RavenDB and Composite pattern

Question

Let say I have such structure

public class Form
{
   public List<Field> Fields { get; set; }
}

The Field class can be composite and include other Fields derived from the Field class as well, so I have some sort of hierarchical structure. The Form is persisted into RavenDB as solid document and it works ok. I am just wondering about getting Form instance back from RavenDB, I want Raven to create appropriate classes (classes, which are derived from Field class). So let's say if I have two derived classes FieldDerived1 and FieldDerived2 and put them into the Fields collection of the Form after getting them back I want have two elements with actual types - FieldDerived1 and FieldDerived2 with all additional properties I added to these classes?

Answer 1

It will work just fine. Raven uses Json.Net for it's serialization, which will add a $type property to your data so it can be properly deserialized to the correct type.

Assuming your fields look something like this:

public class Field
{
  public string Name {get; set;}
}

public class FieldDerived1 : Field
{
  public int Length {get; set;}
}

public class FieldDerived2 : Field
{
  public string Color {get; set;}
}

Raven will store the Form class like this:

{
  Fields: [
    {
      "$type": "YourNamespace.FieldDerived1, YourAssembly",
      "Name": "foo",
      "Length": 10
    },
    {
      "$type": "YourNamespace.FieldDerived2, YourAssembly",
      "Name": "bar",
      "Color": "blue"
    }
  ]
}