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Page Controller

April 14, 2023 3 min read Structural Decoupling
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Name / classification

Page Controller

Intent

It is an approach of one page leading to one logical file that handles actions or requests on a website.

Explanation

Real-world example

In a shopping website, there is a signup page to register a user profile. After finishing to signup, the signup page will be redirected to a user page to show the user’s registered information.

In plain words

Page controller manages HTTP requests and data in a specific page using MVC idea. The idea is that one page contains one Controller that handles Model and View.

Programmatic Example

Here’s Signup controller when a user signup their information for a website.

 1@Slf4j
 2@Controller
 3@Component
 4public class SignupController {
 5  SignupView view = new SignupView();
 6  /**
 7   * Signup Controller can handle http request and decide which model and view use.
 8   */
 9  SignupController() {
10  }
11
12  /**
13   * Handle http GET request.
14   */
15  @GetMapping("/signup")
16  public String getSignup() {
17    return view.display();
18  }
19
20  /**
21   * Handle http POST request and access model and view.
22   */
23  @PostMapping("/signup")
24  public String create(SignupModel form, RedirectAttributes redirectAttributes) {
25    LOGGER.info(form.getName());
26    LOGGER.info(form.getEmail());
27    redirectAttributes.addAttribute("name", form.getName());
28    redirectAttributes.addAttribute("email", form.getEmail());
29    redirectAttributes.addFlashAttribute("userInfo", form);
30    return view.redirect(form);
31  }
32}

Here’s Signup model and view that are handled by Signup controller.

 1@Component
 2@Getter
 3@Setter
 4public class SignupModel {
 5  private String name;
 6  private String email;
 7  private String password;
 8  
 9  public SignupModel() {
10  }
11}

 1@Slf4j
 2public class SignupView {
 3  public SignupView() {
 4  }
 5
 6  public String display() {
 7    LOGGER.info("display signup front page");
 8    return "/signup";
 9  }
10
11  /**
12   * redirect to user page.
13   */
14  public String redirect(SignupModel form) {
15    LOGGER.info("Redirect to user page with " + "name " + form.getName() + " email " + form.getEmail());
16    return "redirect:/user";
17  }
18}

Here’s User Controller to handle Get request in a user page.

 1@Slf4j
 2@Controller
 3public class UserController {
 4  UserView view = new UserView();
 5
 6  public UserController() {}
 7
 8  /**
 9   * Handle http GET request and access view and model.
10   */
11  @GetMapping("/user")
12  public String getUserPath(SignupModel form, Model model) {
13    model.addAttribute("name", form.getName());
14    model.addAttribute("email", form.getEmail());
15    return view.display(form);
16  }
17}

Here’s User Model and View that are handled by User controller.

1@Getter
2@Setter
3public class UserModel {
4  private String name;
5  private String email;
6
7  public UserModel() {}
8}

 1@Slf4j
 2public class UserView {
 3  /**
 4   * displaying command to generate html.
 5   * @param user model content.
 6   */
 7  public String display(SignupModel user) {
 8    LOGGER.info("display user html" + " name " + user.getName() + " email " + user.getEmail());
 9    return "/user";
10  }
11}

Class diagram

alt text

Applicability

Use the Page Controller pattern when

  • you implement a site where most controller logic is simple
  • you implement a site where particular actions are handled with a particular server page

Credits