表中具有可枚举模型的MVC模型

Question

I have a model, and in that model I have 2 enumerable items of another model. Like so:

public class InvoiceModel
{
    public int? InvoiceId { get; set; }
    public IEnumerable<ItemModel> Items { get; set; }
    public IEnumerable<ItemModel> AvailableItems { get; set; )
    public decimal? SubTotal { get; set; }
    public decimal? Discounts { get; set; }
    public decimal? Taxes { get; set; }
    public decimal? Total { get; set; }
}

the ItemModel looks like so:

public class ItemModel
{
    public int? Id { get; set; }
    public decimal? Amount { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public decimal? UnitCost { get; set; }
    public int? Quantity { get; set; }
}

Now in the view, the user is creating an invoice, adding Item models (Items) to the invoice based on AvailableItems in a view that looks like a table.

So we have a table, where each row represent's items added to the invoice. The last row has a drop down list for selection populated by AvailableItems to dynamically add the item they choose from the drop down list to the bottom of the table just before the last row that has the selection for a new item. It also adds the items to the Items property of the model. Except I don't know how to achieve this or where to even start asking.

I have a mock up of what the table is supposed to look like:

Any help would be greatly appreciated!

Answer 1

On the Models side, you're going to need something like this on ItemModel:

 public int? InvoiceId { get; set; }
 public int? AvailableInvoiceId { get; set; }

Or you will have mapping issues since the IEnumerable won't know how to link to ItemModel.

However to be honest I think a few design smells have crept in:

1) A list of AvailableItems is a curious thing to attach to an invoice, are you sure this shouldn't be a separate table/model? The InvoiceId/AvailableInvoiceId really should be required fields, which won't be possible if you try to stuff two things into the same table.

2) Primary keys should not be nullable!

3) I have generally seen navigation properties implemented as ICollection<> rather than IEnumerable<> - you may have issues with this.

Understandable if this is just a mockup of course.