Javascript Can'；t在动态路由中获取端口3000

目前，我正在努力从本地主机4200上提供的Angular应用程序中获取localhost:3000

• 角度版本：9.1.7

environment.ts（保存API url的位置）：

blogpost.component.ts（我遇到问题的组件）：

有关此问题的其他一些信息：

import { Component, OnInit } from "@angular/core";
import { environment } from "../../environments/environment";

@Component({
    selector: "app-blogpost",
    templateUrl: "./blogpost.component.html",
    styleUrls: [ "./blogpost.component.scss" ]
})
export class BlogpostComponent implements OnInit {
    id: string;
    postdata;

    async ngOnInit() {
        console.log(`${environment.apiURL}/api/posts/get/id/${this.id}`);
        // This console.logs http://localhost:3000/api/posts/get/id/undefined
        let req = await fetch(`${environment.apiURL}/api/posts/get/id/${this.id}`);
        // This sends a request to http://localhost:4200/api/posts/get/id/someid
        this.postdata = await req.json();
    }
}

• 我已经试过使用代理了，但不起作用

• fetch命令向其他组件上的端口3000发送请求

• 这个组件与其他组件的唯一区别在于它有一个动态路由

import { Component, OnInit } from "@angular/core";
import { environment } from "../../environments/environment";

@Component({
    selector: "app-blogpost",
    templateUrl: "./blogpost.component.html",
    styleUrls: [ "./blogpost.component.scss" ]
})
export class BlogpostComponent implements OnInit {
    id: string;
    postdata;

    async ngOnInit() {
        console.log(`${environment.apiURL}/api/posts/get/id/${this.id}`);
        // This console.logs http://localhost:3000/api/posts/get/id/undefined
        let req = await fetch(`${environment.apiURL}/api/posts/get/id/${this.id}`);
        // This sends a request to http://localhost:4200/api/posts/get/id/someid
        this.postdata = await req.json();
    }
}

import { BlogpostComponent } from "./blogpost/blogpost.component";
...
{ path: "post/:id", component: BlogpostComponent }