ERP_Distribution/Distribution/Models/StockBalance.cs

using System.ComponentModel.DataAnnotations.Schema;

namespace Distribution.Models
{
    public class StockBalance
    {
        public Guid Id { get; set; } = Guid.NewGuid();

        public Guid FK_ItemId { get; set; }
        [ForeignKey("FK_ItemId")]
        public Item Item { get; set; }

        public Guid LocationId { get; set; }
        public LocationType LocationType { get; set; }

        /// <summary>Null for items that don't track batches/expiry — no behavior change for existing items.</summary>
        public Guid? FK_ItemBatchId { get; set; }
        [ForeignKey("FK_ItemBatchId")]
        public ItemBatch? ItemBatch { get; set; }

        /// <summary>Null for items that don't track serial numbers.</summary>
        public Guid? FK_ItemSerialNumberId { get; set; }
        [ForeignKey("FK_ItemSerialNumberId")]
        public ItemSerialNumber? ItemSerialNumber { get; set; }

        public decimal Quantity { get; set; }
        public DateTime UpdatedAt { get; set; } = DateTime.Now;
    }
}