Check if data exists using firebase function

问题

How can I check if the days node exists using Firebase Cloud Function?

Pseudo-code inside index.js:

if(days.exists())
{
    //do something
}

回答1:

// outside of function body
const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

// inside function body
return admin.database().ref('days').once('value').then(snap => {
  if (snap.exists()) {
    // do something
  }
});

来源：https://stackoverflow.com/questions/44849927/check-if-data-exists-using-firebase-function