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【HAVENT原创】Firebase 相干操作及代码示例

发布时间:2010-05-20 14:01:29 文章来源:www.iduyao.cn 采编人员:星星草
【HAVENT原创】Firebase 相关操作及代码示例

今天需要对 Firebase 增加删除功能,代码精简如下:

 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 diff
25 
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 DataSnapshot
var 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);  // false
usersRef.isEqual(rootRef.child("users"));  // true
usersRef.parent.isEqual(rootRef);  // true
var rootRef = admin.database().ref();
var usersRef = rootRef.child("users");
var usersQuery = usersRef.limitToLast(10);

usersQuery.isEqual(usersRef);  // false
usersQuery.isEqual(usersRef.limitToLast(10));  // true
usersQuery.isEqual(rootRef.limitToLast(10));  // false
usersQuery.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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