Angular 2-将数据从服务传递到组件
我创建了一个服务,该服务调用api以获取一些数据.我想将其返回给调用组件.
I have created a service that calls an api to get some data. I want to return this to the calling component.
这就是我所拥有的:
SomeComponent() {
someData = string;
constructor(
private _configService: SomeService
)
{
var value = this._configService.getKey('some-key');
console.log(value);
}
}
然后我有一项服务:
export class ConfigService {
response:any;
constructor(private _http:Http) {}
getConfig(): Observable<any>
{
return this._http.get('src/config/config.json')
.map(response => response.json()).publishLast().refCount();
}
getKey(key:string) {
this.getConfig()
.subscribe(
data => {
if (data[key] != 'undefined')
{
return data[key]
} else {
return false;
}
},
error => {
return false;
}
);
}
}
这个想法是我可以调用方法getKey('some-key'),如果该键存在于返回的json数组中,则返回数据.如果不是,则返回false.
The idea is that I can call the method getKey('some-key') and if the key exists in the returned json array, the data is returned. If not, false is returned.
运行此命令时,我可以看到该对象已在服务中返回,但是没有返回到组件中,而是得到了未定义".
When this runs I can see the object is being returned in the service, however it is not being returned to the component, instead I get "undefined".
如何正确返回此结果?
您的问题是您的处理是异步的,并且您在回调内返回而不是在调用方法内返回.
Your problem is that your processing is asynchronous and you return within the callback not within the calling method.
我将为此使用map
运算符:
getKey(key:string) {
return this.getConfig().map(data => {
if (data[key] != 'undefined') {
return data[key];
} else {
return false;
}
);
}
并在组件中:
SomeComponent() {
someData = string;
constructor(
private _configService: SomeService
) {
this._configService.getKey('some-key').subscribe(value => {
console.log(value);
});
}
}