c# - 将 Viewmodel 绑定(bind)到 View

Question

MainWindow.xaml

<Window x:Class="SDT.MainWindow"
        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:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
        mc:Ignorable="d"
        xmlns:viewModels="clr-namespace:SDT.ViewModels"
        Height="500" Width="700" WindowStyle="None" AllowsTransparency="False" ResizeMode="NoResize" Background="#FF2C2C2C"
        TextElement.Foreground="{DynamicResource MaterialDesignBody}" TextElement.FontWeight="SemiBold">

    <Window.DataContext>
        <viewModels:UserViewModel />
    </Window.DataContext>

    <Grid>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="308,90,0,0" TextWrapping="Wrap" Text = "{Binding Login}" VerticalAlignment="Top" Width="120"/>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="152,200,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120" Text="{Binding Path=FirstName, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"/>
        <Button Content="Submit" Command="{Binding SubmitLoginDataCommand}" HorizontalAlignment="Left" Margin="567,259,0,0" VerticalAlignment="Top" Width="75"/>
    </Grid>
</Window>

MainWindows.cs

public partial class MainWindow : Window
{
    UserViewModel userViewModel = new UserViewModel();
    public MainWindow()
    {
        InitializeComponent();
        DataContext = userViewModel;

    }
}

UserViewmodel

public class UserViewModel : INotifyPropertyChanged
{
    private UserService userService = new UserService();

    public string _firstName;

    public string Login { get; set; }

    public void SubmitLoginData(object loginData)
    {
        userService.CheckUserExist(Login);
    }

    public ICommand SubmitLoginDataCommand => new RelayCommand(SubmitLoginData, param => true);

    public string FirstName
    {
        get { return _firstName; }
        set
        {
            if (_firstName != value)
            {
                _firstName = value;
                OnPropertyChanged("FirstName");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string name)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
    }
}

你好。
FirstName 绑定(bind)有什么问题？
文本框什么都不显示。
公共(public)字符串名字{} - 这里的名字在调试中有值(value)。
我试过没有 Window.DataContext 并且仅适用于 文本="{绑定(bind)名字}"但没有成功。
登录绑定(bind)工作正常。

Answer 1

您需要从 中删除MainWindow.xaml 这部分:
<Window.DataContext>
<viewModels:UserViewModel />
</Window.DataContext>
因为你有两次 DataContext，
在 xaml 和 cs 中，因此不知道从哪里获取数据。