Upserting in Mongo DB and the Id problem

Question

I have a problem while upserting to mongo db using the official C# driver.

public abstract class AggregateRoot
{
    /// 

    /// All mongoDb docu         


        

Answer 1

I've encountered similar problem. I wanted to upsert documents using official C# driver. I had a class like this:

public class MyClass
{
    public ObjectId Id { get; set; }
    public int Field1 { get; set; }
    public string Field2 { get; set; }
}

In console I would write: db.collection.update({Field1: 3},{Field1: 3, Field2: "value"}) and it would work. In C# I wrote:

collection.Update(Query.EQ("Field1", 3),
                Update.Replace(new MyClass { Field1 = 3, Field2 = "value" }),
                UpdateFlags.Upsert);

and it didn't work! Because driver includes empty id in update statement and when I upsert second document with different value of Field1 exception E11000 duplicate key error index is thrown (in this case Mongo tries to insert a document with _id that already exists in db).

When I generated _id by myself (like topic starter) I've encountered the same exception (mongo cannot change _id of a document) on upserting objects with existing value of Field1.

Solution is to mark Id property by attribute [BsonIgnoreIfDefault] (and not initialize it). In this case driver omits _id field in update statement and MongoDb generates Id if it necessary.