Javascript 角6服务注入异常
我两天前开始使用angular,我正在尝试创建一个服务,该服务将在我的spring boot rest端点上执行get请求,我希望在angular应用程序中显示结果 这是我到现在为止一直在尝试的 我的服务:Javascript 角6服务注入异常,javascript,angular,angular-services,Javascript,Angular,Angular Services,我两天前开始使用angular,我正在尝试创建一个服务,该服务将在我的spring boot rest端点上执行get请求,我希望在angular应用程序中显示结果 这是我到现在为止一直在尝试的 我的服务: import { Injectable } from '@angular/core'; import { HttpClient } from '@angular/common/http'; import { ITweet } from './itweet'; import { Observa
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { ITweet } from './itweet';
import { Observable } from 'rxjs';
@Injectable({
providedIn: 'root'
})
export class ReactiveTwitterService {
constructor(private http_client: HttpClient, private tweetTag: string) { }
spring_webflux_service_url = 'http://localhost:8081/search';
myTweets: Observable<ITweet[]>;
setTweetTag(tag) {
this.tweetTag = tag;
}
seearchTweets() {
this.myTweets = this.http_client.get<ITweet[]>(this.spring_webflux_service_url + '/' + this.tweetTag);
}
getTweets() {
return this.myTweets;
}
}
我的应用程序模块看起来像这样
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import {HttpClientModule} from '@angular/common/http';
import { FormsModule } from '@angular/forms';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { SerachBarComponent } from './serach-bar/serach-bar.component';
import { SearchReasultComponent } from './search-reasult/search-reasult.component';
import { HeaderComponent } from './header/header.component';
import { ResultItemComponent } from './result-item/result-item.component';
@NgModule({
declarations: [
AppComponent,
HeaderComponent,
SerachBarComponent,
SearchReasultComponent,
ResultItemComponent
],
imports: [
BrowserModule,
AppRoutingModule,
HttpClientModule,
FormsModule
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }
我在谷歌上搜索到,由于服务实现中的providedIn指令,没有必要在提供者中设置我的服务
我使用此服务的组件
export interface ITweet {
id: {
text: string,
name: string
};
tag: string;
}
import { Component, HostListener } from '@angular/core';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
innerWidth: number;
styleClass = {
wide_screen: 'w3-light-grey',
break_point: 'w3-dark-grey'
};
@HostListener('window:resize', ['$event'])
onResize(event) {
this.innerWidth = window.innerWidth;
}
getStyle() {
return (innerWidth > 769) ? this.styleClass.wide_screen : this.styleClass.break_point;
}
}
和
import { Component, OnInit, HostListener } from '@angular/core';
import { ReactiveTwitterService } from '../reactive-twitter.service';
@Component({
selector: 'app-serach-bar',
templateUrl: './serach-bar.component.html',
styleUrls: ['./serach-bar.component.css']
})
export class SerachBarComponent implements OnInit {
innerWidth: number;
constructor(private twiterService: ReactiveTwitterService) { }
placeholder = 'search';
styleClass = {
wide_screen: 'w3-input w3-light-grey',
break_point: 'w3-input w3-white'
};
doSearch(tag) {
this.twiterService.setTweetTag(tag);
this.twiterService.seearchTweets();
}
ngOnInit() {
}
@HostListener('window:resize', ['$event'])
onResize(event) {
this.innerWidth = window.innerWidth;
}
getStyle() {
return (innerWidth > 769) ? this.styleClass.wide_screen : this.styleClass.break_point;
}
}
import { Component, OnInit, HostListener } from '@angular/core';
import { ReactiveTwitterService } from '../reactive-twitter.service';
import { ITweet } from '../itweet';
@Component({
selector: 'app-search-reasult',
templateUrl: './search-reasult.component.html',
styleUrls: ['./search-reasult.component.css']
})
export class SearchReasultComponent implements OnInit {
search_result: ITweet[];
innerWidth: number;
constructor(private _twitterService: ReactiveTwitterService) { }
styleClass = {
wide_screen: 'w3-ul w3-hoverable',
break_point: 'w3-green w3-container'
};
ngOnInit() {
this._twitterService.getTweets().subscribe(tweet => this.search_result = tweet);
}
is_search_result_empty() {
return this.search_result === [];
}
set_search_result_empty() {
this.search_result = [];
}
@HostListener('window:resize', ['$event'])
onResize(event) {
this.innerWidth = window.innerWidth;
}
get_list_style() {
return (innerWidth > 769) ? this.styleClass.wide_screen : this.styleClass.break_point;
}
}
和
import { Component, OnInit, HostListener } from '@angular/core';
import { ReactiveTwitterService } from '../reactive-twitter.service';
@Component({
selector: 'app-serach-bar',
templateUrl: './serach-bar.component.html',
styleUrls: ['./serach-bar.component.css']
})
export class SerachBarComponent implements OnInit {
innerWidth: number;
constructor(private twiterService: ReactiveTwitterService) { }
placeholder = 'search';
styleClass = {
wide_screen: 'w3-input w3-light-grey',
break_point: 'w3-input w3-white'
};
doSearch(tag) {
this.twiterService.setTweetTag(tag);
this.twiterService.seearchTweets();
}
ngOnInit() {
}
@HostListener('window:resize', ['$event'])
onResize(event) {
this.innerWidth = window.innerWidth;
}
getStyle() {
return (innerWidth > 769) ? this.styleClass.wide_screen : this.styleClass.break_point;
}
}
import { Component, OnInit, HostListener } from '@angular/core';
import { ReactiveTwitterService } from '../reactive-twitter.service';
import { ITweet } from '../itweet';
@Component({
selector: 'app-search-reasult',
templateUrl: './search-reasult.component.html',
styleUrls: ['./search-reasult.component.css']
})
export class SearchReasultComponent implements OnInit {
search_result: ITweet[];
innerWidth: number;
constructor(private _twitterService: ReactiveTwitterService) { }
styleClass = {
wide_screen: 'w3-ul w3-hoverable',
break_point: 'w3-green w3-container'
};
ngOnInit() {
this._twitterService.getTweets().subscribe(tweet => this.search_result = tweet);
}
is_search_result_empty() {
return this.search_result === [];
}
set_search_result_empty() {
this.search_result = [];
}
@HostListener('window:resize', ['$event'])
onResize(event) {
this.innerWidth = window.innerWidth;
}
get_list_style() {
return (innerWidth > 769) ? this.styleClass.wide_screen : this.styleClass.break_point;
}
}
我的模板是
export interface ITweet {
id: {
text: string,
name: string
};
tag: string;
}
import { Component, HostListener } from '@angular/core';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
innerWidth: number;
styleClass = {
wide_screen: 'w3-light-grey',
break_point: 'w3-dark-grey'
};
@HostListener('window:resize', ['$event'])
onResize(event) {
this.innerWidth = window.innerWidth;
}
getStyle() {
return (innerWidth > 769) ? this.styleClass.wide_screen : this.styleClass.break_point;
}
}
AppComponent
<div class="{{getStyle()}}" style="width: 100%;height: 100%;">
<app-header></app-header>
<app-serach-bar></app-serach-bar>
<app-search-reasult></app-search-reasult>
</div>
<div class="w3-container" *ngIf="!is_search_result_empty">
<ul class="{{get_list_style()}}">
<app-result-item *ngFor="let current_item of search_result; trackBy:current_item.id" [item]="current_item"></app-result-item>
</ul>
</div>
我应该怎么做才能解决这个问题呢???您需要在模块中将服务添加到提供者中,当然记得导入服务
@NgModule({
declarations: [
AppComponent,
HeaderComponent,
SerachBarComponent,
SearchReasultComponent,
ResultItemComponent
],
imports: [
BrowserModule,
AppRoutingModule,
HttpClientModule,
FormsModule
],
providers: [
ReactiveTwitterService
],
bootstrap: [AppComponent]
})
在您的代码构造函数(private{u twitterService:ReactiveTwitterService){}
中,无法初始化private tweetTag:string
,因此它仍然会失败,@Injectable({providedIn:'root'})
与提供程序的作用不同:[ReactiveTwitterService]
您的服务应作为提供商提供给您的组件或模块。
您可以将其添加到appmodule的提供程序:
数组或单个模块中,并将其注入组件中以供使用。我已经尝试过这一点,但同样的问题,由于使用@Injectable({providedIn:'root'}),因此这不再是强制性的。更新后是否尝试重新启动服务器,我的意思是你需要重新运行ng service
我确信这可以解决你的问题,你需要从服务构造函数中删除private tweetTag:string
,并为它创建setter函数,这就是为什么它仍然在你的代码构造函数中显示错误(private\u twitterService:ReactiveTwitterService){}
无法初始化私有tweetTag:string
,因此它仍然失败,@Injectable({providedIn:'root'})
与提供者:[ReactiveTwitterService]
我已经尝试过这个方法,但是同样的问题,因为使用了@Injectable,这不再是强制性的({providedIn:'root'})