Firebase query and delete data in javascript

Question

Here is my firebase

I would like to delete the last deed within deeds which happens to be deed id: 1. I would like to do this without specifying anything other than deleting the last deed in deeds.

Here is what I have tried already, but I receive no function errors because i'm returning query type objects.

const deedRef = admin.database().ref('/deeds');
deedRef.limitToLast(1).once("value", (snapshot) => {
    snapshot.val().remove();
})

And

const deedRef = admin.database().ref('/deeds');
deedRef.limitToLast(1).once("value", (snapshot) => {
    snapshot.forEach((deedSnapshot) =>{
         deedSnapshot.remove();
    })
})

And I've tried this

const deedRef = admin.database().ref('/deeds');
deedRef.limitToLast(1).remove();

How can I reference the last deed in deeds and remove it? The last deed will constantly change.

Frank van Puffelen · Accepted Answer · 2018-06-26 04:01:35Z

3

You were getting close:

const deedRef = admin.database().ref('/deeds');
deedRef.limitToLast(1).once("value", (snapshot) => {
    snapshot.forEach((deedSnapshot) =>{
         deedSnapshot.ref.remove();
    })
})

answered Jun 26, 2018 at 4:01

Frank van Puffelen

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3 Comments

Frank van Puffelen Over a year ago

It's easiest to remember that you need a Reference to do any write operations. A DataSnapshot is not a Reference, but you can get is reference by calling ref on it.

Daniel Crowley Over a year ago

Frank would you be charged for an operation like this? (i.e. would it count as "downloaded" data as you've queried for it, even if you haven't accessed any data inside that node?)

Frank van Puffelen Over a year ago

A DataSnapshot contains a snapshot of the data. That means the data is available in the client, so it has been downloaded, and you will be charged for the bandwidth.

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