Enum can't be deserialized when using Linq

问题:

So I have this enum

public enum JobStatus
{
    Created = 0,
    Assigning = 1,
    Assigned = 2,
    Started = 3,
    Finished = 4
}

In this interface

public interface IJob
{
    Guid Id { get; set; }
    JobStatus Status { get; set; }
    bool IsFaulted { get; set; }
    string ErrorMessage { get; set; }
}

I plop one of these guys in the database, and it goes fine. This is what that looks like.

{ "_id" : { "$uuid" : "4e5002b6-3c80-b497-4a33-46b0ea5a39bf"} 
, "_t" : "MyJobObject" 
, "Status" : 0 
, "IsFaulted" : false 
, "ErrorMessage" :  null  
, "Location" : "overthere"}

Then when I try and grab one with this code

Database.GetCollection<IJob>("Jobs").AsQueryable().FirstOrDefault(x=>x.Status == JobStatus.Created);

That throws an exception

Unable to determine the serialization information for the expression: jobs.Status.
   at MongoDB.Driver.Linq.Utils.BsonSerializationInfoFinder.GetSerializationInfo(Expression node, Dictionary`2 serializationInfoCache)
   at MongoDB.Driver.Linq.Utils.BsonSerializationInfoHelper.GetSerializationInfo(Expression node)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildComparisonQuery(Expression variableExpression, ExpressionType operatorType, ConstantExpression constantExpression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildComparisonQuery(BinaryExpression binaryExpression)
   at MongoDB.Driver.Linq.PredicateTranslator.BuildQuery(Expression expression)
   at MongoDB.Driver.Linq.SelectQuery.BuildQuery()
   at MongoDB.Driver.Linq.SelectQuery.Execute()
   at MongoDB.Driver.Linq.MongoQueryProvider.Execute(Expression expression)
   at MongoDB.Driver.Linq.MongoQueryProvider.Execute[TResult](Expression expression)
   at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source)

My first go I didn't have the enums assigned to integers, and that produced the same result. I'm seeing this on two different machines, and two fresh installs of MongoDb, one on windows and one on Ubuntu 12.04.

Not sure what to do about this, any ideas?

回答1:

I ended up doing

Database.GetCollection<IJob>("Jobs").AsQueryable().ToEnumerable().FirstOrDefault(x=>x.Status == JobStatus.Created);

and it works fine, though I'm a little worried that it may be pulling all the data down at that point. It doesn't appear any slower though, and I had >50k records at one point, and you'd think that you'd see a performance degradation if that's what was happening.