将存储的 MongoDB 集合文档从 BsonDocument 转换为“MyClass”类型？

Question

我有以下情况。我有两个班Person 和Animal

using System;
using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;
namespace MongoTesting.Documents
{
    public class Person
    {
        [BsonId]
        [BsonRepresentation(BsonType.String)]
        public Guid PersonId { get; set; } = Guid.NewGuid();

        public Guid PetId { get; set; } = Guid.Empty;

        public string Name { get; set; } = "Person";
    }
}

using System;
using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;
namespace MongoTesting.Documents
{
    public class Animal
    {
        [BsonId]
        [BsonRepresentation(BsonType.String)]
        public Guid AnimalId { get; set; } = Guid.NewGuid();

        public bool IsMammal { get; set; }

        public string Description { get; set; } = "Animal";
    }
}

序列化为IMongoCollections

public IMongoCollection<BsonDocument> PersonCollection { get; set; }
public IMongoCollection<BsonDocument> AnimalCollection { get; set; }
...
PersonCollection = Database.GetCollection<BsonDocument>("PersonCollection");
AnimalCollection = Database.GetCollection<BsonDocument>("AnimalCollection");

在这些IMongoCollection<BsonDocument> 类型的集合中，我现在有大量的文档。

---

我最近一直在重构与 MongoDB 相关的代码和查询。我发现我可以将文档保存到具有强类型文档的集合中，例如我现在有了集合

public IMongoCollection<Person> PersonCollection { get; set; }
public IMongoCollection<Animal> AnimalCollection { get; set; }

我可以在其上轻松执行更清晰、更有意义的查询。

---

由于这些更改以及已存储在我的集合中的大量文档，我想将集合中的文档从 BsonDocument 转换为 Person/Animal 文档。

如何将存储的 MongoDB 集合文档从 BsonDocument 转换为特定类类型的文档？

---

Answer 1

刚刚对此进行了测试，我可以确认只要属性名称匹配，C# 驱动程序就会默认处理映射。更复杂的情况（如多态）需要多做一些工作，但本质上，你可以这样做：

//define the collection and a sample BsonDocument:
var collectionName = "bsonDocs";
var bsonDoc = BsonDocument.Parse("{ \"_id\" : ObjectId(\"5b476c4b7d1c1647b06f8e75\"), \"Detail\" : \"testString1\", }");
//Establish connection to database
var clientInstance = new MongoClient();
var db = clientInstance.GetDatabase("TEST");
//Get the collection as BsonDocuments
var collection = db.GetCollection<BsonDocument>(collectionName);
//Insert a BsonDocument
collection.InsertOne(bsonDoc);
//Get the same collection, this time as your data model type
var modelCollection = db.GetCollection<TestDataModel>(collectionName);
//Query that collection for your data models
var models = modelCollection.AsQueryable().FirstOrDefault();
//Write data models to that same collection
modelCollection.InsertOne(new TestDataModel{Detail = "new Item"});

TestDataModel 在哪里：

class TestDataModel
{
    public ObjectId {get;set;}
    public string Detail {get;set;}
}