C# Firebase Admin SDK Push Notifications

Question

I want to send push notifications to a mobile app, so I installed Firebase Admin SDK to my .Net project. I followed the instructions on Firebase docs, but when I call the SendAsync from the SDK, it just hangs. Any idea why it would hang? Am I missing steps?

Here is my API code (Note this is only demo code to get it to work):

public async void SendPushNotification()
        {
            FirebaseApp.Create(new AppOptions()
            {
                Credential = GoogleCredential.FromFile("path to json file"),
            });

            var registrationToken = "fqCo_-tXKvY:APA91bGQ47Q2egnqn4Ml...";

            var message = new FirebaseAdmin.Messaging.Message()
            {
                Token = registrationToken,
            };

            string response = await FirebaseMessaging.DefaultInstance.SendAsync(message);

            Console.WriteLine("Successfully sent message: " + response);
        }

Answer 1

you have a deadlock because SendAsync will never finish. if you are calling from ui thread you need to consider using ConfigureAwait(false) so your snippet will look like below:

public async void SendPushNotification()
    {
        FirebaseApp.Create(new AppOptions()
        {
            Credential = GoogleCredential.FromFile("path to json file"),
        });

        var registrationToken = "fqCo_-tXKvY:APA91bGQ47Q2egnqn4Ml...";

        var message = new FirebaseAdmin.Messaging.Message()
        {
            Token = registrationToken,
        };

        string response = await FirebaseMessaging.DefaultInstance.SendAsync(message).ConfigureAwait(false);

        Console.WriteLine("Successfully sent message: " + response);
    }

Answer 2

The firebaseAdmin messaging throw a token error with the .net libraries hence i tested with Postman and works i was able to send the notifications and I see postman generates a code for Resharper library and was easy to install and use, is better to serialize the message with Json and send as parameter

using Firebase.Auth;
using FirebaseAdmin;
using FirebaseAdmin.Auth;
using Google.Apis.Auth.OAuth2;
using System;
using System.Text;
using System.Collections.Generic;
using System.Linq;
using FirebaseAuth = FirebaseAdmin.Auth.FirebaseAuth;
using FirebaseAdmin.Messaging;
using RestSharp;
using Newtonsoft.Json;

namespace messaging
{
    class Program
    {
        static async System.Threading.Tasks.Task Main(string[] args)
        {

            string token = "dtPMeTshqr??????????????";


            var data = new
            {
                to = token,
                notification = new
                {
                    body = "Nueva notificacion de prueba",
                    title = "Notificacion de prueba",
                },
                priority = "high"
            };

            var json = JsonConvert.SerializeObject(data);

            Sendmessage(json);

        }

        private static string Sendmessage(string json)
        {
            var client = new RestClient("https://fcm.googleapis.com/fcm/send");
            client.Timeout = -1;
            var request = new RestRequest(Method.POST);
            request.AddHeader("Authorization", "key=AAAAexjc2Qg:APx??????????????");
            request.AddHeader("Content-Type", "application/json");
            request.AddParameter("application/json", json, ParameterType.RequestBody);
            IRestResponse response = client.Execute(request);
            Console.WriteLine(response.Content);
            return response.Content;
        } 
    }
}