/// <summary>
/// Check if a demand exists for the orderpart, else a new one is created.
/// </summary>
/// <param name="orderPart"></param>
/// <returns></returns>
public IDemandToProvider GetDemand(OrderPart orderPart)
{
var demandOrderParts =
_context.Demands.OfType <DemandOrderPart>().Include(a => a.DemandProvider).Where(a => a.OrderPartId == orderPart.Id).ToList();
IDemandToProvider demand;
if (demandOrderParts.Any())
{
demand = demandOrderParts.First();
}
else
{
demand = _context.CreateDemandOrderPart(orderPart);
_context.SaveChanges();
}
return(demand);
}