[英]How to filter Bson Document on a computed field of a C# class?
I have several classes that I need to store in a MongoDb collection, these classes have a common base class and common interface defining the common fields. 我有几个需要存储在MongoDb集合中的类,这些类具有公共基类和定义公共字段的公共接口。 Every class have a computed field with the same name but with different implementations.
每个类都有一个具有相同名称但具有不同实现的计算字段。 When I try to query on that field I get the message that the field is not supported
当我尝试查询该字段时,我收到一条消息,提示不支持该字段
I'm running this on a .Net Core 2.2 console application with the latest MongoDb Driver 我正在使用最新的MongoDb驱动程序在.Net Core 2.2控制台应用程序上运行此程序
Interface: 接口:
public interface ITask
{
ObjectId Id { get; set; }
TaskStatus Status { get; set; }
DateTime Timestamp { get; set; }
string UserId { get; set; }
string ComputedField{ get; }
}
Base Class: 基类:
public abstract class BaseTask : ITask
{
[BsonId(IdGenerator = typeof(ObjectIdGenerator))]
public ObjectId Id { get; set; }
[BsonElement("Status")]
public TaskStatus Status { get; set; }
[BsonElement("Timestamp")]
public DateTime Timestamp { get; set; }
[BsonElement("UserId")]
public string UserId { get; set; }
public virtual string ComputedField
{
get { return CalculateMD5Hash(Id.ToString()); }
}
}
Actual class that give me the problem 给我问题的实际课堂
public class MyTask : BaseTask
{
[BsonElement("Field1")]
public Guid Field1{ get; set; }
[BsonElement("ComputedField")]
public override string ComputedField
{
get { return CalculateMD5Hash($"ABC{Field1.ToString()}"); }
}
}
Wrapper that call the MongoDb layer 调用MongoDb层的包装器
public class TaskService<T> : ITaskService<T> where T : ITask
{
private readonly IPersistanceLayer<ObjectId, object> _pl;
public async Task<T> GetNextTask(string key)
{
var oee = _pl.Mongo.Filter<T>(x => x.ConcurrencyKey==key
, typeof(T).Name).OrderBy(x=> x.Timestamp).FirstOrDefault();
return oee;
}
}
MongoDb Layer MongoDb层
public IEnumerable<T> Filter<T>(System.Linq.Expressions.Expression<Func<T, bool>> lambda, string collection)
{
var filter = Builders<T>.Filter.Where(lambda);
return _db.GetCollection<T>(collection).Find(filter).ToList();
}
The error I get is 我得到的错误是
[ERR] {document}.ComputedField is not supported.
In the collection i see the document saved when I insert it but and the value of the computed filed is stored correctly, the only problem is when i try to query on that field 在集合中,当我插入文档时,我看到保存的文档,但是计算字段的值正确存储,唯一的问题是当我尝试查询该字段时
The problem was that I was looking in the wrong collection and casting to the wrong class 问题是我在寻找错误的收藏品并将其投射到错误的类上
public class TaskService<T> : ITaskService<T> where T : ITask
{
private readonly IPersistanceLayer<ObjectId, object> _pl;
public async Task<T> GetNextTask(string key)
{
var nextTask= _pl.Mongo.Filter<T>(x => x.ConcurrencyKey==key
, typeof(T).Name).OrderBy(x=> x.Timestamp).FirstOrDefault();
return nextTask;
}
}
In this method T was of the type BaseTask and not MyTask so my computed field was not there, I have corrected that and now it works 在此方法中,T的类型为BaseTask而不是MyTask,因此我的计算字段不存在,我已对此进行了更正,现在可以正常工作
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