MongoDB C# 驱动程序创建索引

我刚刚将 MongoDB 从版本 2.5.0 更新到 2.7.0。 Visual Studio 告诉我以下创建索引的方法已过时：

protected override Task OnPerformMaintenanceAsync(CancellationToken cancellationToken) 
    => NotificationLogs.Indexes
                       .CreateOneAsync(Builders<NotificationLog>.IndexKeys
                                                                .Ascending(_ => _.TimestampUtc));

它建议我使用创建索引模型 https://mongodb.github.io/mongo-csharp-driver/2.6/apidocs/html/T_MongoDB_Driver_CreateIndexModel_1.htm.

唯一的问题是我找不到一个可以实现相同功能的示例。

I tried:

protected Task OnPerformMaintenanceTestAsync(CancellationToken cancellationToken)
{
  // Old approach
  var builder = Builders<NotificationLog>.IndexKeys
                                         .Ascending(x => x.TimestampUtc);

  // New approach
  var indexModel = new CreateIndexModel<NotificationLog>(nameof(NotificationLog.TimestampUtc));
  
  return NotificationLogs.Indexes.CreateOneAsync(indexModel);
}

但我得到以下异常：

System.FormatException: 'JSON reader was expecting a value but found 'TimestampUtc'.'

MongoDB 2.7 驱动程序中的新方法是执行以下操作：

var notificationLogBuilder = Builders<NotificationLog>.IndexKeys;
var indexModel = new CreateIndexModel<NotificationLog>(notificationLogBuilder.Ascending(x => x.TimestampUtc));

// .NET Full framwork:
// .NET Standard library:
await IMongoCollection.Indexes
                      .CreateOneAsync(indexModel, cancellationToken: cancellationToken)
                      .ConfigureAwait(false);

// .NET Core:
await IMongoCollection.Indexes
                      .CreateOneAsync(indexModel, cancellationToken: cancellationToken)