How to clone an entity in Entity Framework Core?

Question

I'm trying to clone an entity using the SetValues method but I get the following error :

The instance of entity type 'TariffPeriod' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached.

Here is the code :

var period2 = _tariffRepository.GetPeriodFull(period.GUID);
var period3 = new TariffPeriod();
_appDbContext.TariffPeriods.Add(period3);
_appDbContext.Entry(period3).CurrentValues.SetValues(period2);

I see that the error is due to the value of the primary key being copied into the new entity. So, how do I copy the values without the key?

Thanks for your help Eric

Answer 1

You can try getting a clone of the period2 data and modify the Id before assigning to period3

var values = db.Entry(period2).CurrentValues.Clone();
values["Id"] = 0;
db.Entry(period3).CurrentValues.SetValues(values);