问题描述
我有以下代码,我是 mongodb 的新手,我需要帮助来查找集合中的特定元素.
I have the below code and I am new to mongodb, I need help in finding an specific element in the collection.
using MongoDB.Bson; using MongoDB.Driver; namespace mongo_console { public class User { public ObjectId Id { get; set; } public string name { get; set; } public string pwd { get; set; } } class Program { static void Main(string[] args) { MongoClient client = new MongoClient(); MongoServer server = client.GetServer(); MongoDatabase db = server.GetDatabase("Users"); MongoCollection<User> collection = db.GetCollection<User>("users"); User user = new User { Id = ObjectId.GenerateNewId(), name = "*****", pwd = "*****" }; User user2 = new User { Id = ObjectId.GenerateNewId(), name = "system", pwd = "system" }; collection.Save(user); collection.Save(user2); /* * How do I collection.Find() for example using the name */ } } }
一旦我找到我想要打印的用户,这是可能的还是只会找到返回位置?如果是这样,我该如何打印?
Once I find the user I will like to print it, is that posible or will find only return the position? if so, how do I print it?
我看过一些示例 collection.Find(x => x.something) 但我不知道 x 是什么或意味着什么
I have seen some examples collection.Find(x => x.something) but I do not know what that x is or mean
推荐答案
要查找记录,您可以在 find 中使用 Lambda,例如:
To find a record you could use Lambda in find, for example:
var results = collection.Find(x => x.name == "system").ToList();
或者,您可以使用支持强类型 Lambda 或文本的构建器:
Alternatively you can use Builders which work with strongly typed Lambda or text:
var filter = Builders<User>.Filter.Eq(x => x.name, "system")
或
var filter = Builders<User>.Filter.Eq("name", "system")
然后像上面一样使用find
And then use find as above
// results will be a collection of your documents matching your filter criteria // Sync syntax var results = collection.Find(filter).ToList(); // Async syntax var results = await collection.Find(filter).ToListAsync();