Question

I’m trying to build a generic method to handle all my partial updates via MongoDB C# driver, using the following method:

public bool UpdateObject<T>(UpdatableObject<T> updatableObject)
    where T : new()
{
    var builder = GenerateMongoUpdateBuilder(updatableObject.ModifiedFields);
    var collection = GetCollection<T>();
    var result = collection.Update(Query.EQ("_id", BsonValue.Create(updatableObject.Id)), builder, new MongoUpdateOptions { Flags = UpdateFlags.Multi });
    return result.UpdatedExisting;
}

private static UpdateBuilder GenerateMongoUpdateBuilder(Dictionary<string, object> modifiedFields)
{
    var builder = new UpdateBuilder();
    foreach (var modifiedField in modifiedFields)
    {
        var type = modifiedField.Value.GetType();
        if (type.IsPrimitive || type.IsValueType || (type == typeof(string)))
        {
            builder.Set(modifiedField.Key, BsonValue.Create(modifiedField.Value));
        }
        else
        {
            builder.Set(modifiedField.Key, modifiedField.Value.ToBsonDocument());
        }
    }
    return builder;
}

I had to struggle for a while until I found the solution to handle primitive types via BsonValue and non-primitive types via BsonDocument. Everything worked well, until…We’ve created an object which holds a dictionary. The insert works perfectly, but once it goes into update (using this method) – it cannot be deserialized any more. Looking at the object in the Mongo before and after the update indicates that it’s not the same object anymore – after the update it has additional _t field holds “System.Collections.Generic.Dictionary`2[System.String,[SomeObject, SomeObjectAssembly]]”

So I’m starting to question my implementation…

Any idea what am I doing wrong?

Thanks,
Nir.

Answer 1

With the courtesy of Robert Stam, the issue was resolved. It’s all described in the Jira item.
Thank you!