How to send FCM notification with an image to all devices using C#?

Question

Is there any way to broadcast an FCM notification--plus an image--to all devices, using C#?

Instead of sending to one specific device ID, I want to include an image and send to all devices over Firebase Notification service.

I used this code to send data to a single user device, but without an image:

public string SendNotificationInstaTips(string firebaseID, 
        string notTitle
        string notText, 
        string notContent)
    {

        try
        {
            string SERVER_API_KEY = "AIza..QXq5OQCaM";
            string SENDER_ID = "162..09";                
            string REGISTERATION_ID = firebaseID;

            WebRequest tRequest = WebRequest.Create("https://fcm.googleapis.com/fcm/send");
            tRequest.Method = "post";
            tRequest.ContentType = "application/json";

            var data = new
            {
                to = REGISTERATION_ID,

                data = new
                {
                    title = notTitle,
                    text = notText
                    content = notContent
                }
            };
            var serializer = new JavaScriptSerializer();
            var json = serializer.Serialize(data);
            Byte[] byteArray = Encoding.UTF8.GetBytes(json);
            tRequest.Headers.Add(string.Format("Authorization: key={0}", SERVER_API_KEY));
            tRequest.Headers.Add(string.Format("Sender: id={0}", SENDER_ID));
            tRequest.ContentLength = byteArray.Length;
            using (Stream dataStream = tRequest.GetRequestStream())
            {
                dataStream.Write(byteArray, 0, byteArray.Length);
                using (WebResponse tResponse = tRequest.GetResponse())
                {
                    using (Stream dataStreamResponse = tResponse.GetResponseStream())
                    {
                        using (StreamReader tReader = new StreamReader(dataStreamResponse))
                        {
                            String sResponseFromServer = tReader.ReadToEnd();
                            return sResponseFromServer;
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            return ex.Message;
        }
    }

did to find any solution to send data to all users ? – Ahmad Aug 29 '20 at 18:58 — Ahmad, Aug 29 '20 at 18:58

score 0 · Answer 1 · answered Feb 22 '17 at 10:06

0

I've been working on this with PHP but it should be similar in C#. Use "registration ids" instead of "to" in your code

var data = new
        {
            to = REGISTERATION_ID, //Change this line

            data = new
            {
                title = notTitle,
                text = notText
                content = notContent
            }
        };
var data = new
        {
            registration_ids = {"AIza..QXq5OQCaM","An2i..QXq5OQCaM", .....},

            data = new
            {
                title = notTitle,
                text = notText
                content = notContent
            }
        };

hope this helps

answered Feb 22 '17 at 10:06

Exairie

1
1

I don't have all of them IDs – Salar Rastari Feb 22 '17 at 10:33
This doesn't really answer the question. The main concern is how to send *images* to all devices. – AL. Feb 22 '17 at 10:43
Well in case you want to send the message to multiple device, this is the way. But for images, you cant. You can send the image's url instead (see AL's answer) – Exairie Feb 23 '17 at 02:26

score 0 · Answer 2 · edited May 23 '17 at 11:46

This is not the usual use-case for Push Notifications. For FCM, it is strongly advised not to send over images, primarily because of the payload size limit - 2KB for notification, 4KB for data.

I suggest using Firebase Storage for storing the images, then downloading it in the device when needed, just sending the download URL in the push notification instead as a workaround.

For your question on how to send to multiple devices, see my answer here. What I would suggest for your use-case to use Topic Messaging.

How to send FCM notification with an image to all devices using C#?

2 Answers2