Header 未赋值

Question

这是我的代码

import { HttpClient, HttpHeaders } from '@angular/common/http';
import { Injectable } from '@angular/core';

import 'rxjs/add/operator/map';
import { Headers } from '@angular/http';

@Injectable()
export class DataproviderProvider {

  constructor(public http: HttpClient) {
    console.log('Hello DataproviderProvider Provider');
  }

  // registering the user
  resgisterData(registerdata) {
    let headers = new Headers({'Content-Type': 'application/json'});
    this.http.post('http://localhost:3000/api/contact',registerdata,{headers: headers})
    .map(res => res.json());

  }
}

我收到类似

的错误消息

Argument of type '{ headers: Headers; }' is not assignable to parameter of type '{ headers?: HttpHeaders | { [header: string]: string | string[]; }; observe?: "body"; params?: Ht...'. Types of property 'headers' are incompatible. Type 'Headers' is not assignable to type 'HttpHeaders | { [header: string]: string | string[]; }'. Type 'Headers' is not assignable to type '{ [header: string]: string | string[]; }'. Index signature is missing in type 'Headers'.

在 visual studio 代码中，它在 {headers: headers}

处显示错误

Answer 1

似乎 HttpHeaders 的类型而不是 Headers。 这就是 Type 'Headers' is not assignable to type 'HttpHeaders' 的意思。

你应该这样

let header = new HttpHeaders();
header.append('Content-Type', 'application/json');