如何使用C#驱动程序从现有的Mongo索引定义创建Mongo索引定义？

using MongoDB.Driver;

var connectionString = "mongodb://localhost:27017";
var client = new MongoClient(connectionString);
var database = client.GetDatabase("mydatabase");

var collection = database.GetCollection<MyDocument>("mycollection");

using MongoDB.Driver;

var keys = Builders<MyDocument>.IndexKeys.Ascending(x => x.FieldName);
var options = new CreateIndexOptions { Unique = true };

var model = new CreateIndexModel<MyDocument>(keys, options);

collection.Indexes.CreateOne(model);

using MongoDB.Driver;

var connectionString = "mongodb://localhost:27017";
var client = new MongoClient(connectionString);
var database = client.GetDatabase("mydatabase");
var collection = database.GetCollection<MyDocument>("mycollection");

var keys = Builders<MyDocument>.IndexKeys.Ascending(x => x.FieldName);
var options = new CreateIndexOptions { Unique = true };
var model = new CreateIndexModel<MyDocument>(keys, options);

collection.Indexes.CreateOne(model);