Example code for Firebase related operations

今天需要对 Firebase 增加删除功能，代码精简如下：

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
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 修改节点：

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 监听：

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; // null
   var 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();  // true
   var b = snapshot.child("name").exists(); // true
   var c = snapshot.child("name/first").exists(); // true
   var 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(); // true
   var b = snapshot.child("name").hasChildren(); // true
   var 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

>> orderByChild

var ref = admin.database().ref("dinosaurs");
ref.orderByChild("height").on("child_added", function(snapshot) {
 console.log(snapshot.key + " was " + snapshot.val().height + " m tall");
});

>> orderByKey

var ref = admin.database().ref("dinosaurs");
ref.orderByKey().on("child_added", function(snapshot) {
 console.log(snapshot.key);
});

>> orderByValue

var scoresRef = admin.database().ref("scores");
scoresRef.orderByValue().limitToLast(3).on("value", function(snapshot) {
 snapshot.forEach(function(data) {
   console.log("The " + data.key + " score is " + data.val());
 });
});

 

>> 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);
});

 >> equalTo

// Find all dinosaurs whose height is exactly 25 meters.var ref = admin.database().ref("dinosaurs");
ref.orderByChild("height").equalTo(25).on("child_added", function(snapshot) {
 console.log(snapshot.key);
});

>> isEqual

var rootRef = admin.database().ref();var usersRef = rootRef.child("users");

usersRef.isEqual(rootRef);  // falseusersRef.isEqual(rootRef.child("users"));  // trueusersRef.parent.isEqual(rootRef);  // true

var rootRef = admin.database().ref();var usersRef = rootRef.child("users");var usersQuery = usersRef.limitToLast(10);

usersQuery.isEqual(usersRef);  // falseusersQuery.isEqual(usersRef.limitToLast(10));  // trueusersQuery.isEqual(rootRef.limitToLast(10));  // falseusersQuery.isEqual(usersRef.orderByKey().limitToLast(10));  // false

 

>> toString

// Calling toString() on a root Firebase reference returns the URL where its// data is stored within the Database:var rootRef = admin.database().ref();var rootUrl = rootRef.toString();// rootUrl === "https://sample-app.firebaseio.com/".// Calling toString() at a deeper Firebase reference returns the URL of that// deep path within the Database:var adaRef = rootRef.child('users/ada');var adaURL = adaRef.toString();// adaURL === "https://sample-app.firebaseio.com/users/ada".

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