如何使用实体框架在WPF c＃中的两个表之间插​​入一对多关系的数据？

Question

try
{
    foreach (IEnumerable<string> row in itemgridshow.Items)
    {
        var valueslist = row.ToList();

        Order_Item oi = new Order_Item();
        oi.Item_Description = valueslist[0].ToString();
        oi.Item_Copy = int.Parse(valueslist[1].ToString());
        oi.Item_Price = int.Parse(valueslist[2].ToString());
        oi.Item_Amount = int.Parse(valueslist[3].ToString());
        oi.Item_Image = valueslist[4].ToString();

        neworder.Order_Item.Add(oi);

        db.Order_Item.Add(oi);
    }

    db.Order_Master.Add(neworder);
    db.SaveChanges();
}

Order_Master is the primary table and Order_Item is the secondary table. I want to insert Order_Master record & many Order_item details in a single save button operation.

db is the context name.

For order_item data is pass through datagrid (itemgrid.items) in string array.

All looks good and above code doesn't cause any errors, but data is not inserted into the database. Please help me to fix this issue.

Answer 1

I don't see any logic issues with the code snippet above.

Try restructuring the code, encapsulating the context usage might uncover why the save isn't happening.

    public void SaveOrder(IEnumerable<string> rows)
    {
        // Create a new order and add items
        var neworder = new Order_Master();
        foreach (var row in rows)
        {
            var valueslist = row.ToList();
            var oi = new Order_Item();

            oi.Item_Description = valueslist[0].ToString();
            // Set more properties...

            // Add the item to the order
            neworder.Order_Item.Add(oi);
        }

        // Instance a context, add the order and save
        try
        {
            using (var db = new OrderContext())
            {
                db.Order_Master.Add(neworder);
                db.SaveChanges();
            }
        }
        catch (Exception e)
        {
            throw new Exception($"Failed to save to database: {e.Message}");
        }
    }

Entity Model should look something like this:

    public class OrderContext : DbContext
    {
        public DbSet<Order_Master> Order_Master { get; set; }
        public DbSet<Order_Item> Order_Items { get; set; }
        // More entities...
    }

    public class Order_Item
    {
        public int Id { get; set; }

        public string Item_Description { get; set; }
        // More properties...
    }

    public class Order_Master
    {
        public Order_Master()
        {
            Order_Item = new List<Order_Item>();
        }

        public ICollection<Order_Item> Order_Item { get; set; }

        public int Id { get; set; }

        public string Order_Description { get; set; }
        // More properties...
    }