Angular 6:错误类型错误:无法读取未定义的属性“toLowerCase" [英] Angular 6: ERROR TypeError: Cannot read property 'toLowerCase' of undefined

问题描述

我正在创建关于用户的角度 6 的 CRUD 应用程序，当我尝试添加新用户时，出现以下错误:

这是我得到的错误:

core.js:12301 错误类型错误:无法读取未定义的属性toLowerCase"在 HttpXsrfInterceptor.push../node_modules/@angular/common/fesm5/http.js.HttpXsrfInterceptor.intercept (http.js:1718)在 HttpInterceptorHandler.push../node_modules/@angular/common/fesm5/http.js.HttpInterceptorHandler.handle (http.js:1134)在 HttpInterceptingHandler.push../node_modules/@angular/common/fesm5/http.js.HttpInterceptingHandler.handle (http.js:1769)在 MergeMapSubscriber.project (http.js:974)在 MergeMapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber._tryNext (mergeMap.js:61)在 MergeMapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber._next (mergeMap.js:51)在 MergeMapSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:54)在 Observable._subscribe (scalar.js:5)在 Observable.push../node_modules/rxjs/_esm5/internal/Observable.js.Observable._trySubscribe (Observable.js:43)在 Observable.push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe (Observable.js:29)

这里是添加用户组件html:

<div class="col-md-6"><h2 class="text-center">添加用户</h2><form [formGroup]="addForm" (ngSubmit)="onSubmit()"><div class="form-group"><label for="email">电子邮件地址:</label><input type="email" formControlName="email" placeholder="Email" name="email" class="form-control" id="email">
<div class="form-group"><label for="firstName">名字:</label><input formControlName="firstName" placeholder="First Name" name="firstName" class="form-control" id="firstName">

<div class="form-group"><label for="lastName">姓氏:</label><input formControlName="lastName" placeholder="Last name" name="lastName" class="form-control" id="lastName">

<button class="btn btn-success">更新</button></表单>

这里是 ts 文件:

import { Component, OnInit } from '@angular/core';从@angular/forms"导入 {FormBuilder、FormGroup、Validators}；从../service/user.service"导入{UserService}；从 'rxjs/operators' 导入 {first}；从 '@angular/router' 导入 {Router}；@成分({选择器:'app-add-user',templateUrl: './add-user.component.html',styleUrls: ['./add-user.component.scss']})导出类 AddUserComponent 实现 OnInit {构造函数(私有formBuilder:FormBuilder，私有路由器:路由器，私有userService:UserService){}添加表单:表单组；ngOnInit() {this.addForm = this.formBuilder.group({ID: []，电子邮件:[''，Validators.required]，名字:[''，Validators.required]，姓氏:[''，Validators.required]});}提交(){this.userService.createUser(this.addForm.value).订阅(数据=> {this.router.navigate(['list-user']);});}}

这里是用户服务:

import { Injectable } from '@angular/core';从'@angular/common/http' 导入 { HttpClient };从'../model/user.model'导入{用户}；@Injectable({提供在:'根'})导出类 UserService {构造函数(私有http:HttpClient){}baseUrl: 'http://locahost:4200/users';获取用户(){返回 this.http.get(this.baseUrl);}getUserById(id: number) {返回 this.http.get(this.baseUrl + '/' + id);}创建用户(用户:用户){返回 this.http.post(this.baseUrl, user);}更新用户(用户:用户){return this.http.put(this.baseUrl + '/' + user.id, user);}删除用户(ID:号码){返回 this.http.delete(this.baseUrl + '/' + id);}}

我尝试了不同的方法，但无法解决问题:)

我的应用程序做错了什么?任何帮助将不胜感激，谢谢

解决方案

更改

baseUrl: 'http://locahost:4200/users';

到

baseUrl='http://locahost:4200/users';

因为 baseUrl 的类型是字符串

I am creating CRUD app in angular six about users, when I am trying to add new user I am getting the following error:

Here is the error I am getting :

core.js:12301 ERROR TypeError: Cannot read property 'toLowerCase' of undefined
    at HttpXsrfInterceptor.push../node_modules/@angular/common/fesm5/http.js.HttpXsrfInterceptor.intercept (http.js:1718)
    at HttpInterceptorHandler.push../node_modules/@angular/common/fesm5/http.js.HttpInterceptorHandler.handle (http.js:1134)
    at HttpInterceptingHandler.push../node_modules/@angular/common/fesm5/http.js.HttpInterceptingHandler.handle (http.js:1769)
    at MergeMapSubscriber.project (http.js:974)
    at MergeMapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber._tryNext (mergeMap.js:61)
    at MergeMapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber._next (mergeMap.js:51)
    at MergeMapSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:54)
    at Observable._subscribe (scalar.js:5)
    at Observable.push../node_modules/rxjs/_esm5/internal/Observable.js.Observable._trySubscribe (Observable.js:43)
    at Observable.push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe (Observable.js:29)

Here is add user component html :

<div class="container add-user">
  <div class="col-md-6">
    <h2 class="text-center">Add User</h2>
    <form [formGroup]="addForm" (ngSubmit)="onSubmit()">
      <div class="form-group">
        <label for="email">Email address:</label>
        <input type="email" formControlName="email" placeholder="Email" name="email" class="form-control" id="email">
      </div>

      <div class="form-group">
        <label for="firstName">First Name:</label>
        <input formControlName="firstName" placeholder="First Name" name="firstName" class="form-control" id="firstName">
      </div>

      <div class="form-group">
        <label for="lastName">Last Name:</label>
        <input formControlName="lastName" placeholder="Last name" name="lastName" class="form-control" id="lastName">
      </div>

      <button class="btn btn-success">Update</button>
    </form>
  </div>
</div>

Here is ts file:

import { Component, OnInit } from '@angular/core';
import {FormBuilder, FormGroup, Validators} from '@angular/forms';
import {UserService} from '../service/user.service';
import {first} from 'rxjs/operators';
import {Router} from '@angular/router';

@Component({
  selector: 'app-add-user',
  templateUrl: './add-user.component.html',
  styleUrls: ['./add-user.component.scss']
})
export class AddUserComponent implements OnInit {

  constructor(private formBuilder: FormBuilder, private router: Router, private userService: UserService) { }

  addForm: FormGroup;

  ngOnInit() {

    this.addForm = this.formBuilder.group({
      id: [],
      email: ['', Validators.required],
      firstName: ['', Validators.required],
      lastName: ['', Validators.required]
    });

  }

  onSubmit() {
    this.userService.createUser(this.addForm.value)
      .subscribe( data => {
        this.router.navigate(['list-user']);
      });
  }

}

here is user service:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { User } from '../model/user.model';

@Injectable({
  providedIn: 'root'
})
export class UserService {

  constructor(private http: HttpClient) { }
  baseUrl: 'http://locahost:4200/users';

  getUsers() {
    return this.http.get<User[]>(this.baseUrl);
  }
  getUserById(id: number) {
    return this.http.get<User>(this.baseUrl + '/' + id);
  }
  createUser(user: User) {
    return this.http.post(this.baseUrl, user);
  }
  updateUser(user: User) {
    return this.http.put(this.baseUrl + '/' + user.id, user);
  }
  deleteUser(id: number) {
    return this.http.delete(this.baseUrl + '/' + id);
  }
}

I tried different ways but am not able to solve the issue :)

what am I doing wrong in my app? any help will be apreciated, thanks

解决方案

change the

baseUrl: 'http://locahost:4200/users';

to

baseUrl= 'http://locahost:4200/users';

since the type of baseUrl is string

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