如何在MVC架构中防止上帝模型class？

Question

如何防止他们的模型类变得太大或依赖于与他们没有直接关系的对象？

例子

想象一个用户注册表，一旦成功注册，用户就会收到一封电子邮件来验证他们的电子邮件地址。

示例代码1

免责声明 - 这是演示代码

// route.js

app.post('/register', (req, res) => {
  container.get('UserController').postRegisterUser(req, res);
});

选项 1 - 在用户模型中添加 emailSender 依赖项

// userController.js

class UserController {
  public constructor(model) {
    this.model = model;
  }

  public postRegisterUser(req, res) {
    const {email, password, repeatPassword} = req.body;
    const user = this.model.registerUser({email, password, repeatPassword});
    return res.render('/', user);
  }
}

// UserModel.ts

class UserModel {
  constructor(repository, validator, emailSender) {
    this.repository = repository;
    this.validator = validator;
    this.emailSender = emailSender;  // <--- emailSender injected in to model
  }

  public registerUser(user) {
    if (this.validator.isValid(user)) {
      this.repository.save(user);

      this.emailSender.sendVerificationEmail(user.email); // <---- emailSender called here

      return user;
    }
  }
}

选项 2 - 在控制器中添加 emailSender 依赖项

// userController.js

class UserController {
  public constructor(model, emailSender) {
    this.model = model;
    this.emailSender = emailSender;  // <--- Injected in constructor
  }

  public postRegisterUser(req, res) {
    const {email, password, repeatPassword} = req.body;
    const user = this.model.registerUser({email, password, repeatPassword});

    this.emailSender.sendVerificationEmail(email); // <--- emailSender called here

    return res.render('/', user);
  }
}

// UserModel.ts

// no EmailSender injected
class UserModel {
  constructor(repository, validator) {
    this.repository = repository;
    this.validator = validator;
  }

  public registerUser(user) {
    if (this.validator.isValid(user)) {
      this.repository.save(user);
      return user;
    }
  }
}

可以看到当涉及其他系统时这些依赖性会变得有多大——例如将数据发送到 S3 存储桶、生成 csv 文件等。理想情况下我不希望我的控制器或模型具有这些依赖性，但他们去哪儿了？

我想理想的解决方案是介于上述两个选项之间的东西。我只是对如何实施我的 Web 应用程序有困难。

Answer 1

您可以构建另一个组件 UserProcessor 或 UserRegistrationProcessor，其中包含对其他服务的所有外部调用，并将该组件注入 UserController。

如何在MVC架构中防止上帝模型class？

How to prevent a God model class in an MVC architecture?

architecture

model-view-controller

dependency-injection

software-design

node.js