使用inversifyJS注入时无法读取未定义的属性

Question

我使用 Express 和 TypeScript 启动了一个新项目，我正在尝试使用 inversifyJS 设置 DI 容器。 它应该是非常简单的用例，有 1 个路由和控制器 到目前为止我的文件：

控制器\项目\项目.控制器

import { inject, injectable } from "inversify";

import "reflect-metadata";
import { IProjectService } from "../../services/projects/interface/IProjectService";
import { TYPES } from "../../services/projects/types";

@injectable()
class ProjectController {
  private _processService: IProjectService;

  constructor(@inject(TYPES.IProjectService) projectServicee: IProjectService) {
    this._processService = projectServicee;
  }

  public getProjects(): string {
    return this._processService.getProject();
  }
}

export { ProjectController };

服务\项目\imp\ProjectService.ts

import { injectable } from "inversify";
import "reflect-metadata";
import { IProjectService } from "../interface/IProjectService";

@injectable()
class ProjectServicee implements IProjectService {
  getProject(): string {
    return "Project A";
  }
}

@injectable()
class ProjectService implements IProjectService {
  getProject(): string {
    return "Project B";
  }
}

export { ProjectServicee, ProjectService };

服务\项目\接口\IProjectService.ts

export interface IProjectService {
  getProject(): string;
}

路线\projects.ts 在这里，我向容器询问 ProjectController 的实例并按预期获取它，但其中的 IProjectService 的私有实例在运行时未定义

import { myContainer } from "../../inversify.config";
import { ProjectController } from "../controllers/projects/projects.controller";
import { CONTROLLERS_TYPES } from "../controllers/types";

import * as express from "express";
const router = express.Router();

const pc = myContainer.get<ProjectController>(
  CONTROLLERS_TYPES.ProjectController
);

router.get("/", pc.getProjects);

export default router;

root\inversify.config.ts

import { Container } from "inversify";
import { TYPES } from "./src/services/projects/types";
import { IProjectService } from "./src/services/projects/interface/IProjectService";
import { ProjectService } from "./src/services/projects/imp/ProjectService";
import { CONTROLLERS_TYPES } from "./src/controllers/types";
import { ProjectController } from "./src/controllers/projects/projects.controller";
const myContainer = new Container();

myContainer
  .bind<ProjectController>(CONTROLLERS_TYPES.ProjectController)
  .to(ProjectController);
myContainer.bind<IProjectService>(TYPES.IProjectService).to(ProjectService);

export { myContainer };

控制器类型.ts

const CONTROLLERS_TYPES = {
  ProjectController: Symbol.for("ProjectController"),
};

export { CONTROLLERS_TYPES };

服务\项目 ypes.ts

const TYPES = {
  IProjectService: Symbol.for("IProjectService"),
};

export { TYPES };

最后是我的主要：

import projectRoutes from "./routes/projects";

import express from "express";
const app = express();

app.get("/", function (req, res) {
  res.send("Hello World");
});

app.use("/api/projects", projectRoutes);

console.log("Listening on port 3000");
app.listen(3000);

现在，当尝试调用控制器的 get 方法时，我收到错误：

Cannot read properties of undefined (reading '_processService')

这意味着控制器中 _processService 的初始化不起作用，我缺少什么？

Answer 1

不知道你解决了吗，我也遇到这个问题了。实际上我的代码中的所有实现都没有问题。

我认为当您在 router.get() 方法中传递 pc.getProjects 时，您会丢失“this”引用。

这就是为什么当路由器执行下面的方法时...

  public getProjects(): string {
    return this._processService.getProject();
  }

... this._processService 未定义。

也许尝试这样做：

router.get("/", pc.getProjects.bind(pc));

而不是：

router.get("/", pc.getProjects);

这对我有用。让我知道进展如何...

Answer 2

我有一个与此问题类似的案例，但我无法解决它，当组件中只有构造函数时我无法注入，我的代码甚至与所提供的类似。