MongoDB c#驱动创建索引

Question

我刚刚将我的MongoDB从2.5.0更新到2.7.0.Visual Studio告诉我,当我想创建这样的索引时:

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

已经过时了.他们希望我们使用CreateIndexModel 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能够实现同样功能的例子.

我试过了:

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);
}

我一直得到以下异常:

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

Answer 1

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));
await IMongoCollection.Indexes.CreateOneAsync(indexModel, cancellationToken: cancellationToken).ConfigureAwait(false);

Answer 2

对于带有索引选项的 BsonDocument 有一个类型不安全的方法：

var indexBuilder = Builders<BsonDocument>.IndexKeys;
var keys = indexBuilder.Ascending("timestamp");
var options = new CreateIndexOptions
{
    Name = "expireAfterSecondsIndex",
    ExpireAfter = TimeSpan.MaxValue
};
var indexModel = new CreateIndexModel<BsonDocument>(keys, options);

// .NET full framework
// .NET Standard library:
await collection.Indexes
                .CreateOneAsync(indexModel, cancellationToken: cancellationToken)
                .ConfigureAwait(false);

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