Question

我已经完成了获取数组的搜索，然后在输入时过滤了它的名称。如果我写static，一切都很好：

export class AddComponent {
  protected dataService: CompleterData;
  protected searchData = [
    {name: '84A4DA'},
    {name: '846ASD'},
    {name: '8444AS'},
]
constructor(private completerService: CompleterService, private router: Router, public back: BackService,
             ) {
this.dataService = completerService.local(this.searchData, 'name', 'name');
}

但是当我尝试从db firebase中创建searchData时：

getArray(): void {
    this.afDatabase.list('/imones')
      .valueChanges()
      .subscribe(res => {
        console.log(res)//should give you the array of percentage.
        this.array = res;
      })
}

this.searchData = this.back.getArray();
  constructor(private completerService: CompleterService, private router: Router, public back: BackService,
             ) {
    this.dataService = completerService.local(this.searchData, 'name', 'name');
}

我收到错误消息：

如何解决？

Answer 1

问题在于，在构造函数中，this.SearchData不是数组。原来如此。 1.-您的服务必须可观察到。不订阅服务 2.-将代码从构造函数移动到ngInit 3.-在订阅函数中，您具有searchData的值

很难为我理解您的代码，但是，如果您的服务返回Observables-而不是data-，我相信您的组件可以像

constructor(private completerService: CompleterService, 
            private router: Router, public back: BackService){}
ngOnInit()
{
  this.back.getArray().subscribe(res=>{
      this.searchData=res;
      completerService.local(this.searchData, 'name', 'name').subscribe(res=>
      {
          this.dataService=res;
      });
  })
}

//Or , better, using switchMap
ngOnInit()
{
  this.back.getArray().pipe(switchMap(res=>{
      this.searchData=res;
      return completerService.local(this.searchData, 'name', 'name')
      }))
      .subscribe(res=>
      {
          this.dataService=res;
      });
}

Answer 2

getArray（）方法不返回任何数组，但是当您订阅afDatabase.list时，您将获得一个我假定的值数组，因此在subscription回调中，应将值分配给您的数组。

getArray(): void {
this.afDatabase.list('/imones')
  .valueChanges()
  .subscribe(res => {
    console.log(res)//should give you the array of percentage.
    this.searchData = res;
  })}

或者如果您正在逐一获取值，请写

getArray(): void {
    this.afDatabase.list('/imones')
      .valueChanges()
      .subscribe(res => {
        console.log(res)//should give you the array of percentage.
        this.searchData.push(res); //searchData must be initialized as empty array
      })
}

Angular 6如何将数据提供为无效数组

2 个答案: