如何使用angularfire2和angular5从firebase获取单个值？

Question

I am trying to obtain and display a single value from firebase.

My firebase structure looks like this:

My current .ts file looks like:

storestat$: Observable<any[]>;

constructor(afDb: AngularFireDatabase) {
     this.storestat$ = afDb.list<any>('MyShop').snapshotChanges();
}

I want to display the storeStatus value within the html using {{}} binding. Something like the following:

<button>{{ storeStatus }} Status</button>

I tried using the following initially:

<ng-container *ngFor="let s of storestat$ | async">...
<button>{{ s.storeStatus }}</button>

but of course that wouldn't work.

I tried searching for answers but they just didn't seem quite relevant as they were all pointing to obtaining multiple specific values from lists.

I am using angularfire2 and angular5.

I am new to angular5 so any help would be appreciated, including any educational pointers.

Answer 1

I have a workaround but not sure if it is the best solution. my new .ts file relevant portion looks like:

    this.storestat$ = afDb.list<any>('myshop').snapshotChanges()
       .map(
            changes => {
               return changes.map(
                  c => ({ val: c.payload.val(), 
                          key: c.payload.key,
                          ...c.payload.val()
                   })
               );
       });

and my .html relevant portion now looks like:

<ng-container *ngFor="let s of storestat$ | async">

  <button *ngIf="s.key == 'storeStatus'">{{ s.val }} Status</button>

</ng-container>

I don't think this is the cleanest solution as the database call maps the unwanted Current Orders branch as well, but it works.

Answer 2

If you are not care about the push keys you can use .valueChanges() and it should work like this

afDb.list<any>('myshop').valueChanges().subscribe(value => 
{
    this.storestat$ = value;
});

and in html

<ng-container *ngFor="let s of storestat$">

  <button>{{ s.storeStatus }} Status</button>

</ng-container>