CODEWITHSUNDEEP
angularfirebasefirebase-realtime-databasepromise
Vik
Vik

Reputation: 9319

returning response from firebase push

i have a code to create a new record in firebase realtime DB as below

assignCoupon(email:string, discType: string, discVal: number, code:string){

    let coupon = {
      "discType" : discType,
      "discVal": discVal,
      "code": code
    }

    this.db.list('/users/' + uid + '/coupons').push(coupon).then(
      (resp) => console.log("user created with:" + resp)
    )

  }

This works fine. But i need to return the response as a promise back to the calling code so that i can show a message to user. unlike snapshotChanges() this does not return a subscribe. So how do i do it in this case? To be clear trying to use the same style as in my below code

getOrderHistory(uid:string){
    console.log('start of getOrderHistory with uid:' + uid)
    return new Promise((resolve, reject) =>
      {
        this.db.object("/users/" + uid + "/orders").snapshotChanges().map(
          (snapshot) => {return snapshot.payload.val()}
        ).subscribe(
          res => {
            //console.log('response:' + res)
            resolve(res)
          },
          err => {
            console.log(err)
            reject(err)
          }
        )
      })
  }

Upvotes: 0

Views: 130

Answers (1)

sketchthat
sketchthat

Reputation: 2688

This answer is outside the scope of your question, your question has been answered in the comments.

Looking at your getOrderHistory function, you can clean up the promise a bit by using rxjs/toPromise.

If you use valueChanges() instead of snapshotChanges() you won't need to map the response, as angularfire2 returns the payload value.

Using the .pipe(first()) method will take the first subscription event (or null if the data doesn't exist) and wrap it as a promise.

This optimised function should do the same thing as your example above and won't leave you with subscriptions that you need to unsubscribe from as the first operator will close the subscription after it's received the first value.

// Import the operator
import { first } from 'rxjs/operators';


getOrderHistory(uid: string) {
    return this.db.object(`/users/${uid}/orders`)
      .valueChanges()
      .pipe(first())
      .toPromise();
  }

Upvotes: 1

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