Javascript 角度4:订阅可观察的
我正在从事一个项目,该项目要求加载和选择客户(不是用户,而是更像客户)。Javascript 角度4:订阅可观察的,javascript,angular,typescript,Javascript,Angular,Typescript,我正在从事一个项目,该项目要求加载和选择客户(不是用户,而是更像客户)。 不幸的是,我似乎无法订阅我在组件中加载的观测值。我已经尝试了在网上找到的所有可能的解决方案,但也许我对Angular的缺乏经验妨碍了我找到正确的解决方案 目前正在运行的功能: -在选择框中加载客户端 -为选择框中的选项提供客户端id值 -将客户端id发送到client.service并将所选客户端保存为可观察的 因此,我唯一的问题是组件没有注意到client.service中的可观察对象的变化 这是我的client.ser
不幸的是,我似乎无法订阅我在组件中加载的观测值。我已经尝试了在网上找到的所有可能的解决方案,但也许我对Angular的缺乏经验妨碍了我找到正确的解决方案 目前正在运行的功能:
-在选择框中加载客户端
-为选择框中的选项提供客户端id值
-将客户端id发送到client.service并将所选客户端保存为可观察的
因此,我唯一的问题是组件没有注意到client.service中的可观察对象的变化 这是我的client.service.ts:
import { Injectable } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { ApiService } from '../api.service';
import { Client } from './client';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/filter';
@Injectable()
export class ClientService {
clients$: Observable<Client[]>;
client: Client;
selectedClient$: Observable<Client[]>;
constructor(private api: ApiService) {
this.clients$ = this.getAll();
}
public getAll(): Observable<Client[]> {
return this.api.get<Client[]>('clients');
}
public setSelectedClient(clientId: number) {
this.clients$ = this.getAll();
if (clientId == null) {
// Do nothing
} else {
this.selectedClient$ = this.clients$.map(arr =>
{ return arr.find(client => client.id === clientId) });
}
}
public getSelectedClient() : Observable<Client> {
return this.selectedClient$;
}
}
从'@angular/core'导入{Injectable};
从“rxjs/Observable”导入{Observable};
从“../api.service”导入{ApiService};
从“/Client”导入{Client};
导入'rxjs/add/operator/map';
导入'rxjs/add/operator/filter';
@可注射()
导出类客户端服务{
客户美元:可观察;
客户:客户;
selectedClient$:可观察;
构造函数(私有api:ApiService){
this.clients$=this.getAll();
}
public getAll():可观察{
返回此.api.get('clients');
}
public SetSelected客户端(客户端ID:编号){
this.clients$=this.getAll();
if(clientId==null){
//无所事事
}否则{
this.selectedClient$=this.clients$.map(arr=>
{返回arr.find(client=>client.id==clientId)};
}
}
public getSelectedClient():可观察{
返回此。selectedClient$;
}
}
My component(我的组件),带有注释位以显示修复我的问题的一些尝试:
import { Component, OnInit } from '@angular/core';
import { Observable } from "rxjs/Observable";
import { ClientService } from "../client/client.service";
import { Client } from "../client/client";
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/filter';
@Component({
selector: 'app-left-menu',
templateUrl: './left-menu.component.html',
styleUrls: ['./left-menu.component.css']
})
export class LeftMenuComponent implements OnInit {
selectedClient$ : Observable<Client>;
client: Client = new Client();
clients$ : Observable<Client[]>;
constructor(private clientService: ClientService) {
}
ngOnInit() {
// this.clientService.getSelectedClient().subscribe(selectedClient$ => {
// this.selectedClient$ = Observable.of(selectedClient$);
// });
// //
// this.clientService.getAll().subscribe(clients$ => {
// this.clients$ = Observable.of(clients$);
// });
this.selectedClient$ = this.clientService.getSelectedClient();
this.clients$ = this.clientService.getAll();
}
public setSelectedClient(clientId: number) {
this.clientService.setSelectedClient(clientId);
}
}
从'@angular/core'导入{Component,OnInit};
从“rxjs/Observable”导入{Observable};
从“./client/client.service”导入{ClientService};
从“./Client/Client”导入{Client};
导入'rxjs/add/operator/map';
导入'rxjs/add/operator/filter';
@组成部分({
选择器:“应用程序左菜单”,
templateUrl:'/左菜单.component.html',
样式URL:['./左菜单.component.css']
})
导出类LeftMenuComponent实现OnInit{
selectedClient$:可观察;
客户机:客户机=新客户机();
客户美元:可观察;
构造函数(专用clientService:clientService){
}
恩戈尼尼特(){
//this.clientService.getSelectedClient().subscribe(selectedClient$=>{
//this.selectedClient$=可观察的(selectedClient$);
// });
// //
//this.clientService.getAll().subscribe(客户端$=>{
//此.clients$=可观察的(clients$);
// });
this.selectedClient$=this.clientService.getSelectedClient();
this.clients$=this.clientService.getAll();
}
public SetSelected客户端(客户端ID:编号){
this.clientService.setSelectedClient(clientId);
}
}
我用来显示和选择客户端的html部分:
<select #selectClient [ngModel]="selectedClient$ | async"
(ngModelChange)="setSelectedClient(selectClient.value)">
<option *ngFor="let client of clients$ | async" [value]="client.id">
{{ client.firstName }}
{{ client.preposition }}
{{ client.lastName }}
</option>
</select>
<!-- Displaying selected client -->
<h2 *ngIf="selectedClient$">{{(selectedClient$ | async)?.firstName}}
</h2>
{{client.firstName}
{{client.preposition}}
{{client.lastName}
{{(selectedClient$| async)?.firstName}
如果有人能帮我解决这个问题,我将不胜感激,谢谢 您的问题源于您将
客户端$
和selectedClient$
可观察属性分配给LeftMenuComponent
的方式
ClientService
上的setSelectedClient()
方法将更改服务的属性。但是,您的LeftMenuComponent
的ngOnInit()
只分配一次属性,并且setSelectedClient()
中的更改不会反映在LeftMenuComponent上
若要实现这一点,不需要将特性重新指定给组件。您可以简单地将服务的属性直接绑定到模板中,如下所示:
<select #selectClient [ngModel]="clientService.selectedClient$ | async"
(ngModelChange)="setSelectedClient(selectClient.value)">
<option *ngFor="let client of clientService.clients$ | async" [value]="client.id">
{{ client.firstName }}
{{ client.preposition }}
{{ client.lastName }}
</option>
</select>
export class LeftMenuComponent implements OnInit {
client: Client = new Client();
get selectedClient$(): Observable<Client> {
return this.clientService.selectedClient$;
}
get clients$(): Observable<Client> {
return this.clientService.client$;
}
constructor(private clientService: ClientService) {
}
ngOnInit() {
// init things, but no assignment needed now
}
{{client.firstName}
{{client.preposition}}
{{client.lastName}
另一种可能更简洁的方法是在组件上使用getter属性,而不是赋值,如下所示:
<select #selectClient [ngModel]="clientService.selectedClient$ | async"
(ngModelChange)="setSelectedClient(selectClient.value)">
<option *ngFor="let client of clientService.clients$ | async" [value]="client.id">
{{ client.firstName }}
{{ client.preposition }}
{{ client.lastName }}
</option>
</select>
export class LeftMenuComponent implements OnInit {
client: Client = new Client();
get selectedClient$(): Observable<Client> {
return this.clientService.selectedClient$;
}
get clients$(): Observable<Client> {
return this.clientService.client$;
}
constructor(private clientService: ClientService) {
}
ngOnInit() {
// init things, but no assignment needed now
}
导出类LeftMenuComponent实现OnInit{
客户机:客户机=新客户机();
get selectedClient$():可观察{
返回此.clientService.selectedClient$;
}
获取客户端$():可观察{
返回此.clientService.client$;
}
构造函数(专用clientService:clientService){
}
恩戈尼尼特(){
//开始工作,但现在不需要分配任务
}
使用[ngValue]
而不是[value]
将客户端对象本身绑定到[ngModel]
指令,我还使用Subject
轻松通知新选择的客户端的其他订户:
client.service.ts:
import { Injectable } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { Subject } from 'rxjs/Subject';
import { Client } from './client';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/filter';
@Injectable()
export class ClientService {
clients$: Observable<Client[]>;
client: Client;
selectedClient$: Subject<Client> = new Subject<Client>();
//...
public setSelectedClient(client: Client) {
if (client)
this.selectedClient$.next(client);
}
//...
}
从'@angular/core'导入{Injectable};
从“rxjs/Observable”导入{Observable};
从'rxjs/Subject'导入{Subject};
从“/Client”导入{Client};
导入'rxjs/add/operator/map';
导入'rxjs/add/operator/filter';
@可注射()
导出类客户端服务{
客户美元:可观察;
客户:客户;
selectedClient$:Subject=新主题();
//...
公共设置选定客户端(客户端:客户端){
如果(客户)
this.selectedClient$.next(客户端);
}
//...
}
组件1.ts:
import { Component } from '@angular/core';
import { Observable } from 'rxjs/Observable';
import { ClientService } from './client.service';
import { Client } from './client'
@Component({
selector: 'my-app',
templateUrl: './app.component.html',
styleUrls: [ './app.component.css' ]
})
export class AppComponent {
selectedClient : Client;
client: Client = new Client();
clients$ : Observable<Client[]>;
constructor(private clientService: ClientService) {
}
ngOnInit() {
//...
this.clients$ = this.clientService.getAll();
this.clientService.selectedClient$.subscribe(console.log)
}
setSelectedClient(client : Client){
this.selectedClient = client;
this.clientService.setSelectedClient(client)
}
}
从'@angular/core'导入{Component};
从“rxjs/Observable”导入{Observable};
从“/client.service”导入{ClientService};
从“./Client”导入{Client}
@组成部分({
选择器:“我的应用程序”,
templateUrl:“./app.component.html”,
样式URL:['./app.component.css']
})
导出类AppComponent{
selectedClient:Client;
客户机:客户机=新客户机();
客户美元:可观察;