I am updating an object in firebase using React js. I'm using this boilerplate as reference.
updateBookList: (id, data) => {
return firebaseDb.ref('NewBooks').child(id).update(data).then(() => {
return {};
}).catch(error => {
return {
errorCode: error.code,
errorMessage: error.message
}
});
},
The following updates the Books fine.
What I want to do is return the result instead of returning a blank {}. How can I return the result of what I updated?
This is how I fetch books:
fetchBooks: () => {
return new Promise((resolve, reject) => {
const bookSub = firebaseDb.ref('NewBooks').on("value", books => {
resolve(books.val());
}, error => {
reject(error);
})
})
},
If you want to return the value, you need to retrieve it. You can do that using once and the value event, which returns a promise that resolves to a Firebase snapshot:
updateBookList: (id, data) => {
let ref = firebaseDb.ref('NewBooks');
return ref
.child(id)
.update(data)
.then(() => ref.once('value'))
.then(snapshot => snapshot.val())
.catch(error => ({
errorCode: error.code,
errorMessage: error.message
}));
}
Also, you could simplify your fetchBooks by using once there, too:
fetchBooks: () => {
return firebaseDb.ref('NewBooks')
.once("value")
.then(snapshot => snapshot.val());
}
once returns a promise, so you don't have to create your own and you won't have a dangling event listener. The call to on in your implementation of fetchBooks will see a listener added with each call and multiple calls to resolve will be attempted if the database changes.