CODEWITHSUNDEEP
c#asp.net-mvcmongodb
gonace
gonace

Reputation: 27

MongoDb C# failed to serialize the response

Class (Entity)

public class Entity
{
    public ObjectId Id { get; set; }

    public Entity()
    {
        Id = ObjectId.GenerateNewId();
    }
}

Class (Member)

public class Member : Entity
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Email { get; set; }
    public string MobileNumber { get; set; }
}

Action

public dynamic Get()
{
    var response = UnitOfWork.MemberRepository.GetMembers();

    return response;
}

I'm building a API using .NET WebAPI and using mongodb as a datastore, I'm have some troubles serializing the responding object from the database.

Can't understand why, search the internet a while and found similar problems with no solutions. Either I'm a bad google searcher or there answer is hidden somewhere deep:)

Full stack trace: http://pastie.org/8389787

Upvotes: 0

Views: 366

Answers (1)

mnemosyn
mnemosyn

Reputation: 46311

This is little guessing, but the code really isn't too telling.

I'm pretty sure this is because the C# Mongo driver's BsonDocument exposes a ton of properties like AsBoolean, AsInt, AsString, etc. Calling those getters on data that isn't convertible to the respective type causes an exception. While I don't see them in the stack trace, that might be a compiler optimization.

One solution is to make the code strongly-typed (if it isn't already). I don't know what UnitOfWork.MemberRepository.GetMembers(); is, but it hides what you're doing and it's also not clear what it returns. You're losing a lot of the advantages of the C# driver. The Collection<T> class is pretty much a repository pattern already by the way.

A cleaner approach (they aren't mutually exclusive) is to not serialize the database object to the outside world, but use DTO for the WebAPI side and translate between them, for instance using AutoMapper. I would always do this, because you're throwing an object that might be decorated with DB-Attributes in a serializer you don't know - that could lead to all sorts of problems. Also, you often want to hide certain information from the outside, or make it read-only.

Another option is to use ServiceStack.Text as a JSON-serializer instead, which tends to cause less trouble in my experience.

Upvotes: 1

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