在 AngularFirestoreCollection<T> 或 Observable 中转换 CollectionReference？

Question

我的正在returnCollectionReference。但是，在我将其转换为 Observable<myObj[]> 以处理数组之前，此方法用于 return a AngularFirestoreCollection<myObj>。

humanCol : AngularFirestoreCollection<Human>;
humanObersArray: Observable<Human[]>;

constructor(private db: AngularFirestore) { }

之前我都是用这种方式。努力获取所有数据。

buildHuman(): Observable<Human[]> {
   this.humanCol = this.db.collection('path');
   return this.humanObersArray = this.humanCol.valueChanges();
}

现在，我使用了可选参数。

buildHuman(param1: string, param2?: string, param3?: string...){ 
  this.db.collection('path', ref => {
  let retVal = ref as any;
  if (param1 != null) { retVal = retVal.where('param1', '==', param1) }
  if (param2 != null) { retVal = retVal.where('param2', '==', param2) }
  if (param3 != null) { retVal = retVal.where('param3', '==', param3) }
  ...
  return retVal; //this return a CollectionReference 
  });
}

如何将 retVal 转换为 AngularFirestoreCollection<T> 或 Observable？

Answer 1

你的函数 buildHuman 没有 return 任何东西。只需 return this.db.collection 电话，您就会收到 AngularFirestoreCollection。或者像以前一样添加调用 valueChanges 以获得 observable:

buildHuman(param1: string, param2?: string, param3?: string): AngularFirestoreCollection<any> {
    return this.afs.collection('users', ref => {
        let retVal = ref as any;
        if (param1 != null) { retVal = retVal.where('param1', '==', param1); }
        if (param2 != null) { retVal = retVal.where('param2', '==', param2); }
        if (param3 != null) { retVal = retVal.where('param3', '==', param2); }
        return retVal;
    });
}

或

buildHuman(param1: string, param2?: string, param3?: string): Observable<any> {
    return this.afs.collection('users', ref => {
        let retVal = ref as any;
        if (param1 != null) { retVal = retVal.where('param1', '==', param1); }
        if (param2 != null) { retVal = retVal.where('param2', '==', param2); }
        if (param3 != null) { retVal = retVal.where('param3', '==', param2); }
        return retVal;
    })
    .valueChanges();
}

在 AngularFirestoreCollection<T> 或 Observable 中转换 CollectionReference？

Convert CollectionReference in AngularFirestoreCollection<T> or Observable?

firebase

typescript

angularfire2

angular

google-cloud-firestore