为什么我的 select 不显示我提供给它的数据? Angular 10

Why my select doesn't display the data that I'm giving to it? Angular 10

我在 angular 项目的 html 模板中遇到 select 问题。 问题是我有所有国家的 JSON。

语言界面

export interface Country{
    name:string
    code:string
  }

countries.json

[
    {"name": "Afghanistan", "code": "AF"},
    {"name": "Åland Islands", "code": "AX"},
    {"name": "Albania", "code": "AL"},
    {"name": "Algeria", "code": "DZ"},
    {"name": "American Samoa", "code": "AS"},
    {"name": "AndorrA", "code": "AD"},
    {"name": "Angola", "code": "AO"},
    {"name": "Anguilla", "code": "AI"},
    {"name": "Antarctica", "code": "AQ"},
    {"name": "Antigua and Barbuda", "code": "AG"},
    {"name": "Argentina", "code": "AR"},
    {"name": "Armenia", "code": "AM"},
    {"name": "Aruba", "code": "AW"},
    {"name": "Australia", "code": "AU"},
    {"name": "Austria", "code": "AT"},
    {"name": "Azerbaijan", "code": "AZ"},
    {"name": "Bahamas", "code": "BS"},
    {"name": "Bahrain", "code": "BH"},
    {"name": "Bangladesh", "code": "BD"},
    {"name": "Barbados", "code": "BB"},
    {"name": "Belarus", "code": "BY"},
    {"name": "Belgium", "code": "BE"},
    {"name": "Belize", "code": "BZ"},
    {"name": "Benin", "code": "BJ"},
    {"name": "Bermuda", "code": "BM"},
    {"name": "Bhutan", "code": "BT"},
    {"name": "Bolivia", "code": "BO"},
    {"name": "Bosnia and Herzegovina", "code": "BA"},
    {"name": "Botswana", "code": "BW"},
    {"name": "Bouvet Island", "code": "BV"},
    {"name": "Brazil", "code": "BR"},
    {"name": "British Indian Ocean Territory", "code": "IO"},
    {"name": "Brunei Darussalam", "code": "BN"},
    {"name": "Bulgaria", "code": "BG"},
    {"name": "Burkina Faso", "code": "BF"},
    {"name": "Burundi", "code": "BI"},
    {"name": "Cambodia", "code": "KH"},
    {"name": "Cameroon", "code": "CM"},
    {"name": "Canada", "code": "CA"},
    {"name": "Cape Verde", "code": "CV"},
    {"name": "Cayman Islands", "code": "KY"},
    {"name": "Central African Republic", "code": "CF"},
    {"name": "Chad", "code": "TD"},
    {"name": "Chile", "code": "CL"},
    {"name": "China", "code": "CN"},
    {"name": "Christmas Island", "code": "CX"},
    {"name": "Cocos (Keeling) Islands", "code": "CC"},
    {"name": "Colombia", "code": "CO"},
    {"name": "Comoros", "code": "KM"},
    {"name": "Congo", "code": "CG"},
    {"name": "Congo, The Democratic Republic of the", "code": "CD"},
    {"name": "Cook Islands", "code": "CK"},
    {"name": "Costa Rica", "code": "CR"},
    {"name": "Cote D'Ivoire", "code": "CI"},
    {"name": "Croatia", "code": "HR"},
    {"name": "Cuba", "code": "CU"},
    {"name": "Cyprus", "code": "CY"},
    {"name": "Czech Republic", "code": "CZ"},
    {"name": "Denmark", "code": "DK"},
    {"name": "Djibouti", "code": "DJ"},
    {"name": "Dominica", "code": "DM"},
    {"name": "Dominican Republic", "code": "DO"},
    {"name": "Ecuador", "code": "EC"},
    {"name": "Egypt", "code": "EG"},
    {"name": "El Salvador", "code": "SV"},
    {"name": "Equatorial Guinea", "code": "GQ"},
    {"name": "Eritrea", "code": "ER"},
    {"name": "Estonia", "code": "EE"},
    {"name": "Ethiopia", "code": "ET"},
    {"name": "Falkland Islands (Malvinas)", "code": "FK"},
    {"name": "Faroe Islands", "code": "FO"},
    {"name": "Fiji", "code": "FJ"},
    {"name": "Finland", "code": "FI"},
    {"name": "France", "code": "FR"},
    {"name": "French Guiana", "code": "GF"},
    {"name": "French Polynesia", "code": "PF"},
    {"name": "French Southern Territories", "code": "TF"},
    {"name": "Gabon", "code": "GA"},
    {"name": "Gambia", "code": "GM"},
    {"name": "Georgia", "code": "GE"},
    {"name": "Germany", "code": "DE"},
    {"name": "Ghana", "code": "GH"},
    {"name": "Gibraltar", "code": "GI"},
    {"name": "Greece", "code": "GR"},
    {"name": "Greenland", "code": "GL"},
    {"name": "Grenada", "code": "GD"},
    {"name": "Guadeloupe", "code": "GP"},
    {"name": "Guam", "code": "GU"},
    {"name": "Guatemala", "code": "GT"},
    {"name": "Guernsey", "code": "GG"},
    {"name": "Guinea", "code": "GN"},
    {"name": "Guinea-Bissau", "code": "GW"},
    {"name": "Guyana", "code": "GY"},
    {"name": "Haiti", "code": "HT"},
    {"name": "Heard Island and Mcdonald Islands", "code": "HM"},
    {"name": "Holy See (Vatican City State)", "code": "VA"},
    {"name": "Honduras", "code": "HN"},
    {"name": "Hong Kong", "code": "HK"},
    {"name": "Hungary", "code": "HU"},
    {"name": "Iceland", "code": "IS"},
    {"name": "India", "code": "IN"},
    {"name": "Indonesia", "code": "ID"},
    {"name": "Iran, Islamic Republic Of", "code": "IR"},
    {"name": "Iraq", "code": "IQ"},
    {"name": "Ireland", "code": "IE"},
    {"name": "Isle of Man", "code": "IM"},
    {"name": "Israel", "code": "IL"},
    {"name": "Italy", "code": "IT"},
    {"name": "Jamaica", "code": "JM"},
    {"name": "Japan", "code": "JP"},
    {"name": "Jersey", "code": "JE"},
    {"name": "Jordan", "code": "JO"},
    {"name": "Kazakhstan", "code": "KZ"},
    {"name": "Kenya", "code": "KE"},
    {"name": "Kiribati", "code": "KI"},
    {"name": "Korea, Democratic People's Republic of", "code": "KP"},
    {"name": "Korea, Republic of", "code": "KR"},
    {"name": "Kuwait", "code": "KW"},
    {"name": "Kyrgyzstan", "code": "KG"},
    {"name": "Lao People's Democratic Republic", "code": "LA"},
    {"name": "Latvia", "code": "LV"},
    {"name": "Lebanon", "code": "LB"},
    {"name": "Lesotho", "code": "LS"},
    {"name": "Liberia", "code": "LR"},
    {"name": "Libyan Arab Jamahiriya", "code": "LY"},
    {"name": "Liechtenstein", "code": "LI"},
    {"name": "Lithuania", "code": "LT"},
    {"name": "Luxembourg", "code": "LU"},
    {"name": "Macao", "code": "MO"},
    {"name": "Macedonia, The Former Yugoslav Republic of", "code": "MK"},
    {"name": "Madagascar", "code": "MG"},
    {"name": "Malawi", "code": "MW"},
    {"name": "Malaysia", "code": "MY"},
    {"name": "Maldives", "code": "MV"},
    {"name": "Mali", "code": "ML"},
    {"name": "Malta", "code": "MT"},
    {"name": "Marshall Islands", "code": "MH"},
    {"name": "Martinique", "code": "MQ"},
    {"name": "Mauritania", "code": "MR"},
    {"name": "Mauritius", "code": "MU"},
    {"name": "Mayotte", "code": "YT"},
    {"name": "Mexico", "code": "MX"},
    {"name": "Micronesia, Federated States of", "code": "FM"},
    {"name": "Moldova, Republic of", "code": "MD"},
    {"name": "Monaco", "code": "MC"},
    {"name": "Mongolia", "code": "MN"},
    {"name": "Montserrat", "code": "MS"},
    {"name": "Morocco", "code": "MA"},
    {"name": "Mozambique", "code": "MZ"},
    {"name": "Myanmar", "code": "MM"},
    {"name": "Namibia", "code": "NA"},
    {"name": "Nauru", "code": "NR"},
    {"name": "Nepal", "code": "NP"},
    {"name": "Netherlands", "code": "NL"},
    {"name": "Netherlands Antilles", "code": "AN"},
    {"name": "New Caledonia", "code": "NC"},
    {"name": "New Zealand", "code": "NZ"},
    {"name": "Nicaragua", "code": "NI"},
    {"name": "Niger", "code": "NE"},
    {"name": "Nigeria", "code": "NG"},
    {"name": "Niue", "code": "NU"},
    {"name": "Norfolk Island", "code": "NF"},
    {"name": "Northern Mariana Islands", "code": "MP"},
    {"name": "Norway", "code": "NO"},
    {"name": "Oman", "code": "OM"},
    {"name": "Pakistan", "code": "PK"},
    {"name": "Palau", "code": "PW"},
    {"name": "Palestinian Territory, Occupied", "code": "PS"},
    {"name": "Panama", "code": "PA"},
    {"name": "Papua New Guinea", "code": "PG"},
    {"name": "Paraguay", "code": "PY"},
    {"name": "Peru", "code": "PE"},
    {"name": "Philippines", "code": "PH"},
    {"name": "Pitcairn", "code": "PN"},
    {"name": "Poland", "code": "PL"},
    {"name": "Portugal", "code": "PT"},
    {"name": "Puerto Rico", "code": "PR"},
    {"name": "Qatar", "code": "QA"},
    {"name": "Reunion", "code": "RE"},
    {"name": "Romania", "code": "RO"},
    {"name": "Russian Federation", "code": "RU"},
    {"name": "RWANDA", "code": "RW"},
    {"name": "Saint Helena", "code": "SH"},
    {"name": "Saint Kitts and Nevis", "code": "KN"},
    {"name": "Saint Lucia", "code": "LC"},
    {"name": "Saint Pierre and Miquelon", "code": "PM"},
    {"name": "Saint Vincent and the Grenadines", "code": "VC"},
    {"name": "Samoa", "code": "WS"},
    {"name": "San Marino", "code": "SM"},
    {"name": "Sao Tome and Principe", "code": "ST"},
    {"name": "Saudi Arabia", "code": "SA"},
    {"name": "Senegal", "code": "SN"},
    {"name": "Serbia and Montenegro", "code": "CS"},
    {"name": "Seychelles", "code": "SC"},
    {"name": "Sierra Leone", "code": "SL"},
    {"name": "Singapore", "code": "SG"},
    {"name": "Slovakia", "code": "SK"},
    {"name": "Slovenia", "code": "SI"},
    {"name": "Solomon Islands", "code": "SB"},
    {"name": "Somalia", "code": "SO"},
    {"name": "South Africa", "code": "ZA"},
    {"name": "South Georgia and the South Sandwich Islands", "code": "GS"},
    {"name": "Spain", "code": "ES"},
    {"name": "Sri Lanka", "code": "LK"},
    {"name": "Sudan", "code": "SD"},
    {"name": "Suriname", "code": "SR"},
    {"name": "Svalbard and Jan Mayen", "code": "SJ"},
    {"name": "Swaziland", "code": "SZ"},
    {"name": "Sweden", "code": "SE"},
    {"name": "Switzerland", "code": "CH"},
    {"name": "Syrian Arab Republic", "code": "SY"},
    {"name": "Taiwan, Province of China", "code": "TW"},
    {"name": "Tajikistan", "code": "TJ"},
    {"name": "Tanzania, United Republic of", "code": "TZ"},
    {"name": "Thailand", "code": "TH"},
    {"name": "Timor-Leste", "code": "TL"},
    {"name": "Togo", "code": "TG"},
    {"name": "Tokelau", "code": "TK"},
    {"name": "Tonga", "code": "TO"},
    {"name": "Trinidad and Tobago", "code": "TT"},
    {"name": "Tunisia", "code": "TN"},
    {"name": "Turkey", "code": "TR"},
    {"name": "Turkmenistan", "code": "TM"},
    {"name": "Turks and Caicos Islands", "code": "TC"},
    {"name": "Tuvalu", "code": "TV"},
    {"name": "Uganda", "code": "UG"},
    {"name": "Ukraine", "code": "UA"},
    {"name": "United Arab Emirates", "code": "AE"},
    {"name": "United Kingdom", "code": "GB"},
    {"name": "United States", "code": "US"},
    {"name": "United States Minor Outlying Islands", "code": "UM"},
    {"name": "Uruguay", "code": "UY"},
    {"name": "Uzbekistan", "code": "UZ"},
    {"name": "Vanuatu", "code": "VU"},
    {"name": "Venezuela", "code": "VE"},
    {"name": "Viet Nam", "code": "VN"},
    {"name": "Virgin Islands, British", "code": "VG"},
    {"name": "Virgin Islands, U.S.", "code": "VI"},
    {"name": "Wallis and Futuna", "code": "WF"},
    {"name": "Western Sahara", "code": "EH"},
    {"name": "Yemen", "code": "YE"},
    {"name": "Zambia", "code": "ZM"},
    {"name": "Zimbabwe", "code": "ZW"}
  ]

这就是我得到它们的方式。

service.ts

  createdCountry: Country = {
    name:'',
    code:''
  }
  country: Country[];

  getCountries(){
    return this.http.get<Country[]>('../assets/countries/countries.json');
  }

这是我获取数据并将其发送到模板的组件。

component.ts

  getCountries(){
    this.clientService.getCountries().subscribe(countries => {
      this.clientService.country = countries;
      console.log(countries);
    })
  }

这是数据

现在,在我的模板中我得到了这个(我必须 select 一个国家并将其分配给客户,这就是为什么在 ngModel 中我有 clienteService.createdClient.pais)

        <div class="col-md-8">
            <div class="cardForm">
                <div class="card">
                    <div class="card-body">
                        <h2>Ingresar Cliente al Sistema</h2>
                        <form #clienteForm="ngForm" (ngSubmit)="addClient(clienteForm)"> 
                            <div class="form-group">
                                <input type="text" class="form-control"  name="nombreCliente" placeholder="Ingrese nombre del cliente" required [(ngModel)]="clientService.createdClient.nombreCliente" #nombreCliente="ngModel">
                            </div>
                            <div class="form-group">
                                <select name="pais" [(ngModel)]="clientService.createdClient.pais" class="form-control selectpicker" data-live-search="true" #pais="ngModel">
                                    <option *ngFor="let country of clientService.country" [ngValue]="country">{{ country.name }}</option>
                                </select>
                            </div>
                            <button class="btn btn-secondary"> 
                                Save
                            </button>
                        </form>
                    </div>
                </div>
            </div>
        </div>

但是 select 是空的。

我该如何解决这个问题?

提前致谢。

编辑

客户端.service.ts

import { Injectable } from '@angular/core';
import { Cliente } from '../models/clientes';
import { Country } from '../models/languages';
import { HttpClient } from '@angular/common/http';
import { Router } from '@angular/router';


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

  URL_CREATE = 'http://localhost:3000/api/clients/addClient';
  URL_GETALLCLIENTS = 'http://localhost:3000/api/clients/getClients';

  createdClient : Cliente ={
    nombreCliente: '',
    pais: ''
  };
  createdCountry: Country = {
    name:'',
    code:''
  }
  country: Country[];
  client : Cliente[];
  constructor(private http : HttpClient,private router: Router ) { }

  createClient(client: Cliente){
    return this.http.post(this.URL_CREATE,client,{observe :'response'})
  }

  getClients(){
    return this.http.get<Cliente[]>(this.URL_GETALLCLIENTS);
  }

  getCountries(){
    return this.http.get<Country[]>('../assets/countries/countries.json');
  }
}

客户.component.ts

import { Component, OnInit,ViewChild } from '@angular/core';
import { ClienteService } from '../../services/cliente.service';
import { NgForm} from '@angular/forms';
import { Cliente } from 'src/app/models/clientes';
import { Router } from '@angular/router';
import { Country } from 'src/app/models/languages';



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


  constructor(
    public clientService : ClienteService,
    private router : Router

  ) {

   }

  ngOnInit(): void {

    $('.selectpicker').selectpicker();
    this.getClients();
    this.getCountries()
  }





  addClient(form: NgForm){
    this.clientService.createClient(form.value).subscribe(
      res => {
        this.getClients();
        form.resetForm();
        this.router.navigate(['/addClient']);
        console.log(res);
        console.log(form);
      },
      err => {
        console.log(err);
      }
    )

  }

  getClients(){
    this.clientService.getClients().subscribe(
      res => {
        if(res !== undefined){
          this.clientService.client = res;
        }
      },
      err => console.log(err)
    )
  }

  getCountries(){
    this.clientService.getCountries().subscribe(countries => {
      this.clientService.country = countries;
      console.log(countries);
    })
  }
}

首先:

不要滥用 Typescript 中的默认访问修饰符是 public 这一事实。您不应该直接从组件向服务分配值 属性。作为一种好的做法,您可以将服务的所有属性更改为私有。当您需要从外部访问它们时,请为此创建一个方法。另外,避免在 Angular 中使用 jQuery。这个框架有他自己的工具影响DOM。另一种Directives

关于问题: 在组件中创建“国家”属性,并通过 getCountries 方法从中赋值。

getCountries(){
  this.countriesList = this.clientService.getCountries()
}

<option *ngFor="let country of (countriesList | async)" [ngValue]="country">{{ country.name}}</option>