1 00:00:01,670 --> 00:00:05,990 In the previous step, we returned a hard-coded string back. 2 00:00:06,110 --> 00:00:11,990 We mapped GET request to this URI, to this method which was returning a simple string. In this 3 00:00:11,990 --> 00:00:19,400 step, we would actually create an object for hello-world-bean and try to return that back and see what 4 00:00:19,400 --> 00:00:20,810 would happen. 5 00:00:20,840 --> 00:00:24,590 One of the things you need to understand is the fact, there is a lot of things that are happening in 6 00:00:24,590 --> 00:00:25,690 the background. 7 00:00:25,700 --> 00:00:30,330 We used Spring Boot to create the project. Through the spring-boot-starter-projects, 8 00:00:30,350 --> 00:00:34,520 we are using frameworks like Spring, Spring MVC, and a lot of other things. 9 00:00:34,520 --> 00:00:37,220 So, there is a lot of magic which is happening in the background. 10 00:00:37,430 --> 00:00:44,270 Before we get there, we would focus on getting another simple GET request working. So, I would copy this 11 00:00:44,510 --> 00:00:45,320 method. 12 00:00:45,320 --> 00:00:46,590 There would be a compilation error. 13 00:00:46,640 --> 00:00:48,520 Let's not worry about it right now. 14 00:00:48,620 --> 00:00:53,710 What I want to do is to create a GetMapping to hello-world 15 00:00:53,960 --> 00:00:58,970 and this time I would want to create a bean and return it back. 16 00:00:58,970 --> 00:01:04,840 So, instead of creating a simple string, I would want to create a bean and return it back. The URI 17 00:01:04,840 --> 00:01:05,370 I would want to 18 00:01:05,380 --> 00:01:10,260 map is hello-world-bean. We would continue mapping the GetMapping request. 19 00:01:10,700 --> 00:01:15,500 However, instead of returning a string, we want to return a bean back. How do we do that? Let's quickly do that. 20 00:01:15,860 --> 00:01:16,700 So, we want to do 21 00:01:16,760 --> 00:01:18,060 hello-world-bean 22 00:01:18,080 --> 00:01:21,690 and I'll make the change in the method name. 23 00:01:21,690 --> 00:01:28,790 Now, you'd see that the entire thing compiles but instead of creating Hello World, what I would want 24 00:01:28,790 --> 00:01:31,670 to do is, to create a HelloWorld 25 00:01:31,920 --> 00:01:36,980 Bean. One more thing I'd want to do is, to make sure that this method is returning a Hello World Bean. 26 00:01:37,270 --> 00:01:38,060 So, instead of string, 27 00:01:38,060 --> 00:01:39,020 we want to return a 28 00:01:39,170 --> 00:01:39,820 Hello World 29 00:01:39,840 --> 00:01:42,510 Bean. Actually, the HelloWorldBean is not really there. 30 00:01:42,590 --> 00:01:49,120 So, let's go ahead and create that first. How do I create it? Control 1 or Command 1 and create class 31 00:01:49,190 --> 00:01:50,290 HelloWorldBean. 32 00:01:50,360 --> 00:01:51,570 Let's do that. 33 00:01:52,010 --> 00:01:52,550 HelloWorld 34 00:01:52,550 --> 00:01:53,260 Bean. 35 00:01:53,450 --> 00:01:58,440 I'll take the default and click Finish and I would want to create, next, 36 00:01:58,520 --> 00:02:03,800 if you'd see, there is a constructor which is present in here. So, let's go ahead and do a Control 1 and 37 00:02:03,800 --> 00:02:04,880 create constructor 38 00:02:04,880 --> 00:02:10,510 HelloWorld. I'd want to create a HelloWorldBean with a message. 39 00:02:10,730 --> 00:02:17,270 What I want to do with is, this.message = message. 40 00:02:17,300 --> 00:02:19,190 Now, I would get another compilation error. 41 00:02:19,190 --> 00:02:22,730 Now, I press Control 1 and I'm going to create a message in here. 42 00:02:22,730 --> 00:02:25,100 So, we have a private field called message. 43 00:02:25,100 --> 00:02:32,660 We have a Hello Bean accepting that in the constructor and setting it to itself. Let's create a Getter, sorry a setter 44 00:02:32,690 --> 00:02:34,100 quickly. 45 00:02:34,100 --> 00:02:35,580 So, I'll say, Select Setters. 46 00:02:35,760 --> 00:02:36,440 OK. 47 00:02:36,530 --> 00:02:44,030 The easiest way to do that is right-click, Source and you can go and select Generate Getters and Setters. 48 00:02:44,060 --> 00:02:49,860 So, I generated setter and obviously, I would also want to generate a toString(). 49 00:02:49,880 --> 00:02:56,960 So, let's generate a toString() as well. Right-click, Source, Generate toString(), I'll say, OK. So, we're creating 50 00:02:56,960 --> 00:02:59,050 a very simple bean, nothing complex in here. 51 00:02:59,120 --> 00:03:04,820 So, we're just creating a simple bean and now our HelloWorldController would compile 52 00:03:04,820 --> 00:03:05,270 fine. 53 00:03:05,750 --> 00:03:12,650 So, what we have done until now is very simple, right. We have defined a simple HelloWorldBean which accepts a message 54 00:03:12,980 --> 00:03:16,840 and we are actually returning it back in the controller method. 55 00:03:16,850 --> 00:03:18,470 Let's start the application up. 56 00:03:18,620 --> 00:03:20,170 Let's go to URI, 57 00:03:20,300 --> 00:03:22,670 hello-world-bean. 58 00:03:22,980 --> 00:03:25,570 You would see that there is an error. 59 00:03:25,680 --> 00:03:27,740 It was an unexpected error. 60 00:03:27,770 --> 00:03:30,820 No converter found for return value of type 61 00:03:30,870 --> 00:03:31,580 HelloWorldBean. 62 00:03:31,590 --> 00:03:35,450 This is one of the important things that you'd need to understand. 63 00:03:35,450 --> 00:03:41,700 Actually, it is not really a easy error to debug and that is the reason why I illustrated this first step. 64 00:03:41,700 --> 00:03:45,690 So, this HelloWorldBean does not have a Getter. 65 00:03:46,220 --> 00:03:51,350 So, if we don't create a Getter, then the automatic conversion will not work. 66 00:03:51,350 --> 00:03:53,120 So, let's go out and create the Getter. 67 00:03:53,300 --> 00:04:01,120 So, right-click, Source, Generate Getters and Setters, and select the Getter for that 68 00:04:01,130 --> 00:04:04,990 and now, you'd see that the Getter is present in here. 69 00:04:05,030 --> 00:04:07,240 Let's quickly restart the application. 70 00:04:07,240 --> 00:04:11,900 And now, if you launched the HelloWorldBean, you would see a JSON message back. 71 00:04:11,900 --> 00:04:14,890 You'd see that message: "Hello World". 72 00:04:14,960 --> 00:04:19,250 You can see that this message is adhering to a JSON structure. 73 00:04:19,290 --> 00:04:21,350 We're calling this GET URI 74 00:04:21,890 --> 00:04:26,450 and the HelloWorldBean is being returned with the value Hello World. 75 00:04:26,780 --> 00:04:31,530 And if you look at the structure, it's actually reflecting this structure in here. 76 00:04:31,710 --> 00:04:35,860 So, it's just returning message and Hello World. 77 00:04:35,960 --> 00:04:38,070 The name of the field here is message. 78 00:04:38,120 --> 00:04:39,520 So, that's exactly what is here 79 00:04:39,740 --> 00:04:46,030 and the text which is being set to the message is being presented as its value 80 00:04:46,070 --> 00:04:53,110 and this coming back as a JSON string. In this step, we added in one more simple method. 81 00:04:53,110 --> 00:04:55,870 However, this is returning a bean back. 82 00:04:56,000 --> 00:04:58,220 Earlier, we returned a simple string back. 83 00:04:58,220 --> 00:05:04,410 Now, we are returning a bean back and this bean is being automatically converted into JSON and returned 84 00:05:04,410 --> 00:05:08,020 back. The first two steps were really simple, right. 85 00:05:08,030 --> 00:05:14,100 We just created a couple of simple methods. In the next step, we will understand what's happening in the 86 00:05:14,100 --> 00:05:16,950 background of these two steps. 87 00:05:17,460 --> 00:05:20,580 How is the request being handled, 88 00:05:20,580 --> 00:05:22,180 who is handling the request, 89 00:05:22,290 --> 00:05:26,820 and also, how is the HelloWorldBean content getting translated to a JSON. 90 00:05:27,150 --> 00:05:29,880 We'll look at all that in the next step.