查询后 FirebaseListObservable 变为 Observable [英] FirebaseListObservable becomes Observable after query

问题描述

我在 firebase 上做了一个小应用.我一直在使用 angularfire 提供的一种称为 FirebaseListObservable 的类型，它允许您观察数据的变化.我遇到的问题是 Angularfire 还提供了一种查询数据的方法，方法是将查询对象附加/传递到请求中.

I made a small app on firebase. I have been using a type provided by angularfire called a FirebaseListObservable which allows you to observe changes to your data. The problem I'm having is that Angularfire also provides a way to query the data, by attaching / passing in a query object to the request.

以下返回一个 FirebaseListObservable.

The following returns a FirebaseListObservable.

this.resources$ = <FirebaseListObservable<IResource[]>> this.af.list(`/resources/${this.auth.id}`) as FirebaseListObservable<IResource[]>;

//这将返回一个常规的 observable.

//This returns a regular observable.

this.resources$ = <FirebaseListObservable<IResource[]>> this.af.list(`/resources/${this.auth.id}`,
  {
    query: {
      orderByChild: `${property}`
    }
  }
) as FirebaseListObservable<IResource[]>;

但这会返回一个普通的旧 observable.问题是我需要一个 FirebaseListObservable，因为它添加了 CRUD 功能，我正在尝试编写简单的过滤器/排序方法.

But this returns a plain old observable. The issue is that I need a FirebaseListObservable because it has added CRUD functionality and I'm trying to write simple filter / sorting methods.

我可以看到他们有一个未解决的问题，但我希望迟早有办法解决这个问题.工单中讨论的解决方案描述了扩展 FirebaseListObservable 并覆盖提升方法以返回自定义 observable.我试图创建一个 CustomFirebaseListObservable 来做到这一点，但我似乎无法访问正确的属性(来自我的自定义 observable 中的 observable.source 和 observable.operator.我希望有一种方法可以将 observable 投射到一个 firebaseListObservable.任何解决方法都可以.

I can see they have an Open Issue for this but I'm hoping that there is a way around this issue sooner rather than later. The solution discussed in the ticket describes extending the FirebaseListObservable and overriding the lift method to return the custom observable. I attempted to create a CustomFirebaseListObservable that does just that, but I don't seem to have access to the correct properties (observable.source and observable.operator from within my custom observable. I'm hoping for a way to cast an observable to a firebaseListObservable. Any workaround would do really.

推荐答案

如果您仍然遇到此问题，也许您可​​以使用排序创建 firebase 引用，然后将其传递给 angularfire?

If you are still having this issue, maybe you can create the firebase reference with the ordering and then passing that into angularfire?

let refPath = `/resources/${this.auth.id}`,
    ref = firebase.database().ref(refPath).orderByChild(property);
this.resources$ = <FirebaseListObservable<IResource[]>>this.af.list(ref);

这篇关于查询后 FirebaseListObservable 变为 Observable的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！