用C#读取MongoDB中的字段值

using MongoDB.Bson;
using MongoDB.Driver;

public class MongoDBExample
{
    private IMongoCollection<BsonDocument> collection;

    public MongoDBExample()
    {
        // 连接MongoDB数据库
        var client = new MongoClient("mongodb://localhost:27017");
        var database = client.GetDatabase("mydb");
        collection = database.GetCollection<BsonDocument>("mycollection");
    }

    public string ReadFieldValue(string fieldName)
    {
        // 构建查询条件
        var filter = Builders<BsonDocument>.Filter.Empty;

        // 查询并获取结果
        var result = collection.Find(filter).FirstOrDefault();

        // 读取字段值
        var fieldValue = result.GetValue(fieldName).ToString();

        return fieldValue;
    }
}

// 使用示例
var example = new MongoDBExample();
var fieldValue = example.ReadFieldValue("fieldName");
Console.WriteLine(fieldValue);