Firebase related operations and code examples

Today we need to add the deletion function to Firebase. The code is simplified as follows:

 1 var admin = require('firebase-admin'); 2 var config = require('./config.json'); 3  4 var defaultAppConfig = { 5     credential: admin.credential.cert(config.firebase.cert), 6     databaseURL: config.firebase.databaseURL 7 }; 8  9 10 var defaultAppName = 'GoPeople-NodeJS-Admin';11 var defaultApp = admin.initializeApp(defaultAppConfig, defaultAppName);12 13 var signaturesRef = defaultApp.database().ref('signatures');14 15     signaturesRef.orderByChild("isChecked").equalTo(true).limitToLast(10).once("value")16         .then(function(snapshot) {17 18             snapshot.forEach(function(childSnapshot) {19                 var key = childSnapshot.key;20                 var childData = childSnapshot.val();21 22                 var now = new Date();23                 var date = new Date(childData.date);24                 var dayDiff = parseInt((now - date) / (1000 * 60 * 60 * 24)); // day diff25 26                 if(dayDiff >30){27                     signaturesRef.child(key).remove(function(error) {28                         console.log(key);29                         console.log(dayDiff);30                         console.log(error ? ("Uh oh! " + error) : "Success!");31                     });32                 }else{33                     console.log(key);34                     console.log(dayDiff);35                 }36             });37 38         });

Firebase modification node:

function finishJobSync(jobGuid) {var signaturesRef = defaultApp.database().ref('signatures').child(jobGuid);
    signaturesRef.update({isChecked: true},function(error) {if (error) {
            logger.error(error);
        } else {
            logger.info('Job ' + jobGuid + ' signature has been synced.');
        }
    });
}

Firebase listening:

var signaturesRef = defaultApp.database().ref('signatures');

signaturesRef.orderByChild("isChecked").equalTo(false).on("child_added", function(snapshot, prevChildKey) {// TODO: });

admin.database.DataSnapshot

>> key

// Assume we have the following data in the Database:{  "name": {"first": "Ada","last": "Lovelace"
  }
}var ref = admin.database().ref("users/ada");
ref.once("value")
  .then(function(snapshot) {var key = snapshot.key; // "ada"var childKey = snapshot.child("name/last").key; // "last"
  });

>> child

var rootRef = admin.database().ref();
rootRef.once("value")
  .then(function(snapshot) {var key = snapshot.key; // nullvar childKey = snapshot.child("users/ada").key; // "ada"
  });

>> exists

// Assume we have the following data in the Database:{  "name": {"first": "Ada","last": "Lovelace"
  }
}// Test for the existence of certain keys within a DataSnapshotvar ref = admin.database().ref("users/ada");
ref.once("value")
  .then(function(snapshot) {var a = snapshot.exists();  // truevar b = snapshot.child("name").exists(); // truevar c = snapshot.child("name/first").exists(); // truevar d = snapshot.child("name/middle").exists(); // false
  });

>> foreach

// Assume we have the following data in the Database:{  "users": {"ada": {      "first": "Ada",      "last": "Lovelace"},"alan": {      "first": "Alan",      "last": "Turing"}
  }
}// Loop through users in order with the forEach() method. The callback// provided to forEach() will be called synchronously with a DataSnapshot// for each child:var query = admin.database().ref("users").orderByKey();
query.once("value")
  .then(function(snapshot) {
    snapshot.forEach(function(childSnapshot) {      // key will be "ada" the first time and "alan" the second time  var key = childSnapshot.key;      // childData will be the actual contents of the child  var childData = childSnapshot.val();
  });
});

>> hasChildren

// Assume we have the following data in the Database:{  "name": {"first": "Ada","last": "Lovelace"
  }
}var ref = admin.database().ref("users/ada");
ref.once("value")
  .then(function(snapshot) {var a = snapshot.hasChildren(); // truevar b = snapshot.child("name").hasChildren(); // truevar c = snapshot.child("name/first").hasChildren(); // false
  });

>> numChildren

// Assume we have the following data in the Database:{  "name": {"first": "Ada","last": "Lovelace"
  }
}var ref = admin.database().ref("users/ada");
ref.once("value")
  .then(function(snapshot) {var a = snapshot.numChildren(); // 1 ("name")var b = snapshot.child("name").numChildren(); // 2 ("first", "last")var c = snapshot.child("name/first").numChildren(); // 0
  });

admin.database.Query

>> startAt, endAt

// Find all dinosaurs that are at least three meters tall.var ref = admin.database().ref("dinosaurs");
ref.orderByChild("height").startAt(3).on("child_added", function(snapshot) {
  console.log(snapshot.key)
});// Find all dinosaurs whose names come before Pterodactyl lexicographically.var ref = admin.database().ref("dinosaurs");
ref.orderByKey().endAt("pterodactyl").on("child_added", function(snapshot) {
  console.log(snapshot.key);
});

>> ; limitToFirst, limitToLast

// Find the two shortest dinosaurs.var ref = admin.database().ref("dinosaurs");
ref.orderByChild("height").limitToFirst(2).on("child_added", function(snapshot) {  // This will be called exactly two times (unless there are less than two
  // dinosaurs in the Database).

  // It will also get fired again if one of the first two dinosaurs is
  // removed from the data set, as a new dinosaur will now be the second
  // shortest.  console.log(snapshot.key);
});// Find the two heaviest dinosaurs.var ref = admin.database().ref("dinosaurs");
ref.orderByChild("weight").limitToLast(2).on("child_added", function(snapshot) {  // This callback will be triggered exactly two times, unless there are
  // fewer than two dinosaurs stored in the Database. It will also get fired
  // for every new, heavier dinosaur that gets added to the data set.  console.log(snapshot.key);
});

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