.NET Core MongoDB. Find by guid returns null - mongodb

Question

I have the following setup:
The document:
[BsonCollection("Users")] // I get the collection name with a custom extension
[BsonIgnoreExtraElements]
public class UserDocument
{
[BsonId]
public Guid Id { get; set; }
public string UserName { get; set; }
public string Email { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public DateTime DateOfBirth { get; set; }
public UserSettingsModel UserSettings { get; set; }
}
public class UserSettingsModel
{
// ...
}
The repository:
public class UserRepository
{
private readonly IMongoCollection<UserDocument> _collection;
private readonly ILogger<UserRepository> _logger;
public UserRepository(IMongoDatabase database, ILogger<UserRepository> logger)
{
// returns "Users"
var collectionName = typeof(UserDocument).GetCollectionName();
_collection = database.GetCollection<UserDocument>(collectionName);
}
// ...
public async Task<UserDocument> GetById(Guid id)
{
var filter = Builders<UserDocument>.Filter.Eq(x => x.Id, id);
var user = await _collection.FindAsync(filter);
// var user = await _collection.FindAsync(x => x.Id == id); - doesn't work either
var request = filter.Render(
_collection.DocumentSerializer,
_collection.Settings.SerializerRegistry).ToString();
_logger.LogDebug(request);
return user.FirstOrDefault();
}
}
And I initialize the client this way:
// ...
BsonSerializer.RegisterSerializer(new GuidSerializer(GuidRepresentation.Standard));
var client = new MongoClient(connectionString);
var database = client.GetDatabase(dbName);
services.AddSingleton(c => database);
// convention pack and registries
// ...
// if moved here doesn't work either
// BsonSerializer.RegisterSerializer(new GuidSerializer(GuidRepresentation.Standard));
The filter generated in GetById is still the following: { "_id" : CSUUID("459f165a-4a91-4f39-906c-dc7401ee2468") } when I expect it to be UUID instead of CSUUID.
So, the query doesn't find anything and returns null. In the database the document I'm searching for has _id: UUID('459f165a-4a91-4f39-906c-dc7401ee2468')
What am I doing wrong?

Answer 1

I was able to fixing by this trick:
var mongoConnectionUrl = new MongoUrl(connectionString);
var mongoClientSettings = MongoClientSettings.FromUrl(mongoConnectionUrl);
// before initializing client
mongoClientSettings.GuidRepresentation = GuidRepresentation.Standard;
However setting the GuidRepresentation in client settings is obsolete, which is quite confusing. Also, the query generated still has CSUUID instead of UUID. I was able to log the query the following way:
mongoClientSettings.ClusterConfigurator = cb =>
{
cb.Subscribe<CommandStartedEvent>(e => logger.LogDebug($"{e.CommandName} - {e.Command.ToJson()}"));
};
If anyone finds a better way and post it here it would be appreciated.