c# – MongoDB嵌入式多态对象

发布时间：2020-12-15 03:59:36 所属栏目：百科来源：网络整理

导读：我有一个类似这样的对象： [BsonKnownTypes(typeof(Bike),typeof(Car),typeof(Van))]public class Vehicle{ public ListWheel wheels;}public class Bike: Vehicle{}public class Car: Vehicle{}public class Van: Vehicle{}[BsonKnownTypes(typeof(WheelA),

我有一个类似这样的对象：

[BsonKnownTypes(typeof(Bike),typeof(Car),typeof(Van))]
public class Vehicle
{
    public List<Wheel> wheels;
}

public class Bike: Vehicle
{

}

public class Car: Vehicle
{

}

public class Van: Vehicle
{

}

[BsonKnownTypes(typeof(WheelA),typeof(WheelB))]
public class Wheel
{

}

public class WheelA: Wheel
{
    private int Propa;
}

public class WheelB: Wheel
{
    private int Propb;
}

我有一个名为车辆的集合,并将所有派生对象存储在此集合中.车辆已经为“轮”类型嵌入物体集合.如果我的收藏有不同类型的轮子,那些类型不会被反序列化.有没有办法可以使用嵌入式对象的多态.

解决方法

尝试注册派生类型,如：

BsonClassMap.RegisterClassMap<WheelA>();
BsonClassMap.RegisterClassMap<WheelB>();

或者喜欢：

[BsonDiscriminator(Required = true)]
[BsonKnownTypes(typeof(WheelA),typeof(WheelB))]
public class Wheel

更新：在创建测试项目时,我意识到：您需要使属性公开.
MongoDB无法设置它们,如果它们不可访问.

以下是测试代码：

[TestClass]
public class IntegrationTests
{
    [TestMethod]
    public void Polymorphic_objects_should_deserialize()
    {
        var database = MongoDatabase.Create("connection_string");
        var collection = database.GetCollection("vehicles");

        var car = new Car
        {
            wheels = new List<Wheel>
                       {
                           new WheelA {propA = 123},new WheelB {propB = 456}
                       }
        };
        collection.Insert(car);

        var fetched = collection.AsQueryable<Car>()
                        .SingleOrDefault(x => x.Id == car.Id);

        Assert.IsNotNull(fetched.wheels);
        Assert.AreEqual(2,fetched.wheels.Count);

        Assert.IsInstanceOfType(fetched.wheels[0],typeof(WheelA));
        Assert.IsInstanceOfType(fetched.wheels[1],typeof(WheelB));

        Assert.AreEqual(123,(fetched.wheels[0] as WheelA).propA);
        Assert.AreEqual(456,(fetched.wheels[1] as WheelB).propB);
    }
}

实体与您的列表相同,除了Propa& Propb,被公开.我还向Vehicle添加了一个Id字段,以便能够测试它.测试是绿色的

（编辑：李大同）

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