Use Realm in a Console App - .NET SDK

Overview

Realm instances and objects are bound to a SynchronizationContext, which means that they can only be accessed on the same thread on which they are created. On platforms with a UI thread, the framework installs a SynchronizationContext on the main thread, allowing you to make reads and writes to the database with asynchronous calls.

However, in console apps, there is no UI thread, and thus no SynchronizationContext installed. This means that if you await an asynchronous Task, a random thread is spun up from the thread pool, from which you can no longer access any previously-opened Realm instances.

To be able to efficiently use Realm between asynchronous calls, you should install a SynchronizationContext - either one you implement yourself, or one provided in a 3rd party library.

Usage

The following code example uses the Realm SDK to add Device Sync to a console application. The app uses the third-party Nito.AsyncEx package to provide an AsyncContext. The Realm code is then run under the AsyncContext.

using System;
using System.Linq;
using System.Threading.Tasks;
using Nito.AsyncEx;
using Realms;
using Realms.Sync;
namespace ConsoleTests
{
    class Program
    {
        const string myRealmAppId = "myAppId";
        public static void Main(string[] args)
        {
            Nito.AsyncEx.AsyncContext.Run(async () => await MainAsync(args));
        }
        private static async Task MainAsync(string[] args)
        {
            var app = App.Create(myRealmAppId);
            var user = await app.LogInAsync(Credentials.Anonymous());
            var config = new PartitionSyncConfiguration("partition", user);
            using var realm = await Realm.GetInstanceAsync();
            var itemsBiggerThanFive = realm.All<Item>().Where(f => f.Size > 5);
            foreach (var item in itemsBiggerThanFive)
            {
                await Task.Delay(10); // Simulates some background work
                Console.WriteLine(item.Size);
            }
        }