[英]WPF New DataGrid Row Parameter NULL on Button Command
WPF的新功能。 我正在構建的第一個應用程序是使用帶有CommandCommand的RelayCommand和DataGrid編輯或輸入新用戶。 對於具有在打開的行中輸入值的新用戶,按下時將調用OneditButtonCommand,但作為參數傳遞的Item始終為null。 我嘗試在XAML中切換Command和CommandParameter的順序,以查看是否在定義的參數之前設置了Command,但是按鈕命令對象仍然為NULL。 有沒有解決方案跳給任何人? 提前謝謝了!
ViewModel:
public partial class UsersViewModel : INotifyPropertyChanged
{
public RelayCommand<UserViewModel> editButton_Click_Command { get; set; }
public UsersViewModel()
{
editButton_Click_Command = new RelayCommand<UserViewModel>(OneditButton_Click_Command);
this.Users = new ObservableCollection<UserViewModel>();
this.Users.Add(new UserViewModel() { FirstName = "John", LastName = "Doe", EMail = "JohnDoe@yahoo.com", EndDate = new DateTime(2016,2,1), Position = "Developer", UserID = 0 });
}
private ObservableCollection<UserViewModel> _Users;
public ObservableCollection<UserViewModel> Users
{
get { return _Users; }
set { _Users = value; NotifyPropertyChanged("Users"); }
}
private void OneditButton_Click_Command(UserViewModel obj)
{
//Parameter object is always NULL here!!!
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
XAML:
<Window x:Name="Base_V"
x:Class="DbEntities.UsersWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:DbEntities"
xmlns:ViewModels="clr-namespace:DbEntities"
xmlns:staticData="clr-namespace:DbEntities"
mc:Ignorable="d"
Title="UsersWindow" Height="Auto" Width="900">
<Window.Resources>
<staticData:PositionsList x:Key="PositionsList" />
</Window.Resources>
<Window.DataContext>
<ViewModels:UsersViewModel/>
</Window.DataContext>
<Grid>
<FrameworkElement x:Name="dummyElement" Visibility="Collapsed" />
<DataGrid Name="DataGrid1" ItemsSource="{Binding Users}" HorizontalAlignment="Stretch" HorizontalContentAlignment="Stretch"
ColumnWidth="*" AutoGenerateColumns="False">
<DataGrid.Columns>
<DataGridTemplateColumn>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button Command="{Binding DataContext.editButton_Click_Command, ElementName=Base_V}" CommandParameter="{Binding}" >Edit</Button>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTextColumn Header="User ID" Binding="{Binding UserID}" IsReadOnly="True" />
<DataGridTextColumn Header="Last Name" Binding="{Binding LastName}" />
<DataGridTextColumn Header="First Name" Binding="{Binding FirstName}" />
<DataGridTextColumn Header="E-Mail" Binding="{Binding EMail}" />
<DataGridTemplateColumn>
<DataGridTemplateColumn.HeaderTemplate>
<DataTemplate>
<Label Content="Position" />
</DataTemplate>
</DataGridTemplateColumn.HeaderTemplate>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox ItemsSource="{StaticResource PositionsList}" SelectedItem="{Binding Position}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTextColumn Header="End Date" Binding="{Binding EndDate, StringFormat={}{0:MM/dd/yyyy}}" />
</DataGrid.Columns>
</DataGrid>
</Grid>
</Window>
RelayCommand來自此處: http ://www.kellydun.com/wpf-relaycommand-with-parameter/
編輯:建議將UserViewModel發布,以查看是否可以在此處或在其他問題中解決該問題。 還有一些從數據庫中提取的測試用戶。
UserViewModel:
public class UserViewModel : INotifyPropertyChanged
{
private string _FirstName;
public string FirstName
{
get { return _FirstName; }
set { _FirstName = value; NotifyPropertyChanged("FirstName"); }
}
private string _LastName;
public string LastName
{
get { return _LastName; }
set { _LastName = value; NotifyPropertyChanged("LastName"); }
}
private string _EMail;
public string EMail
{
get { return _EMail; }
set { _EMail = value; NotifyPropertyChanged("EMail"); }
}
private int _UserID;
public int UserID
{
get { return _UserID; }
set { _UserID = value; NotifyPropertyChanged("UserID"); }
}
private string _Position;
public string Position
{
get { return _Position; }
set { _Position = value; NotifyPropertyChanged("Position"); }
}
private DateTime? _EndDate;
public DateTime? EndDate
{
get { return _EndDate; }
set { _EndDate = value; NotifyPropertyChanged("EndDate"); }
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
}
在主頁上:
UsersViewModel Usersvm = new UsersViewModel();
Usersvm.Users = new ObservableCollection<UserViewModel>();
DbEntities db = new DbEntities();
var pulledUsers = db.uspGetNonAdminUsers().ToList();
foreach (var result in pulledUsers)
{
var pulledUser = new UserViewModel
{
FirstName = result.FirstName,
LastName = result.LastName,
EMail = result.Email,
UserID = result.UserID,
Position = result.Position,
EndDate = result.EndDate
};
Usersvm.Users.Add(pulledUser);
}
new UsersWindow(Usersvm).Show();
UsersWindow:
public partial class UsersWindow : Window
{
public UsersWindow(UsersViewModel uvm)
{
InitializeComponent();
DataContext = uvm;
}
}
您需要做一些事情:
將您的屬性更新為object
類型:
public RelayCommand<object> editButton_Click_Command { get; set; }
更新您的實例以使用object
editButton_Click_Command = new RelayCommand<object>(OneditButton_Click_Command);
然后,將事件處理程序更新為具有param object
並進行相應的轉換。
private void OneditButton_Click_Command(object obj)
{
var associatedViewModel = obj as UserViewModel;
if (associatedViewModel != null)
{
}
}
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