我是WPF的新手，我需要快速帮助。
我想要实现的是，如果datagrid selected item不为null，则更新记录，如果为null，则插入新记录。我想用命令
来实现这一点下面是模型。数据库管理类实现INotifyPropertyChanged
class User:DatabaseManagement
{
#region VARIABLES
private int userID;
private string firstName;
private string lastName;
private string email;
DataTable dt;
#endregion
#region PROPERTIES
public int UserID
{
get { return userID; }
set { userID = value;
onPropertyChanged("UserID");
}
}
public string FirstName
{
get { return firstName; }
set { firstName = value;
onPropertyChanged("FirstName");
}
}
public string LastName
{
get { return lastName; }
set { lastName = value;
onPropertyChanged("LastName");
}
}
public string Email
{
get { return email; }
set { email = value;
onPropertyChanged("Email");
}
}
#endregion
public User()
{
}
public User(int userid, string firstname, string lastname, string email)
{
UserID = userid;
FirstName = firstname;
LastName = lastname;
Email = email;
}
}
这是VIEW MODEL
class UserVM : ViewModelBase
{
#region VARIABLES
private ObservableCollection<User> user_list = new ObservableCollection<User>();
private User selecteduser;
private DataTable dtusers;
private User obj_user;
private ICommand cmdupdateuser;
private ICommand cmdnewuser;
#endregion
#region PROPERTIES
public ObservableCollection<User> UserList
{
get { return user_list; }
set {
user_list = value;
onPropertyChanged("UserList");
}
}
public User SelectedUser
{
get { return selecteduser; }
set
{
selecteduser = value;
onPropertyChanged("SelectedUser");
}
}
public ICommand UpdateUserCommand
{
get { return cmdupdateuser; }
set
{
cmdupdateuser = value;
onPropertyChanged("UpdateUserCommand");
}
}
public ICommand NewUserCommand
{
get { return cmdnewuser; }
set
{
cmdnewuser = value;
onPropertyChanged("NewUserCommand");
}
}
#endregion
#region CONSTRUCTOR
public UserVM()
{
getAllUsers();
UpdateUserCommand = new RelayCommand(new Action<object>(updateUser));
}
#endregion
#region FUNCTIONS
private void getAllUsers()
{
obj_user = new User();
dtusers = obj_user.getAllUsers();
foreach (DataRow row in dtusers.Rows)
{
UserList.Add(
new User(
Convert.ToInt16(row["UserID"]),
row["FirstName"].ToString(),
row["LastName"].ToString(),
row["Email"].ToString()
)
);
}
}
public void updateUser(object parameters)
{
User selecteduser = SelectedUser;
int rows = obj_user.updateUser(selecteduser);
if (rows > 0)
{
UserList.Clear();
getAllUsers();
}
}
#endregion
}
这是我的观点
<Page x:Class="IMS.View.PageUser"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:user="clr-namespace:IMS.ViewModel"
mc:Ignorable="d"
x:Name="pageuser"
d:DesignHeight="477" d:DesignWidth="695"
Title="PageUser" Loaded="Page_Loaded">
<Page.Resources>
<user:UserVM x:Key="UserVM"></user:UserVM>
</Page.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="200" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition MinWidth="500" />
</Grid.ColumnDefinitions>
<DataGrid AutoGenerateColumns="False" Grid.Column="0" Height="Auto" HorizontalAlignment="Stretch" Margin="0" Name="userdatagrid" VerticalAlignment="Stretch" Width="Auto"
DataContext="{Binding Source={StaticResource UserVM}}"
ItemsSource="{Binding Path=UserList}" SelectionChanged="dataGrid1_SelectionChanged"
SelectedItem="{Binding SelectedUser}" CanUserAddRows="False" CanUserDeleteRows="False">
<DataGrid.Columns>
<DataGridTextColumn Header="User ID" Binding="{Binding UserID}" />
<DataGridTextColumn Header="Name" Binding="{Binding FirstName}" />
</DataGrid.Columns>
</DataGrid>
<GridSplitter Grid.Column="1" Height="Auto" HorizontalAlignment="Right" Margin="0" Name="gridSplitter1" VerticalAlignment="Stretch" Width="10" ResizeDirection="Columns" ResizeBehavior="PreviousAndNext" Background="#FFEB3333" />
<DockPanel Grid.Column="2" Height="Auto" Name="dockPanel1" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Width="Auto">
<Menu Grid.Column="2" Height="25" HorizontalAlignment="Stretch" Margin="0" Name="menu1" VerticalAlignment="Top" Width="Auto" DockPanel.Dock="Top" DataContext="{Binding Source={StaticResource UserVM}}">
<MenuItem Header="New" Click="MI_New_Click" />
<MenuItem Header="Save" Command="{Binding UpdateUserCommand}" />
</Menu>
<Grid Height="Auto" Name="grid1" Width="Auto" DockPanel.Dock="Top" DataContext="{Binding Source={StaticResource UserVM}}">
<Grid.RowDefinitions>
<RowDefinition Height="38*" />
<RowDefinition Height="44*" />
<RowDefinition Height="45*" />
<RowDefinition Height="46*" />
<RowDefinition Height="43*" />
<RowDefinition Height="236*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="142*" />
<ColumnDefinition Width="358*" />
</Grid.ColumnDefinitions>
<Label Content="First Name:" Height="28" HorizontalAlignment="Left" Margin="6,7,0,0" Name="lblfirstname" VerticalAlignment="Top" />
<Label Content="Last Name:" Grid.Row="1" Height="28" HorizontalAlignment="Left" Margin="6,6,0,0" Name="lbllastname" VerticalAlignment="Top" />
<Label Content="Email:" Grid.Row="2" Height="28" HorizontalAlignment="Left" Margin="6,11,0,0" Name="lblemail" VerticalAlignment="Top" />
<TextBox Grid.Column="1" Height="23" HorizontalAlignment="Left" Margin="8,7,0,0" Name="txtfirstname" VerticalAlignment="Top" Width="120"
Text="{Binding Path=SelectedUser.FirstName}" />
<TextBox Grid.Column="1" Grid.Row="1" Height="23" HorizontalAlignment="Left" Margin="8,11,0,0" Name="txtlastname" VerticalAlignment="Top" Width="120"
Text="{Binding ElementName=userdatagrid, Path=SelectedItem.LastName}"/>
<TextBox Grid.Column="1" Grid.Row="2" Height="23" HorizontalAlignment="Left" Margin="8,16,0,0" Name="txtemail" VerticalAlignment="Top" Width="120"
Text="{Binding ElementName=userdatagrid, Path=SelectedItem.Email}"/>
</Grid>
</DockPanel>
</Grid>
</Page>
请帮助我如何实现这一目标。我不允许插入图像，因为我是stackoverflow的新用户。提前致谢
答案 0 :(得分：0)
1）在XAML中创建一个新按钮
2）在UserVM类中创建一个新命令（称之为UpdateOrAddNew命令）并使用“Command”属性将其与按钮关联。
有关详情，请参阅此处：How to bind WPF button to a command in ViewModelBase?
3）在您的UpdateOrAddNew命令处理程序中，检查SelectedUser是否为null（然后创建新用户），或者如果它不为null，则更新现有用户。
要了解TextBox问题，您需要创建一个始终包含信息的包装器。
将此添加到您的UserVM：
public User UserRecord
{
get
{
if(userRecord == null)
return userRecord = new User();
}
set
{
userRecord = value;
onPropertyChanged("UserRecord");
}
}
现在你需要修改TextBoxes以绑定UserRecord而不是SelectedUser。
并修改您的SelectedUser：
public User SelectedUser
{
get { return selecteduser; }
set
{
selecteduser = value;
onPropertyChanged("SelectedUser");
UserRecord = selecteduser;
}
}