Question

我有一个MainWindow包含DataGrid，还有一个Button Edit，

<DataGrid x:Name="EmpDataGrid"
                  Grid.Row="1"
                  AutoGenerateColumns="False"                     
                  ItemsSource="{Binding loadDataBinding,Mode=TwoWay}"

    SelectedItem="{Binding CurrentCustomer}" Grid.ColumnSpan="2">

<DataGrid.Columns>

                <DataGridTextColumn Header="CustmorID" Binding="{Binding ID}" />
                <DataGridTextColumn Header="CustmorNom" Binding="{Binding nom}" />
                <DataGridTextColumn Header="CustmorPrenom" Binding="{Binding prenom}" />
                <DataGridTextColumn Header="CustmorReference" Binding="{Binding reference}" />
            </DataGrid.Columns>

 <Button 
            Content="Edit"                
           Command="{Binding Edit}"
           CommandParameter="{Binding CurrentCustomer}" />

然后我调用Window Update，XAML Window Update：

  <Button Command="{Binding UpdateCustomer}" 
  <TextBox x:Name="nom" Text="{Binding CustomerToAddObject.nom,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" />        
    <TextBox x:Name="prenom" Text="{Binding CustomerToAddObject.prenom,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" ></TextBox>        
    <TextBox x:Name="reference" Text="{Binding CustomerToAddObject.reference,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" ></TextBox>

我的ViewModel：

class ViewModel1 : ViewModelBase
{        
    Test1Entities context = new Test1Entities();     
  public ViewModel1()
    { using (Test1Entities context = new Test1Entities())
        {
            _loadDataBinding = new ObservableCollection<Custmor>(context.Custmor.ToList());
        }
        edit = new RelayCommand(start);           
        CustomerToAddObject = new Custmor();                
        updateCustomer = new RelayCommand(UpdateFunction);              
    }

     private ICommand edit;
      public ICommand Edit
    {
        get
        {
            return edit;
        }
    }
    //To call Update Window: 
    private void start(object obj)
    {  
         Update windowUpdate = new Update();       
         windowUpdate.Show();
     }  

     private ICommand updateCustomer;
    public ICommand UpdateCustomer
    {
        get { return updateCustomer; }
    }            

    private void UpdateFunction(object obj)
    {
        MessageBox.Show(currentCustomer.nom);
        MessageBox.Show(customerToAddObject.nom);
        using (Test1Entities context = new Test1Entities())
        {
            Custmor cus = context.Custmor.Find(currentCustomer.ID);
            cus.nom = customerToAddObject.nom;
            cus.prenom = customerToAddObject.prenom;
            cus.reference = customerToAddObject.reference;

            context.SaveChanges();
        }
    }


     // customerToAddObject
    private Custmor customerToAddObject;
    public Custmor CustomerToAddObject
    {
        get { return customerToAddObject; }
        set { customerToAddObject = value; }
    }


    //CurrentCustomer  
    private Custmor currentCustomer;
    public Custmor CurrentCustomer
    {
    get { return currentCustomer; }
        set
        {   currentCustomer = value;
            OnPropertyChanged("CurrentCustomer");
        }  
}

当我执行时，我有这个错误：

这是我的应用程序的首次执行，从我的数据库显示是正确的：

感谢您的帮助，

Answer 1

尝试将DataContext窗口的Update设置为ViewModel1的同一个实例：

private void start(object obj)
{
    Update windowUpdate = new Update();
    windowUpdate.DataContext = this; //<--
    windowUpdate.Show();
}

如果您要创建新实例，则显然需要初始化此实例的CurrentCustomer属性。

在datagrid xaml MVVM中更新时出错

1 个答案: