INotifyPropertyChanged 没有刷新我在 WPF MVVM 实体中的列表视图
INotifyPropertyChanged is not refreshing my listview in WPF MVVM entity
我在我的视图模型中有一个操作可以将记录添加到实体框架work.I有一个操作可以在视图中显示记录，如下所示：
private void FillProspects()
{
var q = (from a in ctx2.Prospects// 'ctx' is the object of entity
select a).ToList();
this.Prospects = q; // 'Porspects' is a collection of entity class this I have bound with my List view in my view
}
这将在构建我的视图时调用 model.as 结果是我视图中的列表视图将显示记录。
我在我的视图模型中有一个添加记录操作。我在我的视图模型中创建了对应于实体 class 中生成的属性的属性，例如：
private String _FirstName;
public String FirstName
{
get
{
return _FirstName;
}
set
{
_FirstName = value;
}
}
我在视图模型中的添加记录操作是：
public void Add1()
{
newprospect = new Prospect();
newprospect.ID = Guid.NewGuid();
newprospect.FirstName = FirstName;
newprospect.LastName = LastName;
newprospect.Address = Address;
newprospect.State = State;
newprospect.City = City;
newprospect.ZIP = ZIP;
prospect = newprospect;
ctx2.AddToProspects(prospect);
FillProspects();
//RaisePropertyChanged("Prospects");
}
我继承了 : INotifyPropertyChanged 并导入了
using System.Windows.Input;
public event PropertyChangedEventHandler PropertyChanged = delegate { };
private void RaisePropertyChanged(string property) { PropertyChanged(this, new PropertyChangedEventArgs(property)); }
但是我的通知在添加记录后没有刷新我的视图 Listview 记录。所以我只是在 addrecord 操作中调用填充记录方法 'FillProspects'。这是执行 MVVM 的正确方法吗？为什么我的 Listview 在我丢失的地方添加记录操作后没有得到刷新？我试过
RaisePropertyChanged("Prospects");在添加记录操作中...但它没有刷新。所以我再次调用填充方法操作
我的完整视图模型：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
using System.Windows.Input;
using System.Collections.ObjectModel;
namespace Wpfentity3
{
public class frmProspects_VM : INotifyPropertyChanged
{
TestsEntities ctx2 = new TestsEntities();
public ObservableCollection<Prospect> prospects { get; set; }
//This is the collection where records - er, entities - returned by a query are stored;
//Prospect is the generated class that defines a record - er,
//an entity as well as the query for that table.
private CommandMap _Commands;
public CommandMap Commands { get { return _Commands; } }
Prospect newprospect;
//This holds a new prospect that is created and then added to the prospects collection
private Prospect _prospect;
public Prospect prospect {
get
{
return _prospect;
}
set
{
_prospect = value;
RaisePropertyChanged("prospect");
}
}
//prospect is the object that holds the current record from the Prospects table.
//MainWindow controls are bound to this object
public frmProspects_VM()
{
//FillProspects();
ctx2 = new TestsEntities();
//This instantiates the EntityManager class ;
prospects = new ObservableCollection<Prospect>();
//This instantiates the prospects collection of Prospect records - er, entities;
_Commands = new CommandMap();
_Commands.AddCommand("Add", x => Add1());
}
private ObservableCollection<Prospect> _prospects;
public ObservableCollection<Prospect> Prospects
{
get
{
return _prospects;
}
set
{
_prospects = value;
RaisePropertyChanged("Prospects");
}
}
private String _FirstName;
public String FirstName
{
get
{
return _FirstName;
}
set
{
_FirstName = value;
}
}
private String _LastName;
public String LastName
{
get
{
return _LastName;
}
set
{
_LastName = value;
}
}
private String _Address;
public String Address
{
get
{
return _Address;
}
set
{
_Address = value;
}
}
private String _State;
public String State
{
get
{
return _State;
}
set
{
_State = value;
}
}
private String _City;
public String City
{
get
{
return _City;
}
set
{
_City = value;
}
}
private String _ZIP;
public String ZIP
{
get
{
return _ZIP;
}
set
{
_ZIP = value;
}
}
public void Add1()
{
newprospect = new Prospect();
newprospect.ID = Guid.NewGuid();
newprospect.FirstName = FirstName;
newprospect.LastName = LastName;
newprospect.Address = Address;
newprospect.State = State;
newprospect.City = City;
newprospect.ZIP = ZIP;
prospect = newprospect;
ctx2.AddToProspects(prospect);
Prospects.Add(newprospect);
}
public event PropertyChangedEventHandler PropertyChanged = delegate { };
private void RaisePropertyChanged(string property) { PropertyChanged(this, new PropertyChangedEventArgs(property)); }
}
}
我的看法 xamal:
<Window x:Class="Wpfentity3.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
WindowStartupLocation="CenterScreen"
Title="Prospects"
Height="482" Width="500" MaxWidth="500" MaxHeight="600"
xmlns:cusns="clr-namespace:Wpfentity3">
<StackPanel Height="290" VerticalAlignment="Top">
<StackPanel Orientation="Horizontal" >
<Label
Content="Prospects"
BorderBrush="Blue" BorderThickness="1"
HorizontalAlignment="Left" VerticalAlignment="Top"
FontSize="24" FontFamily="Comic Sans MS"
Padding="13,3,13,9" Margin="5"
Foreground="Purple" Background="LemonChiffon" />
<Label
Content="{Binding Path=label}" Foreground="Red" FontSize="14"
HorizontalAlignment="Right" VerticalAlignment="Center"
Height="auto" Margin="180,0,10,0" />
</StackPanel>
<Grid
HorizontalAlignment="Left" VerticalAlignment="Top"
Height="120" Width="475" >
<Grid.RowDefinitions>
<RowDefinition Height="25*" />
<RowDefinition Height="25*" />
<RowDefinition Height="25*" />
<RowDefinition Height="25*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="90*" />
<ColumnDefinition Width="135*" />
<ColumnDefinition Width="45*" />
<ColumnDefinition Width="32*" />
<ColumnDefinition Width="57*" />
<ColumnDefinition Width="118*" />
</Grid.ColumnDefinitions>
<Label
Content="First name"
Grid.Row="0" Grid.Column="0" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtFirstName"
Grid.Column="1"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding Path=FirstName}"
Width="130" />
<Label
Content="Last name"
Grid.Row="1" Grid.Column="0" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtLastName"
Grid.Row="1" Grid.Column="1"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding LastName}"
Width="130" />
<Label
Content="Address"
Grid.Row="2" Grid.Column="0" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtAddress"
Grid.Row="2" Grid.Column="1"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding Address}"
Width="300" Grid.ColumnSpan="5" />
<Label
Content="City"
Grid.Row="3" Grid.Column="0" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtCity"
Grid.Row="3" Grid.Column="1"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding City}"
Width="130" />
<Label
Content="State"
Grid.Row="3" Grid.Column="2" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtState"
Grid.Row="3" Grid.Column="3" Width="30" MaxLength="2" CharacterCasing="Upper" Text="{Binding State}"
HorizontalAlignment="Left" VerticalAlignment="Center" />
<Label
Content="ZIP code"
Grid.Row="3" Grid.Column="4" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtZIP"
Grid.Row="3" Grid.Column="5" MaxLength="10"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding ZIP}"
Width="90" />
</Grid>
<StackPanel Orientation="Horizontal" Margin="0,10,0,0">
<Button Name="btnFind"
Content="_Find"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnAdd"
Content="_Add" Command="{Binding Commands.Add}"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnEdit"
Content="_Edit"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnDelete"
Content="_Delete"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnSave"
Content="_Save"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnCancel"
Content="_Cancel"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnClose"
Content="Cl_ose"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0"
/>
</StackPanel>
<StackPanel Height="34" Margin="10">
<Grid Margin="10">
<ListView Name="lvprospects" ItemsSource="{Binding Prospects}" Margin="0,0,0,-200">
<ListView.View>
<GridView>
<GridViewColumn Header="FirstName" Width="120" DisplayMemberBinding="{Binding FirstName}" />
<GridViewColumn Header="LastName" Width="50" DisplayMemberBinding="{Binding LastName}" />
<GridViewColumn Header="Address" Width="50" DisplayMemberBinding="{Binding Address}" />
<GridViewColumn Header="City" Width="50" DisplayMemberBinding="{Binding City}" />
<GridViewColumn Header="State" Width="50" DisplayMemberBinding="{Binding State}" />
<GridViewColumn Header="ZIP" Width="50" DisplayMemberBinding="{Binding ZIP}" />
</GridView>
</ListView.View>
</ListView>
</Grid>
</StackPanel>
</StackPanel>
如果您要将视图绑定到 ViewModel 中的集合，我建议使用 ObservableCollection。
ObservableCollection 实现了 INotifyCollectionChanged，它会在添加或删除元素时通知视图。
有了这个，您就不需要 "FillProspects" 方法和 "RaisePropertyChanged("Prospects")".
如果您想了解更多信息，我建议您发布如何绑定 XAML 以及如何构建 "Prospects" 对象（我们甚至不知道它是什么类型，我只是假设它不是ObservableCollection).
编辑：
您将 ListView 绑定到 "Prospects"，但在您的 ViewModel 中，我看到 "Prospects" 是 "List" 类型，它需要是 "ObservableCollection"。我看到您有一个名为 "prospects" 的 ObservableCollection，但您没有在任何地方使用它。这可能是问题所在吗？
可以将新项目添加到数据库，然后使用相同的刷新方法再次检索集合FillProspects：
你做的基本上是正确的。
将 Prospects 属性 的类型从 List<Prospect> 更改为 ObservableCollection<Prospect>:
private ObservableCollection<Prospect> _prospects = new ObservableCollection<Prospect>();
public ObservableCollection<Prospect> Prospects
{
get
{
return _prospects;
}
set
{
_prospects = value;
RaisePropertyChanged("Prospects");
}
}
并在您的 Add1 方法中将新的 Prospect 对象添加到该集合中：
public void Add1()
{
newprospect = new Prospect();
newprospect.ID = Guid.NewGuid();
newprospect.FirstName = FirstName;
newprospect.LastName = LastName;
newprospect.Address = Address;
newprospect.State = State;
newprospect.City = City;
newprospect.ZIP = ZIP;
prospect = newprospect;
ctx2.AddToProspects(prospect);
Prospects.Add(newprospect);
}
仅将其添加到 DbContext 不会影响 ListView。
我在我的视图模型中有一个操作可以将记录添加到实体框架work.I有一个操作可以在视图中显示记录，如下所示：
private void FillProspects()
{
var q = (from a in ctx2.Prospects// 'ctx' is the object of entity
select a).ToList();
this.Prospects = q; // 'Porspects' is a collection of entity class this I have bound with my List view in my view
}
这将在构建我的视图时调用 model.as 结果是我视图中的列表视图将显示记录。 我在我的视图模型中有一个添加记录操作。我在我的视图模型中创建了对应于实体 class 中生成的属性的属性，例如：
private String _FirstName;
public String FirstName
{
get
{
return _FirstName;
}
set
{
_FirstName = value;
}
}
我在视图模型中的添加记录操作是：
public void Add1()
{
newprospect = new Prospect();
newprospect.ID = Guid.NewGuid();
newprospect.FirstName = FirstName;
newprospect.LastName = LastName;
newprospect.Address = Address;
newprospect.State = State;
newprospect.City = City;
newprospect.ZIP = ZIP;
prospect = newprospect;
ctx2.AddToProspects(prospect);
FillProspects();
//RaisePropertyChanged("Prospects");
}
我继承了 : INotifyPropertyChanged 并导入了
using System.Windows.Input;
public event PropertyChangedEventHandler PropertyChanged = delegate { };
private void RaisePropertyChanged(string property) { PropertyChanged(this, new PropertyChangedEventArgs(property)); }
但是我的通知在添加记录后没有刷新我的视图 Listview 记录。所以我只是在 addrecord 操作中调用填充记录方法 'FillProspects'。这是执行 MVVM 的正确方法吗？为什么我的 Listview 在我丢失的地方添加记录操作后没有得到刷新？我试过
RaisePropertyChanged("Prospects");在添加记录操作中...但它没有刷新。所以我再次调用填充方法操作
我的完整视图模型：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;
using System.Windows.Input;
using System.Collections.ObjectModel;
namespace Wpfentity3
{
public class frmProspects_VM : INotifyPropertyChanged
{
TestsEntities ctx2 = new TestsEntities();
public ObservableCollection<Prospect> prospects { get; set; }
//This is the collection where records - er, entities - returned by a query are stored;
//Prospect is the generated class that defines a record - er,
//an entity as well as the query for that table.
private CommandMap _Commands;
public CommandMap Commands { get { return _Commands; } }
Prospect newprospect;
//This holds a new prospect that is created and then added to the prospects collection
private Prospect _prospect;
public Prospect prospect {
get
{
return _prospect;
}
set
{
_prospect = value;
RaisePropertyChanged("prospect");
}
}
//prospect is the object that holds the current record from the Prospects table.
//MainWindow controls are bound to this object
public frmProspects_VM()
{
//FillProspects();
ctx2 = new TestsEntities();
//This instantiates the EntityManager class ;
prospects = new ObservableCollection<Prospect>();
//This instantiates the prospects collection of Prospect records - er, entities;
_Commands = new CommandMap();
_Commands.AddCommand("Add", x => Add1());
}
private ObservableCollection<Prospect> _prospects;
public ObservableCollection<Prospect> Prospects
{
get
{
return _prospects;
}
set
{
_prospects = value;
RaisePropertyChanged("Prospects");
}
}
private String _FirstName;
public String FirstName
{
get
{
return _FirstName;
}
set
{
_FirstName = value;
}
}
private String _LastName;
public String LastName
{
get
{
return _LastName;
}
set
{
_LastName = value;
}
}
private String _Address;
public String Address
{
get
{
return _Address;
}
set
{
_Address = value;
}
}
private String _State;
public String State
{
get
{
return _State;
}
set
{
_State = value;
}
}
private String _City;
public String City
{
get
{
return _City;
}
set
{
_City = value;
}
}
private String _ZIP;
public String ZIP
{
get
{
return _ZIP;
}
set
{
_ZIP = value;
}
}
public void Add1()
{
newprospect = new Prospect();
newprospect.ID = Guid.NewGuid();
newprospect.FirstName = FirstName;
newprospect.LastName = LastName;
newprospect.Address = Address;
newprospect.State = State;
newprospect.City = City;
newprospect.ZIP = ZIP;
prospect = newprospect;
ctx2.AddToProspects(prospect);
Prospects.Add(newprospect);
}
public event PropertyChangedEventHandler PropertyChanged = delegate { };
private void RaisePropertyChanged(string property) { PropertyChanged(this, new PropertyChangedEventArgs(property)); }
}
}
我的看法 xamal:
<Window x:Class="Wpfentity3.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
WindowStartupLocation="CenterScreen"
Title="Prospects"
Height="482" Width="500" MaxWidth="500" MaxHeight="600"
xmlns:cusns="clr-namespace:Wpfentity3">
<StackPanel Height="290" VerticalAlignment="Top">
<StackPanel Orientation="Horizontal" >
<Label
Content="Prospects"
BorderBrush="Blue" BorderThickness="1"
HorizontalAlignment="Left" VerticalAlignment="Top"
FontSize="24" FontFamily="Comic Sans MS"
Padding="13,3,13,9" Margin="5"
Foreground="Purple" Background="LemonChiffon" />
<Label
Content="{Binding Path=label}" Foreground="Red" FontSize="14"
HorizontalAlignment="Right" VerticalAlignment="Center"
Height="auto" Margin="180,0,10,0" />
</StackPanel>
<Grid
HorizontalAlignment="Left" VerticalAlignment="Top"
Height="120" Width="475" >
<Grid.RowDefinitions>
<RowDefinition Height="25*" />
<RowDefinition Height="25*" />
<RowDefinition Height="25*" />
<RowDefinition Height="25*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="90*" />
<ColumnDefinition Width="135*" />
<ColumnDefinition Width="45*" />
<ColumnDefinition Width="32*" />
<ColumnDefinition Width="57*" />
<ColumnDefinition Width="118*" />
</Grid.ColumnDefinitions>
<Label
Content="First name"
Grid.Row="0" Grid.Column="0" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtFirstName"
Grid.Column="1"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding Path=FirstName}"
Width="130" />
<Label
Content="Last name"
Grid.Row="1" Grid.Column="0" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtLastName"
Grid.Row="1" Grid.Column="1"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding LastName}"
Width="130" />
<Label
Content="Address"
Grid.Row="2" Grid.Column="0" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtAddress"
Grid.Row="2" Grid.Column="1"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding Address}"
Width="300" Grid.ColumnSpan="5" />
<Label
Content="City"
Grid.Row="3" Grid.Column="0" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtCity"
Grid.Row="3" Grid.Column="1"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding City}"
Width="130" />
<Label
Content="State"
Grid.Row="3" Grid.Column="2" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtState"
Grid.Row="3" Grid.Column="3" Width="30" MaxLength="2" CharacterCasing="Upper" Text="{Binding State}"
HorizontalAlignment="Left" VerticalAlignment="Center" />
<Label
Content="ZIP code"
Grid.Row="3" Grid.Column="4" Margin="0,0,5,0"
HorizontalAlignment="Right" VerticalAlignment="Center" />
<TextBox Name="txtZIP"
Grid.Row="3" Grid.Column="5" MaxLength="10"
HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding ZIP}"
Width="90" />
</Grid>
<StackPanel Orientation="Horizontal" Margin="0,10,0,0">
<Button Name="btnFind"
Content="_Find"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnAdd"
Content="_Add" Command="{Binding Commands.Add}"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnEdit"
Content="_Edit"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnDelete"
Content="_Delete"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnSave"
Content="_Save"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnCancel"
Content="_Cancel"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0" />
<Button Name="btnClose"
Content="Cl_ose"
Width="auto" Margin="5,0,5,0" Padding="10,0,10,0"
/>
</StackPanel>
<StackPanel Height="34" Margin="10">
<Grid Margin="10">
<ListView Name="lvprospects" ItemsSource="{Binding Prospects}" Margin="0,0,0,-200">
<ListView.View>
<GridView>
<GridViewColumn Header="FirstName" Width="120" DisplayMemberBinding="{Binding FirstName}" />
<GridViewColumn Header="LastName" Width="50" DisplayMemberBinding="{Binding LastName}" />
<GridViewColumn Header="Address" Width="50" DisplayMemberBinding="{Binding Address}" />
<GridViewColumn Header="City" Width="50" DisplayMemberBinding="{Binding City}" />
<GridViewColumn Header="State" Width="50" DisplayMemberBinding="{Binding State}" />
<GridViewColumn Header="ZIP" Width="50" DisplayMemberBinding="{Binding ZIP}" />
</GridView>
</ListView.View>
</ListView>
</Grid>
</StackPanel>
</StackPanel>
如果您要将视图绑定到 ViewModel 中的集合，我建议使用 ObservableCollection。
ObservableCollection 实现了 INotifyCollectionChanged，它会在添加或删除元素时通知视图。
有了这个，您就不需要 "FillProspects" 方法和 "RaisePropertyChanged("Prospects")".
如果您想了解更多信息，我建议您发布如何绑定 XAML 以及如何构建 "Prospects" 对象（我们甚至不知道它是什么类型，我只是假设它不是ObservableCollection).
编辑：
您将 ListView 绑定到 "Prospects"，但在您的 ViewModel 中，我看到 "Prospects" 是 "List" 类型，它需要是 "ObservableCollection"。我看到您有一个名为 "prospects" 的 ObservableCollection，但您没有在任何地方使用它。这可能是问题所在吗？
可以将新项目添加到数据库，然后使用相同的刷新方法再次检索集合FillProspects：
你做的基本上是正确的。
将 Prospects 属性 的类型从 List<Prospect> 更改为 ObservableCollection<Prospect>:
private ObservableCollection<Prospect> _prospects = new ObservableCollection<Prospect>();
public ObservableCollection<Prospect> Prospects
{
get
{
return _prospects;
}
set
{
_prospects = value;
RaisePropertyChanged("Prospects");
}
}
并在您的 Add1 方法中将新的 Prospect 对象添加到该集合中：
public void Add1()
{
newprospect = new Prospect();
newprospect.ID = Guid.NewGuid();
newprospect.FirstName = FirstName;
newprospect.LastName = LastName;
newprospect.Address = Address;
newprospect.State = State;
newprospect.City = City;
newprospect.ZIP = ZIP;
prospect = newprospect;
ctx2.AddToProspects(prospect);
Prospects.Add(newprospect);
}
仅将其添加到 DbContext 不会影响 ListView。