2

我有一个带有分离的 BsonClass 映射的 C# 类层次结构。我所有的课程都使用自定义顺序 int id 生成。Last Id 存储在名为“Counter”的特殊集合中。我的问题是当像 InsertOneAsync 这样的 mongo 集合方法被调用时 InvalidCastException 被抛出。

基础实体类：

[Serializable]
public abstract class Entity<TIdentifier> : IEntity<TIdentifier>
{
    public TIdentifier Id { get; set; }

    public DateTime CreatedDate { get; set; }

    public DateTime UpdatedDate { get; set; }

    public virtual bool IsTransient()
    {
        return (object) this.Id == null || this.Id.Equals((object) default (TIdentifier));
    }
}

儿童班：

public class Child : Entity<int> 
{
    public int SomeData { get; set; }
}

基类图：

public class EntityMap
{
    public static void Register()
    {
        BsonClassMap.RegisterClassMap<Entity<int>>(cm =>
        {
            cm.AutoMap();
            cm.MapIdProperty(c => c.Id)
                .SetIdGenerator(SeqIntIdGenerator<Entity<int>>.Instance)
                .SetSerializer(new Int32Serializer(BsonType.Int32));
        });
    }
}

子类图：

public class ChildMap
{
    public static void Register()
    {
        BsonClassMap.RegisterClassMap<Child>(cm =>
        {
            cm.AutoMap();
            cm.SetIgnoreExtraElements(true);
        });
    }
}

顺序 int id 生成器类：

public class SeqIntIdGenerator<TEntity> : IIdGenerator
{
    public static SeqIntIdGenerator<TEntity> Instance { get; } = new SeqIntIdGenerator<TEntity>();

    public object GenerateId(object container, object document)
    {
        //InvalidCastException thrown here on InsertOneAsync!!!
        var idSequenceCollection = ((IMongoCollection<TEntity>)container).Database.GetCollection<dynamic>("Counters");

        var filter = Builders<dynamic>.Filter.Eq("_id", ((IMongoCollection<TEntity>)container).CollectionNamespace.CollectionName);
        var update = Builders<dynamic>.Update.Inc("Seq", 1);

        var options = new FindOneAndUpdateOptions<dynamic>
        {
            IsUpsert = true,
            ReturnDocument = ReturnDocument.After
        };

        return idSequenceCollection.FindOneAndUpdate(filter, update, options).Seq;
    }

    public bool IsEmpty(object id)
    {
        return (int)id == 0;
    }
}

将容器从 Object 转换为 IMongoCollection> 时引发 InvalidCastException。怎么做才对？我的 C# 驱动程序版本是 2.7.2。

4

2 回答 2

1

如果您已经在使用动态，则可以切换出反射代码>

public object GenerateId(object container, object document)
{
    var containerDynamic = (dynamic) container;
    var idSequenceCollection = containerDynamic.Database.GetCollection<dynamic>("Counters");

    var filter = Builders<dynamic>.Filter.Eq("_id", containerDynamic.CollectionNamespace.CollectionName);
    var update = Builders<dynamic>.Update.Inc("Seq", 1);

    var options = new FindOneAndUpdateOptions<dynamic>
    {
        IsUpsert = true,
        ReturnDocument = ReturnDocument.After
    };

    return idSequenceCollection.FindOneAndUpdate(filter, update, options).Seq;
}
于 2019-01-30T15:42:01.357 回答
0

Ok, here is my ugly solution using reflection

public class SeqIntIdGenerator<TEntity> : IIdGenerator
{
    var containerType = container.GetType();
    var database = (IMongoDatabase)containerType.GetProperty("Database").GetValue(container);
    var collectionNamespace = (CollectionNamespace)containerType.GetProperty("CollectionNamespace").GetValue(container);

    var idSequenceCollection = database.GetCollection<dynamic>("Counters");

    var filter = Builders<dynamic>.Filter.Eq("_id", collectionNamespace.CollectionName);
    var update = Builders<dynamic>.Update.Inc("Seq", 1);

    var options = new FindOneAndUpdateOptions<dynamic>
    {
        IsUpsert = true,
        ReturnDocument = ReturnDocument.After
    };

    return idSequenceCollection.FindOneAndUpdate(filter, update, options).Seq;
    }

    public bool IsEmpty(object id)
    {
        return (int)id == 0;
    }
}
于 2019-01-29T10:31:32.977 回答