The problem I'm facing now is I have multiple Orders and each Order contains multiple items. Each Order has to link to a Client and Each item has to link to a Inventory Item. Here's my Order Class

public class Order
    {
        [Key]
        public int Id { get; set; }

        public int TotalItems { get; set; }

        public DateTime DeliveryDate { get; set; }

        public string OrderNumber { get; set; }

        public int ClientId { get; set; }
        [ForeignKey("ClientId")]
        public string DeliveryAddress { get; set; }

        public List<OrderItem> OrderItems { get; set; }
        public Client Clients { get; set; }
}

OrderItem Class

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

        public int OrderId{ get; set; }
        [ForeignKey("OrderId")]

        public int InventoryInfoId { get; set; }
        [ForeignKey("InventoryInfoId")]

        [Required]
        public string ItemCode { get; set; }
        public int Quantity { get; set; }
        public InventoryInfo InventoryInfo { get; set; }
        public Order Order { get; set; }
    }

Any idea of how I can link them?

I think I have solved the above issues

As soon as I process, the next problem pops out.

 @foreach (var item in Model)
    {
    <tr>
        <td>
            @Html.DisplayFor(m => item.OrderNumber)
        </td>
        <td>
            @Html.DisplayFor(m=> item.DeliveryAddress)
        </td>
        <td>
            @Convert.ToDateTime(item.DeliveryDate).ToString("dd-MM-yyyy")
        </td>
        <td>
            @Html.DisplayFor(m=>item.Client.ClientCode)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.TotalItems)
        </td>
        <td>
            <a asp-action="Edit" asp-route-id="@item.Id" >Edit</a> 
            <a asp-controller="OrderItem" asp-action="OrderDetail" asp-route-id="@item.Id" >Details</a> 
            <a asp-action="Delete" asp-route-id="@item.Id" >Delete</a> 

        </td>
    </tr>
    }

This is my Orders Index page, when the details button is been clicked, the page should redirect to OrderItems page. However it doesnot.

@model List<IOSystem.Models.OrderItem>
 @foreach (var item in Model)
    {
        <tr>
            <td>
                @Html.DisplayFor(m => item.ItemCode)
            </td>
            <td>
                @Html.DisplayFor(m => item.Quantity)
            </td>
            <td>
                @Html.ActionLink("Edit", "Edit", new { id = item.Id }) |

                @Html.ActionLink("Delete", "Delete", new { id = item.Id })
            </td>
        </tr>
    }

And here is the error message.

InvalidOperationException: The model item passed into the ViewDataDictionary is of type 'System.Collections.Generic.List1[IOSystem.Models.Order]', but this ViewDataDictionary instance requires a model item of type 'System.Collections.Generic.List1[IOSystem.Models.OrderItem]'.

Forgot to add my controller

[HttpPost, ActionName("OrderDetail")]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> OrderDetailPost(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }
            var orderItems = await _context.Orders.Include(s=>s.OrderItems).FirstOrDefaultAsync(i => i.OrderItemId == id);
            
            return View(orderItems);
        }

CodePudding user response：

Your InvalidOperationException is saying you're passing a List<Order> but the model in your Razor page is a List<OrderItem>

In your controller code:

[HttpPost, ActionName("OrderDetail")]
[ValidateAntiForgeryToken]
public async Task<IActionResult> OrderDetailPost(int? id)
{
    if (id == null)
    {
        return NotFound();
    }
    var orderItems = await _context.Orders.Include(s=>s.OrderItems).FirstOrDefaultAsync(i => i.OrderItemId == id);
    
    return View(orderItems);
}

You're accessing _context.Orders, which is your Orders table. You're .Include-ing the OrderItems but you're returning your Orders.

Either pass back the OrderItems from var orderItems = ... or adjust your Razor page's Model to be a List<Order>.

If you want to select the OrderItems from your Order in the controller code, update your LINQ statement to:

var orderItems = (await _context.Order
    .Include(s => s.OrderItems)
    .FirstOrDefaultAsync(i => i.OrderItemId == id))
    .Select(x => x.OrderItems); // <-- grab just the OrderItems