HTTP请求角2
问题描述:
我想在角2中从外部API发出请求。 我想管理2个文件中的数据请求并将结果显示为json。HTTP请求角2
我的数据输出部分看起来是这样的:
import {Component} from '@angular/core'
import {DataService} from './datavisualisation.service'
@Component({
selector: 'app-datavisualisation-output',
template: `
`
})
export class DatavisualisationOutput {
constructor(dataservice: DataService) {
dataservice.data
.subscribe(
data => this.data = data,
console.error,
() => console.log('Look at this:' + data)
);
}
}
我对服务第二个文件是这样的:
import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import 'rxjs/add/operator/map';
@Injectable()
export class DataService {
constructor(http:Http) {
this.data = http.get('http;//...API')
.map(response => response.json());
}
}
...但控制台显示以下错误:
components/datavisualisation/dataservices/datavisualisation.output.service.ts:12:26
Property 'data' does not exist on type 'DataService'.
components/datavisualisation/dataservices/datavisualisation.output.service.ts:14:29
Property 'data' does not exist on type 'DatavisualisationOutput'.
components/datavisualisation/dataservices/datavisualisation.output.service.ts:16:43 Cannot find name 'data'.
components/datavisualisation/dataservices/datavisualisation.service.ts:8:13
Property 'data' does not exist on type 'DataService'.
我在做什么错在这里?
答
应定义data
财产上的DatavisualisationOutput
组件:
export class DatavisualisationOutput {
public data: any; //this one
constructor(dataservice: DataService) {
dataservice.data
.subscribe(
data => this.data = data,
console.error,
() => console.log('Look at this:' + data)
);
}
}
,并在你的DataService
:
@Injectable()
export class DataService {
public data: any;
constructor(http:Http) {
this.data = http.get('http;//...API')
.map(response => response.json());
}
}
和DatavisualisationOutput
...只是..总是定义您访问任何财产this
。
答
由于@PierreDuc已经表示您应该在组件类中定义该变量,以使其在Class
上下文中可用。
此外,您应该在服务内部创建一个负责数据的方法。只需从另一个组件调用相同的方法,它将返回上次检索到的数据。
代码
@Injectable()
export class DataService {
data: any;
constructor(http:Http) {
}
getData(){
if(this.data) return Observable.of(this.data)
else
return http.get('http;//...API')
.flatMap(response => {
this.data = response.json();
return Observable.of(this.data)
);
}
}
组件
export class DatavisualisationOutput {
myData: any;
constructor(private dataservice: DataService) {
dataservice.data
.subscribe(
data => this.data = data,
console.error,
() => console.log('Look at this:' + data)
);
}
ngOnInit(){
dataservice.getData().subscribe(
data => myData = data
)
}
}