在 AngularFirestoreCollection<T> 中转换 CollectionReference或可观察的? [英] Convert CollectionReference in AngularFirestoreCollection&lt;T&gt; or Observable?

问题描述

我的方法正在返回一个CollectionReference.但是，在我将其转换为 Observable 以处理数组之前，此方法用于返回 AngularFirestoreCollection.

My method is returning a CollectionReference. However, this method used to return a AngularFirestoreCollection<myObj> before I converted it to Observable<myObj[]> to work with arrays.

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

constructor(private db: AngularFirestore) { }

之前我是用这种方式的.出色地获取所有数据.

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 或 Observable?

How I can to convert retVal to AngularFirestoreCollection<T> or Observable?

推荐答案

您的函数 buildHuman 不返回任何内容.只需返回 this.db.collection 调用，您就会得到一个 AngularFirestoreCollection.或者像之前一样添加 call valueChanges 以获得 observable:

Your function buildHuman doesn't return anything. Just return the this.db.collection call and you get a AngularFirestoreCollection. Or add call valueChanges like before to get an 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();
}

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