未捕获的SyntaxError：在Response.Body.json的JSON.parse（< anonymous>）位置0的JSON中出现意外的标记U [英] Uncaught SyntaxError: Unexpected token U in JSON at position 0 at JSON.parse (<anonymous>) at Response.Body.json
问题描述
我正在开发一个angular2项目。我遇到了这些错误。当我尝试将JSON对象发送到后端时发生错误。这可能是由于JSON对象的解析。我是angualar的新手，所以请帮忙
I am working on an angular2 project. I am stuck with these errors. The error occured when I tried to send the JSON objects to the backend. It may be due the parsing of JSON objects. I am new to angualar, so please do help
Signup.service.ts
Signup.service.ts
import {Injectable} from '@angular/core';
import {Http, Headers} from '@angular/http';
import 'rxjs/add/operator/map' ;
@Injectable()
export class SignupService{
constructor (private http: Http){}
insertform(newreg: any ){
console.log();
var headers = new Headers ();
headers.append('Content-Type','application/json');
return this.http.post('http://localhost:3000/api/users', JSON.stringify(newreg),{headers: headers})
.map(res=> res.json());
}
}
signup.component.ts
signup.component.ts
import { Component, AfterViewInit } from '@angular/core';
import {SignupService} from '../../services/signup.service';
import {Signup} from '../../../signup';
declare var $: any;
@Component({
moduleId: module.id,
selector: 'signup',
templateUrl: 'signup.component.html',
providers: [SignupService]
})
export class SignupComponent {
datas: Signup[];
data: any;
first_name: string;
last_name: string;
address: string;
email: string;
pwd:string;
pwdcnf:string;
phone:number;
constructor(private signupService: SignupService){ };
ngAfterViewInit() {
$('#textarea1').trigger('autoresize');
};
regformSubmit(event: any){
event.preventDefault();
var newreg = {
first_name: this.first_name,
last_name: this.last_name,
email: this.email,
address: this.address,
phone: this.phone,
pwd:this.pwd,
pwdcnf:this.pwdcnf
};
this.signupService.insertform(newreg)
.subscribe (data => {
this.datas.push(data);
this.first_name='';
this.last_name ='';
this.email='';
this.address='';
this.phone=0;
this.pwd='';
this.pwdcnf='';
});
}
}
signup.component.html
signup.component.html
<div class="container light-blue lighten-5">
<form class="col s12" (ngSubmit)="regformSubmit($event)">
<div class="row">
<div class="input-field col s6">
<input id="first_name" type="text" class="validate" [(ngModel)]="first_name" name="first_name" required>
<label for="first_name">First Name</label>
</div>
<div class="input-field col s6">
<input id="last_name" type="text" class="validate" [(ngModel)]="last_name" name="last_name" required>
<label for="last_name">Last Name</label>
</div>
</div>
<div class="row">
<div class="input-field col s12">
<textarea id="textarea1" class="materialize-textarea" [(ngModel)]="address" name="address" required></textarea>
<label for="disabled">Address</label>
</div>
</div>
<div class="row ">
<div class="input-field col s5">
<input id="password" type="password" class="validate" [(ngModel)]="pwd" name="pwd" required>
<label for="password">Password</label>
</div>
<div class="input-field col s5 offset-s2">
<input id="password1" type="password" class="validate" [(ngModel)]="pwdcnf" name="pwdcnf" required>
<label for="password1">Confirm password</label>
</div>
</div>
<div class="row">
<div class="input-field col s5">
<input id="email" type="email" class="validate" [(ngModel)]="email" name="email" required>
<label for="email">Email</label>
</div>
<div class="input-field col s5 offset-s2">
<input id="password2" type="number" class="validate" [(ngModel)]="phone" name="number" required>
<label for="password2">Phone</label>
</div>
</div>
<div class="row">
<div class="input-field col s4 offset-s5">
<button class="btn waves-effect waves-light" type="submit" name="action">Submit
<i class="material-icons right">send</i>
</button>
</div>
</div>
</form>
</div>
<style>
.ng-invalid {
border-bottom-color: red;
}
</style>
完整的错误消息是
EXCEPTION: Unexpected token U in JSON at position 0
ORIGINAL STACKTRACE:
yntaxError: Unexpected token U in JSON at position 0
at JSON.parse (<anonymous>)
at Response.Body.json (http.umd.js:777)
at MapSubscriber.eval [as project] (signup.service.ts:13)
at MapSubscriber._next (map.ts:75)
at MapSubscriber.Subscriber.next (Subscriber.ts:95)
at XMLHttpRequest.onLoad (http.umd.js:1180)
at ZoneDelegate.invokeTask (zone.js:275)
at Object.onInvokeTask (core.umd.js:3971)
at ZoneDelegate.invokeTask (zone.js:274)
at Zone.runTask (zone.js:151)
at XMLHttpRequest.ZoneTask.invoke (zone.js:345)
Uncaught SyntaxError: Unexpected token U in JSON at position 0
at JSON.parse (<anonymous>)
at Response.Body.json (http.umd.js:777)
at MapSubscriber.eval [as project] (signup.service.ts:13)
at MapSubscriber._next (map.ts:75)
at MapSubscriber.Subscriber.next (Subscriber.ts:95)
at XMLHttpRequest.onLoad (http.umd.js:1180)
at ZoneDelegate.invokeTask (zone.js:275)
at Object.onInvokeTask (core.umd.js:3971)
at ZoneDelegate.invokeTask (zone.js:274)
at Zone.runTask (zone.js:151)
at XMLHttpRequest.ZoneTask.invoke (zone.js:345)
推荐答案
我经常在服务器返回错误时看到这个（例如500服务器错误）。问题是服务器返回纯文本，有时甚至是HTML，然后客户端应用程序试图从中解析JSON，从而抛出错误。我建议打开chrome dev工具，导航到网络选项卡，刷新页面，然后查找有问题的请求，看看实际从服务器返回的内容。
I normally see this when the server returns an error (e.g. a 500 server error). The problem is that the server is returning plain text or sometimes even HTML and then the client app is trying to parse JSON from it thus throwing the error. I would recommend opening the chrome dev tools, navigating to the network tab, refreshing the page, and then look for the request in question and see what is actually getting returned from the server.
看起来应该是这样的。我的猜测是右边的文字不是JSON。
It should look something like this. My guess is that the text on the right will not be JSON.
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