Polymorphism problem in MongoDb with NoRM driver

Question

I have classes

[MongoDiscriminated] public abstract class Content { public int? Id { get; set; } public int? ParentId { get; set; } public string Slug { get; set; } public string Path { get; set; } public string Title { get; set; } } public class Area : Content { }

Query like this works

var item = mongo.GetCollection<Area>().AsQueryable().FirstOrDefault();

But when I make a query like

var item = mongo.GetCollection<Content>().AsQueryable().FirstOrDefault();

I get an InvalidCastException

Object must implement IConvertible.

What's wrong? It shouldn't be a problem to convert Area to Content. Do I really have to make Content to implement IConvertible?

Chris Shain · Accepted Answer · 2011-05-10 04:02:10Z

0

You could just cast it after the query:

mongo.GetCollection<Area>().AsQueryable().Cast<Content>().FirstOrDefault()

answered May 10, 2011 at 4:02

Chris Shain

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Comments

Zaid Masud · Accepted Answer · 2011-08-30 18:51:08Z

Just submitted a pull request on github to fix this exception:

https://github.com/atheken/NoRM/pulls

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