Firebase按键未定义

Question

I am looking to get the the key from a firebase push command when using cloud functions.

const params = {
    date: Date.now(),
    movie,
    movieId: movie.id,
    userId: user.uid,
    group: 'home',
    type: 'watched'
};

const pastRef = event.data.adminRef.root.child(`pastActivity/${user.uid}`);

var newPostRef = pastRef.push().set(params);

var postId = newPostRef.key;

console.log(postId); //undefined

The postId however comes back as undefined. Have try a few other suggested methods without any results.

Answer 1

Reference.set() returns a void promise that resolves when the write operation completes. You can't get the key of it. Instead, split the push() and set(...) into separate statements, so that you can capture the reference

var newPostRef = pastRef.push();
newPostRef.set(params);

var postId = newPostRef.key;

console.log(postId); //undefined

Answer 2

A shorter version can be used if you don't need the newPostRef variable

//var newPostRef = pastRef.push().set(params);
//var postId = newPostRef.key;

const newPostRefKey = pastRef.push(params).key
//this pushes the data and returns the key