firebase set failed first argument contains undefined in property

Question

When I create an event, I do this:

export const eventCreate = ({ title, time, location }) => {
  const newPostKey = firebase.database().ref('/events').push().key;
  const update = {};

  const postDetails = {
    eventId: newPostKey,
    title,
    ...
    goingNumber: 1,
    ...
  };

  update[`/events/${newPostKey}`] = postDetails;

  return (dispatch) => {
    firebase.database().ref()
      .update(update)
      .then(() => {
        dispatch({ type: EVENT_CREATE });
      })
      .then(() => newPostKey);
  };
};

in the database:

later when I try to update the goingNumber:

export const eventSave = ({ goingNumber, eventId }) => {    
  return (dispatch) => {
    firebase.database().ref(`/events/${eventId}`)
      .set({ goingNumber })
      .then(() => {
        dispatch({ type: EVENT_SAVE_SUCCESS });
      });
  };
};

I get this error saying:

Answer 1

You're not passing in a value for goingNumber. My guess is that you're looking for

firebase.database().ref(`/events/${eventId}`)
        .child('goingNumber').set(goingNumber )