InversifyJS未在嵌套类中插入依赖项

Question

我正在尝试在我的typescript应用程序中使用InversifyJS进行依赖注入。当我按照文档中给出的简单示例操作时，一切都运行得很好。但是，依赖项不会被注入到依赖链中较低的类中。希望这个例子能让我想说的更清楚。我删除了尽可能多的样板文件：

EmployeeFactory.ts

@injectable()
class EmployeeFactory {
    create(employeeName: string): Employee {
        /*
         * I think my error comes from the use of
         * the new keyword right here. Not sure though.
         */
        return new Employee(employeeName);
    }
}

Company.ts

@injectable()
class Company {
    @inject('EmployeeFactory') private employeeFactory: EmployeeFactory;

    public getEmployees() {
        return [
            this.employeeFactory.create('Alice'),
            this.employeeFactory.create('Bob')
        ]
    }

}

Employee.ts

@injectable()
class Employee  {
    @inject('EmployeeFactory') private employeeFactory: EmployeeFactory;
    constructor(readonly name: string) {

    }

    public getBoss(): Employee {
        //TypeError: Cannot read property 'create' of undefined
        return this.employeeFactory.create("Boss man")
    }
}

然后这是我运行以获取错误的代码

import { Container } from "inversify";

let myContainer = new Container();
myContainer.bind<EmployeeFactory>("EmployeeFactory").to(EmployeeFactory);
myContainer.bind<Company>('Company').to(Company);
myContainer.bind<Employee>('Employee').to(Employee);

let oscorp: Company = myContainer.get<Company>('Company');

let employees: Employee[] = oscorp.getEmployees();
console.log('employees', employees);
// PRINTS: employees [ Employee { name: 'Alice' }, Employee { name: 'Bob' } ]

let boss = employees[0].getBoss(); 
console.log('boss', boss);

所以我的问题是:在我的应用程序中没有"myContainer“的情况下，如何将EmployeeFactory注入Employee类？我确信我错过了关于InversifyJS的一些重要的东西，所以任何帮助都是感激不尽的。

Answer 1

这里的问题是，类Employee只使用操作符new创建，而不是使用inversifyJS创建。因此，您只需通过JS创建新实例，而无需任何依赖注入。

如果只想让代码正常工作，只需将代码重写为smth即可，如下所示

EmployeeFactory.ts

@injectable()
class EmployeeFactory {
    create = (employeeName: string): Employee => {
        return new Employee(this, employeeName);
    }
}

Employee.ts

@injectable()
class Employee  {
    constructor(
        private _employeeFactory: EmployeeFactory,
        readonly name: string,
    ) {}

    public getBoss(): Employee {
        return this._employeeFactory.create("Boss man")
    }
}

但是如果你想让它倒置，那么你需要使用工厂注入：https://github.com/inversify/InversifyJS/blob/master/wiki/factory_injection.md

然后，需要将绑定中的代码更改为

myContainer.bind<Company>('Company').to(Company);
myContainer.bind<Employee>('Employee').toConstructor(Employee);
container.bind<interfaces.Factory<Employee>>('Factory<Employee>').toFactory<Employee>((context: interfaces.Context) => {
    return (name: string) => {
        const EmployeeConstructor = context.container.get<Employee>('Employee');
        return new EmployeeConstructor(name);
    };
});

Company.ts

@injectable()
class Company {
    @inject('Factory<Employee>') private employeeFactory: (name: string) => Employee;

    public getEmployees() {
        return [
            this.employeeFactory('Alice'),
            this.employeeFactory('Bob')
        ]
    }

}