push_notification.go

func SendPushNotification(deviceTokens []string) error {
   decodedKey, err := getDecodedFireBaseKey()
   
   if err != nil {
      return err
   }
  
  opts :=  []option.ClientOption{option.WithCredentialsJSON(decodedKey)}
  
  app, err := firebase.NewApp(context.Background(), nil, opts...)
  
  if err != nil {
     log.Debug("Error in initializing firebase : %s", err)
     return err
  }
  
  fcmClient, err := app.Messaging(context.Background())
 
  if err != nil {
     return err
  }
  
  response, err := fcmClient.SendMulticast(context.Background(), &messaging.MulticastMessage{
   Notification: &messaging.Notification{
     Title: "Congratulations!!",
     Body:  "You have just implement push notification",
   },
   Tokens: deviceTokens,
  })
  
  if err != nil {
     return err
  }
  
  log.Debug("Response success count : ", response.SuccessCount)
  log.Debug("Response failure count : ", response.FailureCount)
  
  return nil
}

@nidhi-canopas I am trying to integrate this code in my project and getting following error.

error := SenderId mismatch

Following is the function where I have read server account key file which is generated from firebase messaging service account section.

func getDecodedFireBaseKey() ([]byte, error) {

decodedKey, err := ioutil.ReadFile("server_account_key.json")
if err != nil {
	log.Fatal(err)
}
return decodedKey, nil

}

Please help to resolve the issue.