UI未使用更新进行更新 [英] UI not updating with update
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问题描述
我是wpf的新手，我们在wpf上有一个项目，所以我的带领让我学习并做了一些poc和一些我如何用Google搜索并开始学习
当我设计一个mvvm应用程序时
我有列表通过datcontext有源和绑定网格到该源，当我点击更新时我有一个更新按钮我为此更新了更新的代码，但是一旦我关闭了一个drun应用程序，我在UI.please帮助中获得了旧值。
我已经护目镜并找到了一些不同的解决方案。请帮助我发现有点理解。
我的代码我喜欢：
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Hi,
I am new to the wpf and we got one project on wpf so my lead asked me to study and do a poc and some how I googled and started to learn
when I designed a mvvm application
I have list has source and binding grid to that source through datcontext ,I had an update button when I click update I am geeting the updated vale for that ,but once I close an drun the applicaton I am getting the old values In UI.please help.
I have goggled and found some different different solutions.Please help I am finding a bit diificult in understanding.
My code I s like:
view model:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Dataapplication.Model;
using System.Windows.Input;
using System.Windows;
using Dataapplication.View;
using System.ComponentModel;
namespace Dataapplication.ViewModel
{
class ViewModelTest
{
//When the user clicks a button in the View, a command on the ViewModel executes to perform the requested action
private IList<Employee> _UsersList;
private ICommand _mUpdater;//nned to be created while performing any command in view model which is used for defining a command ** here it is for UPDATE**
private ICommand _command;// ** here it is for REMOVE**
public ViewModelTest()
{
_UsersList = new List<Employee>
{
new Employee{EmployeeNumber=1,FirstName="Raj",LastName="hari",Department="Depo",Title="INDIA"},
new Employee{EmployeeNumber=2,FirstName="Mark",LastName="henry",Department="Natural Science",Title="USA"},
new Employee{EmployeeNumber=3,FirstName="Mahesh",LastName="Chand",Department="Physics",Title="USA"},
new Employee{EmployeeNumber=4,FirstName="Vikash",LastName="Nanda",Department="Biology",Title="INDIA"},
new Employee{EmployeeNumber=5,FirstName="Harsh",LastName="Kumar",Department="History", Title="INDIA"},
new Employee{EmployeeNumber=6,FirstName="Reetesh",LastName="Tomar",Department="English", Title="INDIA"},
new Employee{EmployeeNumber=7,FirstName="Deven",LastName="Verma",Department="Physical Educataion", Title="INDIA"},
new Employee{EmployeeNumber=8,FirstName="Ravi",LastName="Taneja",Department="Police", Title="INDIA"}
};
}
//private void Button_Click(object sender, RoutedEventArgs e)
//{
// txtFirstName.GetBindingExpression(TextBox.TextProperty).UpdateSource();
// txtLastName.GetBindingExpression(TextBox.TextProperty).UpdateSource();
// txtPrice.GetBindingExpression(TextBox.TextProperty).UpdateSource();
//}
public IList<Employee> Users
{
get { return _UsersList; }
set { _UsersList = value; }
}
public ICommand UpdateCommand
{
get
{
if (_mUpdater == null)
_mUpdater = new Updater();
return _mUpdater;
}
set
{
_mUpdater = value;
}
}
public ICommand RemoveCommand
{
get
{
if (_command == null)
{
_command = new Remover(CanExecute, Execute);
}
return _command;
}
} //willl be binded to grid
private void Execute(object parameter)
{
int index = Users.IndexOf(parameter as Employee);
if (index > -1 && index < Users.Count)
{
Users.RemoveAt(index);
}
}
private bool CanExecute(object parameter)
{
return true;
}
//**CanExecute and Execute are delegate commands which are used in MVVM to enables the user to hook up UI interactions with code without tightly coupling with two.
//Those two are called ICommand Members
private class Updater : ICommand
{
public bool CanExecute(object parameter)
{
return true;
}
public event EventHandler CanExecuteChanged;
public void Execute(object parameter)
{
}
}
private class Remover : ICommand
{
Predicate<object> canExecute;
Action<object> execute;
public Remover(Predicate<object> _canexecute, Action<object> _execute)
: this()
{
canExecute = _canexecute;
execute = _execute;
}
public Remover()
{
}
public bool CanExecute(object parameter)
{
return canExecute == null ? true : canExecute(parameter);
}
public event EventHandler CanExecuteChanged;
public void Execute(object parameter)
{
execute(parameter);
}
}
}
}
我的观点是：
my view is:
<Window x:Class="Dataapplication.View.testdata1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="DataApplication" Height="300" Width="300" SizeToContent="WidthAndHeight"
ResizeMode="NoResize">
<Grid>
<Grid Margin="0,0,0,20">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<!--<ListView Name="ListViewProducts" Grid.Row="1" Margin="4,109,12,23" ItemsSource="{Binding Path=Products}" SelectedItem="{Binding SelectedProduct}" >-->
<ListView Name="UserGrid" Grid.Row="1" Margin="4,178,12,13" ItemsSource="{Binding Users, Mode=TwoWay}" >
<ListView.View>
<GridView x:Name="grdTest">
<GridViewColumn Header="EmployeeNo" DisplayMemberBinding="{Binding EmployeeNumber}" Width="50" />
<GridViewColumn Header="First Name" DisplayMemberBinding="{Binding FirstName}" Width="80" />
<GridViewColumn Header="Last Name" DisplayMemberBinding="{Binding LastName}" Width="100" />
<GridViewColumn Header="Departments" DisplayMemberBinding="{Binding Department}" Width="80" />
<GridViewColumn Header="Titles" DisplayMemberBinding="{Binding Title}" Width="80" />
</GridView>
</ListView.View>
</ListView>
<!--<TextBox Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="80,7,0,0" Name="txtUserId" VerticalAlignment="Top" Width="178" Text="{Binding ElementName=UserGrid,Path=SelectedItem.UserId}" />-->
<TextBox Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="80,35,0,0" Name="txtFirstName" VerticalAlignment="Top" Width="178" Text="{Binding ElementName=UserGrid,Path=SelectedItem.FirstName}" />
<TextBox Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="80,62,0,0" Name="txtLastName" VerticalAlignment="Top" Width="178" Text="{Binding ElementName=UserGrid,Path=SelectedItem.LastName}" />
<!--<Label Content="UserId" Grid.Row="1" Height="28" Margin="12,12,0,0" Name="label1" VerticalAlignment="Top"/>-->
<Label Content="Last Name" Grid.Row="1" Height="28" HorizontalAlignment="Left" Margin="12,60,0,0" Name="label2" VerticalAlignment="Top" />
<Label Content="First Name" Grid.Row="1" Height="28" HorizontalAlignment="Left" Margin="12,35,0,0" Name="label3" VerticalAlignment="Top" />
<!--update buto added button click-->
<Button Content="Update" Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="310,40,0,0" Name="btnUpdate"
VerticalAlignment="Top" Width="141"
Command="{Binding Path=UpdateCommand}" />
<!--<Button Grid.Row="1" HorizontalAlignment="Left" VerticalAlignment="Top" Width="141" "310,40,0,0" Content="Update" Click="Button_Click" Command="{Binding UpdateCommand}"/-->
<!--Binding ElementName - This is a markup extension which will tell XAML compiler to bind your ListView to Textbox control-->
<TextBox Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="80,117,0,0" x:Name="txtCity" VerticalAlignment="Top" Width="178" Text="{Binding SelectedItem.Department, ElementName=UserGrid}" />
<Label Content="Department" Grid.Row="1" Height="28" HorizontalAlignment="Left" Margin="12,115,0,0" x:Name="label2_Copy" VerticalAlignment="Top" />
<TextBox Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="80,88,0,0" x:Name="txtCountry" VerticalAlignment="Top" Width="178" Text="{Binding SelectedItem.Title, ElementName=UserGrid}" />
<Label Content="Title" Grid.Row="1" Height="28" HorizontalAlignment="Left" Margin="12,86,0,0" x:Name="label2_Copy1" VerticalAlignment="Top" />
<!--<TextBox Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="80,115,0,0" x:Name="txtSTate" VerticalAlignment="Top" Width="178" Text="{Binding SelectedItem.State, ElementName=UserGrid}" />
<Label Content="" Grid.Row="1" Height="28" HorizontalAlignment="Left" Margin="12,113,0,0" x:Name="label2_Copy2" VerticalAlignment="Top" />-->
</Grid>
</Grid>
</Window>
我的模特是：
my model is:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
namespace Dataapplication.Model//model
{ //Model is responsible for exposing data
//model should implement thje INotifyPropertyChanged and/or INotifyCollectionChanged .this is because
//if you are crating a property which needed to update the UI when the value of it is modified, the minimum requirement is to implement the same from INotifyPropertyChanged
//similarly need to implement INotifyCollectionChanged when new item in to collection is to be reflected in UI(view) for example yo are using the listBox, and on click of button
//if we nned to add some daata in to the listbox the UI will know through the INotifyCollectionChanged interface.
public class Employee : INotifyPropertyChanged
{
int _employeeNumber;
string _firstName;
string _lastName;
string _department;
string _title;
private Employee selectedEmployee;
public Employee()
{
_employeeNumber = 0;
_firstName =
_lastName =
_department =
_title = null;
}
public int EmployeeNumber
{
get { return _employeeNumber; }
set
{
_employeeNumber = value;
OnPropertyChanged("EmployeeNumber");
}
}
public string FirstName
{
get { return _firstName; }
set
{
_firstName = value;
OnPropertyChanged("FirstName");
}
}
public string LastName
{
get { return _lastName; }
set
{
_lastName = value;
OnPropertyChanged("LastName");
}
}
public string Department
{
get { return _department; }
set
{
_department = value;
OnPropertyChanged("Department");
}
}
public string Title
{
get { return _title; }
set
{
_title = value;
OnPropertyChanged("Title");
}
}
public Employee SelectedEmployee
{
get { return selectedEmployee; }
set
{
selectedEmployee = value;
OnPropertyChanged("SelectedEmployee");
}
}
public override string ToString()
{
return String.Format("{0} {1} ({2})", FirstName, LastName, EmployeeNumber);
}
#region INotifyPropertyChanged Members
//this is to verify that the property with a given name actually exists on the ViewModel object
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChangedEventArgs args = new PropertyChangedEventArgs(propertyName);//same as PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
this.PropertyChanged(this, args);
}
}
#endregion
}
}
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