DDS not saving entity when specifying id

Question

When specifying a given id to an entity before persisting it using a dynamic data store in episerver, the entity is not persisted. According to tutorials I have seen this should have been just fine. Any clues? No exceptions are thrown, and the Save call returns the Id of the entity I specified the id of.

var winnerEntity = new DailyXMasLotteryWinner
{
    Id = Identity.NewIdentity(guid),
    FullName = fullName,
    Email = email,
    Phone = phone,
    WinnerTime = DateTime.Now
}

winnerStore.Save(winnerEntity); // does not persist to database!
winnerStore.Items().Count() == 0;
winnerEntity.Id = null;
winnerStore.Save(winnerEntity); // persists to database just fine!
winnerStore.Items().Count() == 1;

Answer 1

I'm not aware of your patterns but this is how I typically implement DDS

using System;
using System.Linq;
using EPiServer.Data;
using EPiServer.Data.Dynamic;
using EPiServer.ServiceLocation;

namespace Herlitz.EPiBlog.Models.DDS
{

    public interface IDailyXMasLotteryWinner
    {
        DailyXMasLotteryWinner Create(string fullName);

        DailyXMasLotteryWinner Get(string fullName);

        bool Exist(string property, string value);
    }

    [ServiceConfiguration(typeof(IDailyXMasLotteryWinner))]
    public class DailyXMasLotteryWinner : IDailyXMasLotteryWinner //,IDynamicData
    {
        private readonly DynamicDataStore _store = DynamicDataStoreFactory.Instance.CreateStore(typeof(DailyXMasLotteryWinner));

        public Identity Id { get; set; }

        public string FullName { get; set; }

        public DailyXMasLotteryWinner Create(string fullName)
        {
            if (Exist(property: "FullName", value: fullName))
            {
                return Get(fullName: fullName);
            }

            Id = Identity.NewIdentity(Guid.NewGuid());
            FullName = fullName;

            _store.Save(this);
            return this;
        }

        public DailyXMasLotteryWinner Get(string fullName)
        {
            return _store.Find<DailyXMasLotteryWinner>(propertyName: "FullName", value: fullName).FirstOrDefault();
        }

        public bool Exist(string property, string value)
        {
            return _store.Find<DailyXMasLotteryWinner>(propertyName: property, value: value).Any();
        }
    }
}

Tested with this

@{

    var xmasLocator = ServiceLocator.Current.GetInstance<IDailyXMasLotteryWinner>();
    var winner = xmasLocator.Create(fullName: "Ned Flanders");

    <div>@winner.Id @winner.FullName</div>
}

And it works

Obviously you should adapt this to your patterns, if it doesn't work it would probably be your database user that has insufficient rights.