Develop Reference

How to push notification to client when Firebase has a new entry?

I wonder if it's possible to send push notifications to android mobile devices whenever Firebase gets added a new child on specific entity.
For example, let's say there's an entity on Firebase called Tasks. Whenever a new task is added to that firebase collection the "child_added" event is fired and then, in some way, a push notification is sent to a mobile client.
The trigger is the child_added event. However, I'm not sure if is feasible sending push notification right from Firebase events.

You can make a very simple node.js server or a java servlet (based on your language preferences) then using firebase server sdk you can add childEventListener. When value changes you can use FCM to send push notifications using http protocol. I am using this in my app and it is very feasable and reliable.
Note: If you are using this flow for an android app then using java server sdk will be beneficial as it is almost similar to what you have on android.
EDIT: After getting some spotlight on this answer I thought to share some more info regarding same.
//example node.js server as seen on this official firebase blog
var firebase = require('firebase');
var request = require('request');
var API_KEY = "..."; // Your Firebase Cloud Server API key
firebase.initializeApp({
serviceAccount: ".json",
databaseURL: "https://.firebaseio.com/"
});
ref = firebase.database().ref();
function listenForNotificationRequests() {
var requests = ref.child('notificationRequests');
ref.on('child_added', function(requestSnapshot) {
var request = requestSnapshot.val();
sendNotificationToUser(
request.username,
request.message,
function() {
request.ref().remove();
}
);
}, function(error) {
console.error(error);
});
};
function sendNotificationToUser(username, message, onSuccess) {
request({
url: 'https://fcm.googleapis.com/fcm/send',
method: 'POST',
headers: {
'Content-Type' :' application/json',
'Authorization': 'key='+API_KEY
},
body: JSON.stringify({
notification: {
title: message
},
to : '/topics/user_'+username
})
}, function(error, response, body) {
if (error) { console.error(error); }
else if (response.statusCode >= 400) {
console.error('HTTP Error: '+response.statusCode+' - '+response.statusMessage);
}
else {
onSuccess();
}
});
}
// start listening
listenForNotificationRequests();
//example test java servlet which I made just to demonstrate this use case
#WebServlet("/TestServlet")
public class MainServlet extends HttpServlet {
* #see HttpServlet#HttpServlet()
*/
public MainServlet() {
super();
}
/**
* #see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// Get context and then relative path to saved json config file from
// firebase
ServletContext context = getServletContext();
String fullPath = context.getRealPath(FILE_PATH_FOR_JSON_SERVER_AUTH);
// Check if we actually got a file from above path
if (fullPath != null) {
} else {
}
// Setup connection to firebase database here
FirebaseOptions options = new FirebaseOptions.Builder().setServiceAccount(new FileInputStream(fullPath))
.setDatabaseUrl(FIREBASE_DATABSE_URL).build();
// Check to make sure we don't initialize firebase app each time webpage
// is refreshed
if (!exists) {
// If firebase app doesn't exist then initialize it here and set
// exists to true
FirebaseApp.initializeApp(options);
exists = true;
}
// Call this to begin listening *notify* node in firebase database for notifications
addNotificationListener(request, response);
}
/**
* #see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// Build apache httpclient POST request
HttpClient client = HttpClientBuilder.create().build();
HttpPost post = new HttpPost(ENDPOINT_URL);
//Get the required id stored in lastMsgId tree map here
if (!(chatLogs.getLastMsgIdTreeMap().isEmpty())) {
sendToID = chatLogs.getLastMsgIdTreeMap().firstKey();
lstmsg = chatLogs.getLastMsgIdTreeMap().get(sendToID);
}
//Set up a unique id with concatenating sendToID and lstmsg
uniqueID = sendToID + lstmsg;
//Set up a previous id to check with unique id. To avoid instant duplicate notifications
previousID = fcmHelper.getPreviousid();
// Check uniqueId and PreviousID beforeSending
if (!(uniqueID.equals(previousID))) {
fcmHelper.setPreviousid(uniqueID);
//Check if device token and user Id hashmap is not null
if (!(userLogs.getUserIdAndFcmTokenHashMap().isEmpty())) {
//Get the device token of sendTo Id here
deviceToken = userLogs.getUserIdAndFcmTokenHashMap().get(sendToID);
// Create JSON object for downstream data/notification
JSONObject mainNotificationJsonObj = new JSONObject();
JSONObject outerBaseJsonObj = new JSONObject();
try {
// Notification payload has 'title' and 'body' key
mainNotificationJsonObj.put(TITLE, NEW_MESSAGE_RECEIVED);
mainNotificationJsonObj.put(BODY, lstmsg);
mainNotificationJsonObj.put(NOTIFICATION_SOUND, NOTIFICATION_SOUND_TYPE_DEFAULT);
//mainNotificationJsonObj.put(TAG, fcmHelper.getFcmTagId());
System.out.println("This is sentBy id =" + fcmHelper.getFcmTagId());
// This will be used in case of both 'notification' or 'data' payload
outerBaseJsonObj.put(TO, deviceToken);
// Set priority of notification. For instant chat setting
// high will
// wake device from idle state - HIGH BATTERY DRAIN
outerBaseJsonObj.put(PRIORITY_KEY, PRIORITY_HIGH);
// Specify required payload key here either 'data' or
// 'notification'. We can even use both payloads in single
// message
outerBaseJsonObj.put(NOTIFICATION, mainNotificationJsonObj);
} catch (JSONException e) {
e.printStackTrace();
}
// Setup http entity with json data and 'Content-Type' header
StringEntity requestEntity = new StringEntity(outerBaseJsonObj.toString(),
ContentType.APPLICATION_JSON);
// Setup required Authorization header
post.setHeader(AUTHORIZATION, FIREBASE_SERVER_KEY);
// Pass setup entity to post request here
post.setEntity(requestEntity);
// Execute apache http client post response
HttpResponse fcmResponse = client.execute(post);
// Get status code from FCM server to debug error and success
System.out.println(RESPONSE_CODE + fcmResponse.getStatusLine().getStatusCode());
// Get response entity from FCM server and read throw lines
BufferedReader rd = new BufferedReader(new InputStreamReader(fcmResponse.getEntity().getContent()));
StringBuffer result = new StringBuffer();
String line = "";
while ((line = rd.readLine()) != null) {
result.append(line);
}
if (response != null) {
// Print out the response to webpage
PrintWriter out;
out = response.getWriter();
out.println(result);
System.out.println("This is Result - " + result);
}
} else {
//Abort this process if conditions not met
post.abort();
System.out.println(THIS_MSG_ALREADY_SENT);
}
}
}
/*
* This is the main method to be called to setup notifications listener on server startup
*/
private void addNotificationListener(HttpServletRequest request, HttpServletResponse response) {
//Initialize Value event listener
lastMsgListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot arg0) {
// Clear idLastMessagerecivedhash map if not null
if (lastMsgIdTreeMap != null) {
lastMsgIdTreeMap.clear();
}
//Get lastmsg to be sent as notification here
lstmsg = (String) arg0.child(LAST_MESSAGE).getValue();
//Get sendToID here
String sendToID = (String) arg0.child(SEND_TO).getValue();
//Get Sent by ID here
sentBy = (String) arg0.child(SENT_BY).getValue();
//Set fcmTag ID here
fcmHelper.setFcmTagId(sentBy);
//Check if lstmsg is not null
if (lstmsg != null) {
// Create lastmsgTimestampHashMap here
lastMsgIdTreeMap.put(sendToID, lstmsg);
}
//Check for null again
if (lastMsgIdTreeMap != null) {
chatLogs.setLastMsgIdTreeMap(lastMsgIdTreeMap);
}
try {
doPost(request, response);
} catch (ServletException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
#Override
public void onCancelled(DatabaseError arg0) {
}
};
//Set up database reference to notify node here
messageRef = FirebaseDatabase.getInstance().getReference().child(NOTIFY);
//Add value listener to database reference here
messageRef.addValueEventListener(lastMsgListener);
}
"Java servlet is just a personal test. Some parts have been edited or removed to only give an idea about it's setup this is in no way production ready servlet please don't just copy - paste. I encourage you to understand and build your own."

Edit: you should take a look at Firebase Cloud Functions, which let you do that without having to create a Node.js server

Push notifications not received when called inside android app - Amazon SNS

I have a problem with my app based on AWS. When I test the following function in Amazon lambda, everything works (I get the push notification on my phone):
console.log("Loading kupa function");
var AWS = require("aws-sdk");
exports.handler = function(event, context) {
var eventText = JSON.stringify(event, null, 2);
console.log("Received event:", eventText);
var sns = new AWS.SNS();
var params = {
Message: eventText,
Subject: "Test SNS From Lambda",
TopicArn: "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
};
sns.publish(params, context.done);
context.succeed("kupa sukces");
};
However, once I use the following method on my phone I get the "kupa sukces" log into my Android Studio but I don't get the notification on the phone. Furthermore, the "Test" on Lambda does not work anymore as wel...
Here is the code:
String lambdaRequest = "{\n\"kupa\" : \"" + true + "\"\n}";
asyncTask.delegate = wysylaczKupy.this;
asyncTask.friendFunction("friendsRequest",lambdaRequest);
}
the friendFunction is here:
public static void friendFunction(String funName, String requestContent) {
final String functionName = funName;
final String requestPayload = requestContent;
new AsyncTask<Void, Void, InvokeResult>() {
#Override
protected InvokeResult doInBackground(Void... params) {
try {
final ByteBuffer payload =
ENCODER.encode(CharBuffer.wrap(requestPayload));
final InvokeRequest invokeRequest =
new InvokeRequest()
.withFunctionName(functionName)
.withInvocationType(InvocationType.RequestResponse)
.withPayload(payload);
final InvokeResult invokeResult =
AWSMobileClient
.defaultMobileClient()
.getCloudFunctionClient()
.invoke(invokeRequest);
return invokeResult;
} catch (final Exception e) {
Log.e("LAMBDA", "AWS Lambda invocation failed : " + e.getMessage(), e);
final InvokeResult result = new InvokeResult();
result.setStatusCode(500);
result.setFunctionError(e.getMessage());
return result;
}
}
}
How can I fix this?
Thank you in advance,
Jan

Jan,
The Lambda function for publishing to an SNS Topic wasn't quite right. I modified your function and provided a default json value for testing. Just put your TopicARN in and try it out. Once you have tested using the Lambda console, then try the Android code, which I did not try.
Note that when sending a JSON payload to an SNS Topic, a default value is required. The default value is used when you don't specify a protocol specific message. For example, you are publishing to an SNS Topic with Android GCM endpoints and since your JSON payload does not contain "GCM" then all endpoints will receive your default message that you provided.
I'm not sure what you were doing with "{\n\"kupa\" : \"" + true + "\"\n}" but I'm guessing the "kupa": "true" is intended to the the data key/value for the app to handle? If so, you'll need to lookup a proper GCM payload to send both a message and data.
//Pass in the following json for testing: { "default":"some message", "kupa": "true"}
console.log("Loading kupa function");
var AWS = require("aws-sdk");
exports.handler = function(event, context, callback) {
var eventText = JSON.stringify(event, null, 2);
console.log("Received event:", eventText);
var sns = new AWS.SNS();
var params = {
Message: eventText,
MessageStructure: "json",
Subject: "Test SNS From Lambda",
TopicArn: "arn:aws:sns:us-west-2:xxxxxxxxxx:test"
};
sns.publish(params, function (err, data) {
if(err){
callback(err, null); //failed
}
callback(null, "kupa sukces"); //success
});
};

How to call Parse Cloud Code functions from my Android application?

I have already uploaded the function on parse using parse deploy command and i have a data class named Review along with few entries which is displaying in my Parse Core Dashboard.Here is my cloud code function:
Parse.Cloud.define("averageStars", function(request, response) {
var query = new Parse.Query("Review");
query.equalTo("movie", request.params.movie);
query.find({
success: function(results) {
var sum = 0;
for (var i = 0; i < results.length; ++i) {
sum += results[i].get("stars");
}
response.success(sum / results.length);
},
error: function() {
response.error("movie lookup failed");
}
});
});
Here is my Android Function:
HashMap<String, Object> params = new HashMap<String, Object>();
params.put("movie", "The Matrix");
ParseCloud.callFunctionInBackground("averageStars", params, new FunctionCallback<Float>() {
public void done(Float ratings, ParseException e) {
//done action
}
});
This is what i am getting in the log:
NO RESPONSE:ParseRequestException: invalid session token
Please help.

Try including Parse.Cloud.useMasterKey(); in your cloud code function. Also make sure that you have correctly implemented logging in the user from which the cloud function is called.

Android: How to input values to Parse cloud code, eg beforesave

Inside a app, users will upload slot results with period name to the Parse Database. However, before upload, it would be much preferred if beforesave, checked whether the period ref is already there, if the same period ref is existing in the DB, the slot result would not be uploaded.
Cloud.beforesave
Parse.Cloud.beforeSave("check_duplicate", function(request, response)
{
var DB = Parse.Object.extend("Record_db");
var query = new Parse.Query(DB);
query.equalTo("period_ref", request.object.get("period_ref"));
query.first
({
success: function(object)
{
if (object)
{
response.error("A Period with this ref already exists.");
}
else
{
response.success();
}
},
error: function(error)
{
response.error("Could not validate uniqueness for this period ref object.");
}
});
});
Android code:
ParseCloud.callFunctionInBackground("check_duplicate", new HashMap<String, Object>(), new FunctionCallback<String>() {
public void done(String result, ParseException e)
{
if (e == null)
{
Utilities.custom_toast(CurrentResult.this, "cloud success" + result, "gone!", "short");
}
else
{
Utilities.custom_toast(CurrentResult.this, "cloud error" + e, "gone!", "short");
}
}
});
Question:
There is no clear example for such common situation. I would like to ask
for example, now the user would like to upload slot ref 001/2015 results. All info are already available at device, how could I pass this period reference 001/2015 to the cloud code for checking whether it is already existing in the Cloud DB uploading and saving to the Cloud DB?
Thanks a lot!

your first line of Android...
ParseCloud.callFunctionInBackground("check_duplicate", new HashMap(), new FunctionCallback() {
becomes
ParseCloud.callFunctionInBackground("check_duplicate",
new HashMap<String, String>{"period_ref":"001/2015"};,
new FunctionCallback<String>() {

Parse.com ParseQuery inconstancy

I have a very weird situation. I have an application where I am implementing a "Notification History".
I have a separate application that sends push notifications to targeted channels and then creates an entry into a table called Notifications, saving the channel that was targeted and the message that was sent.
channels = channelEditText.getText().toString();
message = messageEditText.getText().toString();
ParsePush push = new ParsePush();
push.setChannel(channels);
push.setMessage(message);
push.sendInBackground();
channelEditText.setText("");
messageEditText.setText("");
ParseObject notifications = new ParseObject("Notifications");
notifications.add("channels", channels);
notifications.put("msg", message);
notifications.saveInBackground();
My Android app's "Notification History" fragment then performs
ParseQueryAdapter<ParseObject> notificationAdapter =
new ParseQueryAdapter<ParseObject>(getActivity(), new ParseQueryAdapter.QueryFactory<ParseObject>() {
public ParseQuery<ParseObject> create() {
ParseQuery query = new ParseQuery("Notifications");
query.whereContainedIn("channels", ParseInstallation.getCurrentInstallation().getList("channels"));
query.orderByDescending("createdAt");
return query;
}
});
notificationAdapter.setTextKey("msg");
ListView notificationListView = (ListView) rootView.findViewById(R.id.notificationListView);
notificationListView.setAdapter(notificationAdapter);
My ParseApplication.java subscribes a user to channel: "Welcome" on installation so I don't receive a null pointer. The Notifications Table entry with channel "Welcome" populates the listview.
I have two ways to subscribe to a channel. One way is on the device itself like this
final EditText syncInput = (EditText) rootView.findViewById(R.id.syncInput);
Button syncButton = (Button) rootView.findViewById(R.id.syncButton);
syncButton.setOnClickListener(new OnClickListener() {
public void onClick(View v){
String sync = null;
sync = syncInput.getText().toString();
PushService.subscribe(getActivity(), sync, DashboardActivity.class);
syncInput.setText("");
}
});
The other way is through CloudCode
Parse.Cloud.define("subscribeToChannel", function(request, response){
var channelName = request.params.channel;
var userId = request.params.userId;
if(!channelName) {
response.error("Missing parameter: channel");
return;
}
if (!userId) {
response.error("Missing paremeter: userId");
return;
}
//Create a Pointer to the user based on their object id
var user = new Parse.User();
user.id = userId;
Parse.Cloud.useMasterKey();
// A user might have more than one installation
var query = new Parse.Query(Parse.Installation);
query.equalTo("user", user); //Match Installations with a pointer to this User
query.find({
success: function(installations) {
for (var i = 0; i < installations.length; i++) {
//Add the channel to al the installations for this user
installations[i].addUnique("channels", channelName);
}
//Save all the installations
Parse.Object.saveAll(installations, {
success: function(installations) {
//All the installations where saved.
response.success("All the installations were updated with this channel.");
},
error: function(error) {
//An error occured while saving one of the objects.
console.error(error);
response.error("An error occured while updating this user's installations.");
}
});
},
error: function(error) {
console.error(error);
response.error("An error occurred while looking up this user's installations");
}
});
});
Both ways of subscribing are successful in that a Push notification sent to the target channel reaches the device. Here is the issue... If I use the device to subscribe my query will show the messages sent to that channel that is saved in the Notifications table. If I use the CloudCode my query does NOT show the message sent to the channel that is saved in the Notification table.
I'm stumped. Any help is deeply appreciated.
--------------------------------SOLUTION-------------------------------------------------
protected void onResume() {
super.onResume();
ParseInstallation.getCurrentInstallation().refreshInBackground(new RefreshCallback(){
#Override
public void done(ParseObject parseObject, ParseException e) {
List<String> channels = ParseInstallation.getCurrentInstallation().getList("channels");
for (int i = 0; i < channels.size(); i++) {
Log.w("TEST", channels.get(i));
}
}
});
}

You're editing the Installation record on the server-side in Cloud Code, but the device isn't getting the updated data. If this is a common behavior in your app, refresh the installation object when you load the app:
ParseInstallation.getCurrentInstallation().refreshInBackground();
or fetchInBackground, as shown here: https://parse.com/docs/android_guide#objects-retrieving
This could also be solved by, instead of querying from the device, calling a cloud function which does the query (with the updated channels list already on the server-side.)