在 ICollection<Model> 中绑定附加元素而不破坏 EF EDMX

Question

我无法使用MVVM 方法将数据绑定到DataGrid。可能很傻，但我被困住了。

我有一个 EF6 表 EFTable，看起来像这样

namespace Database.Models
{    
    [Table(Name = "EFTable")]
    public class EFTable
    {
        [Column(IsPrimaryKey = true)]
        [Key]
        public int ID { get; set; }

        public int Col1 { get; set; }

        public int Col2 { get; set; }

        .................
        ...................

    }
}

在我的 ViewModel 中有

 public ICollection<EFTable> EFTableToBindWithDataGrid
 {
     get
     {
         return efTable;
     }
     set
     {
         efTable = value;

         RaisePropertyChanged("EFTableToBindWithDataGrid");
     }
 }

最后在我的 View(xaml) 中我有一个 DataGrid

<DataGrid   ColumnWidth="*"  AutoGenerateColumns="False" ItemsSource="{ Binding Path=EFTableToBindWithDataGrid,Mode=OneWay}" >    
    <DataGrid.Columns>    
        <DataGridTextColumn Header="Col1" Binding="{Binding Col1}"/>
        <DataGridTextColumn Header="Col2" Binding="{Binding Col2}" />
        <!--................-->
         <!--#####HERE-->
        <DataGridTextColumn Header="ColNotInEFTable" Binding="{Binding ColNotInEFTable}" />

    </DataGrid.Columns>   
</DataGrid>

让我说说我的问题

1. 我需要绑定计算值ColNotInEFTable，但它们不在EFTableToBindWithDataGrid中（因为EFTable没有ColNotInEFTable字段）
2. 是否有其他方法可以解决此问题？

提前致谢

Answer 1

从您的Model 创建一个ViewModel。

public class ViewModelInvoiceProduct : INotifyPropertyChanged
{
   //only the properties in Model that you want to show in DataGrid

   //your additional property
   private int _CGST;
   public int CGST
    {
        get
        {
            return _CGST;
        }
        set
        {
            _CGST = value;
            RaisePropertyChanged("CGST");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void RaisePropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

VIEWMODEL：并将AddedInvoiceProductsViewModel 绑定到您的DataGrid

public ICollection<ViewModelInvoiceProduct> AddedInvoiceProductsViewModel {get;set;}

public ICollection<InvoiceProducts> AddedInvoiceProducts
    {
        get
        {
            return invoiceProducts;
        }
        set
        {
            invoiceProducts = value;
            //the idea to populate AddedInvoiceProductsViewModel
            foreach(var invoice in invoiceProducts)
            {
                var temp = new ViewModelInvoiceProduct();
                temp.XXX = invoice.XXX;
                temp.CGST = 1 + 2;
                AddedInvoiceProductsViewModel.Add(temp);
            }
        }
    }

Answer 2

1. 您可以扩展您的 InvoiceProducts 类：将其标记为部分类并将新属性添加到放置到新文件 InvoiceProductsExtended.cs 的部分类中
2. 您还可以将 InvoiceProducts 替换为新类（包装器或继承器）并绑定到它
3. 使用绑定转换器从原始属性计算新值