Mongo C＃继承列表

Question

I have a class (a) which inherits a list of (b).

public class a : List<b>
{

}

Now when I try to save an object of this class to Mongo I get an error.

Serializer EnumerableSerializer<b> expected serialization options of type ArraySerializationOptions, not DocumentSerializationOptions.

Have you ever come across anything like this, if anyone could shed some light that would be great. I can't find much in the documentation or online about this.

Answer 1

The top level document being saved to MongoDB cannot be a list, it has to be a class. It also has to have an Id field. So you could do something like this:

public class C
{
    public ObjectId Id { get; set; }
    public A List { get; set; }
}

public class A : List<B>
{
}

Where you have encapsulated the list of type A inside a document (in this case of type C).

However, be careful if you decide to keep your class of type A. If you add custom properties to your class A you will then have to write a custom serializer to ensure that the custom values you added are properly serialized along with the list values. See:

https://jira.mongodb.org/browse/CSHARP-460