feature: add Page Controller pattern (#2202)

* feat: create page controller * add test * add documentation * fix: delete img file * fix: modify App, SignupMode, UserController, pom.xml, and Readme * fix: modify MVC files on page controller * fix: modify readme file
2026-05-21 08:24:40 +00:00 · 2023-01-01 19:57:30 +11:00
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+---
+title: Page Controller
+categories: Structural
+language: en
+tags:
+- Decoupling
+---
+
+## 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.
+
+```java
+@Slf4j
+@Controller
+@Component
+public class SignupController {
+  SignupView view = new SignupView();
+  /**
+   * Signup Controller can handle http request and decide which model and view use.
+   */
+  SignupController() {
+  }
+
+  /**
+   * Handle http GET request.
+   */
+  @GetMapping("/signup")
+  public String getSignup() {
+    return view.display();
+  }
+
+  /**
+   * Handle http POST request and access model and view.
+   */
+  @PostMapping("/signup")
+  public String create(SignupModel form, RedirectAttributes redirectAttributes) {
+    LOGGER.info(form.getName());
+    LOGGER.info(form.getEmail());
+    redirectAttributes.addAttribute("name", form.getName());
+    redirectAttributes.addAttribute("email", form.getEmail());
+    redirectAttributes.addFlashAttribute("userInfo", form);
+    return view.redirect(form);
+  }
+}
+```
+Here's Signup model and view that are handled by Signup controller.
+
+```java
+@Component
+@Getter
+@Setter
+public class SignupModel {
+  private String name;
+  private String email;
+  private String password;
+  
+  public SignupModel() {
+  }
+}
+```
+
+```java
+@Slf4j
+public class SignupView {
+  public SignupView() {
+  }
+
+  public String display() {
+    LOGGER.info("display signup front page");
+    return "/signup";
+  }
+
+  /**
+   * redirect to user page.
+   */
+  public String redirect(SignupModel form) {
+    LOGGER.info("Redirect to user page with " + "name " + form.getName() + " email " + form.getEmail());
+    return "redirect:/user";
+  }
+}
+```
+
+Here's User Controller to handle Get request in a user page.
+
+```java
+@Slf4j
+@Controller
+public class UserController {
+  UserView view = new UserView();
+
+  public UserController() {}
+
+  /**
+   * Handle http GET request and access view and model.
+   */
+  @GetMapping("/user")
+  public String getUserPath(SignupModel form, Model model) {
+    model.addAttribute("name", form.getName());
+    model.addAttribute("email", form.getEmail());
+    return view.display(form);
+  }
+}
+```
+
+Here's User Model and View that are handled by User controller.
+```java
+@Getter
+@Setter
+public class UserModel {
+  private String name;
+  private String email;
+
+  public UserModel() {}
+}
+```
+
+```java
+@Slf4j
+public class UserView {
+  /**
+   * displaying command to generate html.
+   * @param user model content.
+   */
+  public String display(SignupModel user) {
+    LOGGER.info("display user html" + " name " + user.getName() + " email " + user.getEmail());
+    return "/user";
+  }
+}
+```
+
+## Class diagram
+![alt text](./etc/page-controller.urm.png)
+
+## 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
+- [Page Controller](https://www.martinfowler.com/eaaCatalog/pageController.html)
+- [Pattern of Enterprise Application Architecture](https://www.martinfowler.com/books/eaa.html)