Inheritance in MongoDb: how to request instances of defined type

Question

This is how I used to utilize inheritance in Entity Framework (POCO):

ctx.Animals // base class instances (all instances)
ctx.Animals.OfType  // inher         


        

Answer 1

Take a look on the documentation http://docs.mongodb.org/ecosystem/tutorial/serialize-documents-with-the-csharp-driver/#scalar-and-hierarchical-discriminators

The main reason you might choose to use hierarchical discriminators is because it makes it possibly to query for all instances of any class in the hierarchy. For example, to read all the Cat documents we can write:

var query = Query.EQ("_t", "Cat");
var cursor = collection.FindAs(query);
foreach (var cat in cursor) {
    // process cat
}