going to survive for in the user's browser. 05:24.950 --> 05:30.110 If they don't do anything to update it, then we're going to specify response. 05:30.110 --> 05:33.710 So we do something with our HTTP request response. 05:33.710 --> 05:37.310 We're going to say response dot cookies dot append. 05:37.310 --> 05:43.910 And we're going to specify baskets id and then pass in the basket ID. 05:44.150 --> 05:47.990 And then as a third parameter we're going to pass in the cookie options. 05:48.080 --> 05:51.260 Now here once again is your string warning. 05:51.260 --> 05:55.160 Because strings are easy to make mistakes with. 05:55.160 --> 05:56.900 And we don't get any compiler warning. 05:56.900 --> 06:02.720 So please do double check your usage of basket ID and ensure it matches everywhere else we've used it 06:02.720 --> 06:03.980 inside here. 06:04.280 --> 06:10.580 Following this we can specify var baskets equals new basket. 06:12.680 --> 06:19.640 And all we need to do when we create a new basket is provide the basket ID and set it to the basket 06:19.640 --> 06:21.560 ID we've created above. 06:22.400 --> 06:27.200 And we're not getting any warnings here, which means we have met the requirements for creating a new 06:27.200 --> 06:28.130 basket. 06:28.160 --> 06:32.930 Following that, we can tell Entity Framework to start tracking this basket. 06:32.930 --> 06:39.620 And the way that we do that, we say context dot baskets, dot ads and pass in basket. 06:39.620 --> 06:44.090 And then we can return the baskets from this method. 06:44.120 --> 06:46.550 So at this point we're doing nothing with the database. 06:46.550 --> 06:51.260 We're simply asking Entity Framework to track this new basket in memory. 06:51.290 --> 06:58.730 And if we go back up to our ad basket item then now our basket is either the one we've got from our 06:58.730 --> 07:02.240 database or it's the one that we've just created. 07:02.270 --> 07:06.050 So then we need to go and get the product that we want to add. 07:06.050 --> 07:07.730 And we've got the product ID here. 07:07.730 --> 07:18.610 So let's go to the database again and we'll specify var product equals Awaits and context dot products. 07:18.610 --> 07:24.100 And for this one, because we want to get the product by its primary key, effectively, we can actually 07:24.100 --> 07:27.100 use the find async method. 07:27.100 --> 07:34.120 This particular method in Entity Framework only will find an entity with the given primary key values. 07:34.120 --> 07:39.790 If we want to get an entity based on one of its other properties, then we have to use Firstordefault 07:39.790 --> 07:46.630 or single or default, but we can use find async if we do know the primary key ID of that entity. 07:46.630 --> 07:50.380 So we can use the product ID inside here to find it. 07:50.410 --> 07:54.340 Now we have no guarantee that that product exists in the database. 07:54.340 --> 07:56.020 So this product could be null. 07:56.020 --> 07:58.750 So we need to check at this point. 07:58.750 --> 08:03.100 And we'll check to see if the product is equal to null. 08:03.340 --> 08:07.420 And if so then we're going to return a bad request at this point. 08:07.420 --> 08:15.610 And we're just going to say problem adding basket to or problem adding item to basket would make more 08:15.610 --> 08:17.260 grammatical sense. 08:19.360 --> 08:24.460 So with in the last section, we've dealt with handling HTTP response errors. 08:24.460 --> 08:28.450 And we know what's going to happen if we do return a bad request. 08:28.450 --> 08:33.970 At this point, that's going to pop up a toast to the user to notify them that there was an issue with 08:33.970 --> 08:38.920 trying to add this item, because if we don't have the product in the database, we cannot add it to 08:38.950 --> 08:39.760 our basket. 08:39.790 --> 08:44.560 Of course, the next step then is to add the item to the basket. 08:44.560 --> 08:48.460 And we created a method inside our entity to do this. 08:48.460 --> 08:50.830 So we can specify basket add item. 08:50.830 --> 08:52.810 And this takes two parameters. 08:52.810 --> 08:56.080 It takes the product and it takes the quantity. 08:56.110 --> 09:00.610 So we can pass in the product and the quantity inside there. 09:00.640 --> 09:07.840 And then in order to update our database we do need to save our changes into the database. 09:07.840 --> 09:12.970 So we're going to check this as well to make sure that something has been updated in our database. 09:12.970 --> 09:20.500 So we'll use var result then say await context and save changes Is a sink. 09:20.500 --> 09:27.010 So all of the changes that have been saved in memory, perhaps we've got a new basket that we're creating. 09:27.130 --> 09:30.340 Perhaps we've added something to that basket. 09:31.120 --> 09:36.190 Then all of those changes get saved inside this method. 09:36.220 --> 09:42.940 Now, the way that this works with our Dbcontext and Entity Framework, I mentioned earlier that this 09:42.940 --> 09:44.050 uses a couple of patterns. 09:44.050 --> 09:47.350 It uses a repository pattern and a unit of work pattern. 09:47.350 --> 09:55.030 And the idea, the big idea with the unit of work pattern is that all of our changes are tracked. 09:55.750 --> 10:01.630 And then if one of those changes fails, then they all fail and everything gets rolled back to the state 10:01.630 --> 10:04.660 that it was in before we started making changes. 10:05.320 --> 10:09.970 But if they all succeed, then this save changes method will succeed. 10:10.000 --> 10:18.190 So everything inside here is effectively a transaction and transactions. 10:18.220 --> 10:22.150 Either all the changes have to succeed or none of them succeed. 10:22.150 --> 10:27.400 and that's what we really try and achieve when using the unit of work pattern. 10:27.400 --> 10:34.450 But that's already included with Entity Framework and that dbcontext then we can check the results. 10:34.450 --> 10:39.010 And the results, by the way, is going to be an integer. 10:39.010 --> 10:44.080 If we take a look at what this actually returns, then this returns an int. 10:44.110 --> 10:49.210 And this int represents the number of changes that were made into our database. 10:49.210 --> 10:54.970 So all we need to do to check that something is changed in our database is just make sure that number 10:54.970 --> 10:57.790 of changes is greater than zero. 10:57.790 --> 11:04.000 It doesn't matter if it's one, two, five, 50 changes based on what I was saying earlier, if one 11:04.000 --> 11:05.710 change fails, they all fail. 11:05.710 --> 11:10.240 Then we only care if more than zero changes have occurred in our database. 11:10.240 --> 11:16.840 So this will result in true if the changes are greater than zero. 11:16.930 --> 11:19.180 So we can specify if results. 11:19.180 --> 11:25.720 And we're effectively checking to make sure the boolean is equal to true if we just say result that 11:25.720 --> 11:28.720 is effectively equal to saying this. 11:28.720 --> 11:31.390 But we don't need to specify double equals true. 11:31.390 --> 11:43.240 There we can return a created at action result that's going to return to us a 201 and a created action 11:43.240 --> 11:48.190 results will return the thing that we're going to return. 11:48.190 --> 11:52.810 I did mention we're not going to return the basket earlier, but I think we will return the basket as 11:52.810 --> 11:57.610 well at this stage, even though our client doesn't actually need it, because we can handle the changes 11:57.610 --> 11:59.050 locally on the client. 11:59.050 --> 12:04.450 For this example, whilst we're developing our API, I think I am going to return the basket as well. 12:04.450 --> 12:05.860 So the created an action. 12:05.860 --> 12:11.860 It also returns a location header of how to get the thing that's been updated or added. 12:11.860 --> 12:18.730 So we want in this case we want to return the get basket and we return a location header with the response 12:18.730 --> 12:23.080 which will take a look at when we test this in postman of where to get the basket from. 12:23.080 --> 12:28.120 So that's going to be localhost 5001 API forward slash basket. 12:28.630 --> 12:30.700 And that would retrieve the basket. 12:30.700 --> 12:33.880 And that's the location header we want to send back with this response. 12:33.910 --> 12:38.800 Don't worry if that's not 100% clear because it will be once we test this method. 12:38.830 --> 12:40.750 So we give it a name of get basket. 12:40.750 --> 12:47.380 This is the action when we say created an action, this is the action that contains the location, the 12:47.380 --> 12:50.860 endpoint of how to get the basket that has been updated. 12:50.890 --> 12:55.420 And then in the second parameter, we can just pass in the basket as the thing that we are going to 12:55.420 --> 12:56.230 return. 12:56.350 --> 13:06.790 Now if results is false and not true, then we will return a bad request because we didn't save the 13:06.790 --> 13:08.440 changes into the database. 13:08.440 --> 13:13.390 And I'm just going to say problem updating basket for this one. 13:13.450 --> 13:18.220 So now that we've got something some logic in our code and we've got our controller endpoint, what 13:18.220 --> 13:23.170 we'll do is we'll take a look at this through the debugger next so that we can see what's going on as 13:23.200 --> 13:26.350 we're adding an item into our basket. 13:26.680 --> 13:29.380 And we'll take a look at that next.