void replaceListInDB <T>(ICollection <T> listToInsert, ICollection <T> listToReplace, IEqualityComparer <T> comparer)
{
var substraction = listToReplace.Except(listToInsert, comparer).ToList();
foreach (var i in substraction)
{
_context.Remove(i);
}
foreach (var i in listToInsert)
{
/*try
* {*/
_context.Add(i);
/*}
* catch (InvalidOperationException e)
* {
* _context.Update(i);
* }*/
}
}