LiteDB null reference on insert - litedb

Question

I ran into this problem where in I get a null reference exception on insert.
I have two object Models UserInfo and UserConfig. On the first trial, UserConfig references a UserInfo instance
public class UserConfigObject : IUserConfig
{
BsonRef("userInfo")]
public IUserInfo UserInfo { get; set; }
public string AssignedJob { get; set; }
public string[] QueueItems { get; set; }
}
public class UserInfoObject : IUserInfo
{
[BsonId]
public int ID { get; set; }
public string Name { get; set; }
public string Username { get; set; }
public string IPAddress { get; set; }
}
And a method to insert the data into the database
public void AddUser(IUserConfig user)
{
var uconCollection = DatabaseInstance.GetCollection<IUserConfig>("userConfig");
var uinCollection = DatabaseInstance.GetCollection<IUserInfo>("userInfo");
uinCollection.Insert(user.UserInfo);
uconCollection.Insert(user);
}
This set up works fine but when I try to change the reference to UserInfo references UserConfig
public class UserInfoObject : IUserInfo
{
[BsonId]
public int ID { get; set; }
public string Name { get; set; }
public string Username { get; set; }
public string IPAddress { get; set; }
[BsonRef("userConfig")]
public IUserConfig UserConfig { get; set; }
}
public class UserConfigObject : IUserConfig
{
[BsonRef("userInfo")]
public IUserInfo UserInfo { get; set; }
[BsonId(true)]
public int ConfigID { get; set; }
public string AssignedJob { get; set; }
public string[] QueueItems { get; set; }
}
With a method call for
public void AddUser(IUserInfo user)
{
var uconCollection = DatabaseInstance.GetCollection<IUserConfig>("userConfig");
var uinCollection = DatabaseInstance.GetCollection<IUserInfo>("userInfo");
uconCollection.Insert(user.UserConfig);
uinCollection.Insert(user);
}
It no longer works, it throws an System.NullReferenceException: 'Object reference not set to an instance of an object.' on uinCollection.Insert(user);
Either v3 or v4, it doesn't work with the latter set up

Answer 1

Had the same problem but with collections. I've tried to save collection of invitations like so:
using var db = new LiteRepository(_connectionString);
var invitations = new List<Invitation>
{
// populate list
};
db.Insert(invitations);
The problem is that T parameter resolved as IEnumerable<Invitation> not just Invitation, so if you are inserting a collection, set type explicitly.
db.Insert<Invitation>(invitations);