如何在Tsyringe中实现单例

Question

我在实现单例时遇到了困难，因为标记为@ singleton ()的类是在每一个解析()上重新创建的。

下面是一个例子

// Foo.ts This is singleton and and must be created only once
import { injectable, singleton } from "tsyringe";

@injectable()
@singleton()
export class Foo {
  constructor() {
    console.log("Constractor of Foo");
  }
}

// Bar.ts this is Bar and should be created every time. It uses the singleton
import { inject, injectable, Lifecycle, scoped } from "tsyringe";
import { Foo } from "./Foo";

@injectable()
export class Bar {
  constructor(@inject("Foo") private foo: Foo) {
    console.log("Constractor of Bar");
  }
}

// main.ts this is resolving Bar two times.
// expected output:
// Constractor of Foo
// Constractor of Bar
// Constractor of Bar

// Actual output:
// Constractor of Foo
// Constractor of Bar
// Constractor of Foo
// Constractor of Bar

import "reflect-metadata";
import { container } from "tsyringe";
import { Bar } from "./Bar";
import { Foo } from "./Foo";

container.register("Foo", { useClass: Foo });
container.register("Bar", { useClass: Bar });

const instance = container.resolve(Bar);
const instance1 = container.resolve(Bar);

我怎样才能得到想要的行为？

Answer 1

单身人士应按以下方式登记：

container.register(
  "Foo",
  { useClass: Foo },
  { lifecycle: Lifecycle.Singleton } // <- this is important
);

Answer 2

我觉得你让你的生活变得更艰难了。我看到你所做的事情和你提出的解决方案有几处不对。下面是用于源代码装饰器的@singleton()：

function singleton<T>(): (target: constructor<T>) => void {
  return function(target: constructor<T>): void {
    injectable()(target);
    globalContainer.registerSingleton(target);
  };
}

• 首先，您不需要用@injectable()来装饰，因为注射器已经添加了@singleton()。
• 最后，如果您没有注册Foo和Bar，它们将自动注册为globalContainer.registerSingleton(target)函数中的单例(当然已经设置了{ lifecycle: Lifecycle.Singleton }选项)。