Angular 无法从组件向服务传递数据

我试图将参数传递给服务中定义的函数。参数总是

未定义的

login.component.ts

import { Component, OnInit } from '@angular/core';

import { AuthenticationService } from '../authentication.service';

@Component({
    selector: 'app-login',
    templateUrl: './login.component.html',
    styleUrls: ['./login.component.css'],
    providers: [AuthenticationService]
})
export class LoginComponent implements OnInit {

credentials: {
    username: '',
    password: ''
};

constructor(private _authenticationService: AuthenticationService) {}

ngOnInit() { }

login() {

    this._authenticationService.login(this.credentials).subscribe(
        response => console.log(response),
        error => console.log(error),
        () => console.log('Done.')
    );

}

import { Http } from '@angular/http';
import { Injectable } from '@angular/core';

@Injectable()
export class AuthenticationService {

constructor() { }

login(credentials) {

    console.log(credentials); // This is undefined

}

authentication.service.ts

import { Component, OnInit } from '@angular/core';

import { AuthenticationService } from '../authentication.service';

@Component({
    selector: 'app-login',
    templateUrl: './login.component.html',
    styleUrls: ['./login.component.css'],
    providers: [AuthenticationService]
})
export class LoginComponent implements OnInit {

credentials: {
    username: '',
    password: ''
};

constructor(private _authenticationService: AuthenticationService) {}

ngOnInit() { }

login() {

    this._authenticationService.login(this.credentials).subscribe(
        response => console.log(response),
        error => console.log(error),
        () => console.log('Done.')
    );

}

import { Http } from '@angular/http';
import { Injectable } from '@angular/core';

@Injectable()
export class AuthenticationService {

constructor() { }

login(credentials) {

    console.log(credentials); // This is undefined

}

---

我遗漏了什么？

您正在完美地传递数据，但问题是您使用类型

{username:''，password:''声明了变量
凭据
，您没有给它赋值，这就是它未定义的原因<代码>：

将类型分配给变量，

=

分配值。这就是你要找的：

credentials: any = {
    username: '',
    password: ''
};

---

啊。我用了

：

而不是

=

。谢谢Stefan。我应该删除这个问题吗？@KabirRoy这是真的，伙计，别担心。我看不出有什么理由删除它，但如果您愿意，您可以选择删除它。：-）