Question

我正在学习Angular 2，我需要将我的服务结果分配给组件构造函数中的数据变量。如何在构造函数中使用订阅数据并将此值分配给我的公共数据数组？

public data: Array<any> =[];

public constructor(private _languageService: LanguageService){

    this._languageService.getLanguages()
    .subscribe(languages => {this.languages =languages;}
        ,error => this.errorMessage = <any>error)

    this.length = this.data.length;
    //How i can set  this.data = this.languages  
    //if  this.languages is empty outside the subscribe?
}

如果有人能向我解释如何将服务返回的数据分配给变量，我真的很感激。

Answer 1

我们必须在.subscribe()

中分配所有值

public data: Array<any> =[];

public constructor(private _languageService: LanguageService){

    this._languageService
        .getLanguages()
        .subscribe(languages => {
            this.languages =languages;
            [].push.apply(this.data, languages);
        },error => this.errorMessage = <any>error)

    ...
}

构造[].push.apply(target, source)会将所有即将到来的值推送到现有数组引用

EXTEND

我们可以通过 observable 源加载数据，然后在可用时使用。我们在模板中使用*ngIf

<div>
   <some-component
      *ngIf="myData"
       [bindSource]="myData"
       ...
   ></some-component>
</div>

在组件中我们可以订阅获取该数据：

public myData: any[] =[];

public constructor(private _languageService: LanguageService){

    this._languageService
        .getLanguages()
        .subscribe(languages => {
            this.myData = languages;
        });
}

如何在Angular 2构造函数中分配订阅数据？

1 个答案: