WPF

Question

我的应用程序有问题，尤其是 WPF MVVM 中的绑定。我创建了模型、视图模型和视图，这是我的代码的一部分（只有这与我的问题有关）当我单击 nemed 按钮时：PointUp 我想查看 Team1 点数。谁能告诉我我做错了什么？

查看

    <Window x:Class="Tabu.Game
        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:Tabu"
        xmlns:vm="clr-namespace:Tabu.ViewModel"
        mc:Ignorable="d"
        Title="Game"  Height="600" Width="900" Background="Beige">
    <Window.DataContext>
        <vm:TeamStatistic />
    </Window.DataContext>
    <Grid>
        <Button x:Name="PointUp" Command="{Binding AddPoints }" Content="+"/>
        <Label x:Name="PointsTeam1_label" Content="{Binding Team1.TeamPoints, UpdateSourceTrigger=PropertyChanged }"/>
</Grid>

型号

'

namespace Tabu.Model
{
    public class Team
    {
        public bool IsTeamActive { get;  set; }
        public int TeamMiss { get;  set; }
        public int TeamPoints { get;  set; }
        public int TeamMistake { get;  set; }
    }
}

'

视图模型

namespace Tabu.ViewModel
{
    class TeamStatistic : INotifyPropertyChanged

    {
        public Team Team1 = new Team();

        public int TeamPoints
        {
            get { return TeamPoints; }
            set { TeamPoints = value; OnPropertyChanged("TeamPoints"); }
        }

        public ICommand AddPoints
        {
            get { return new RelayCommand(() => Add_Points()); }
        }

        public void Add_Points()
        {
            Team1.TeamPoints++;
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged(params string[] propsName)
        {
            if (PropertyChanged!=null)
            {
                foreach(string propName in propsName)
                PropertyChanged(this, new PropertyChangedEventArgs(propName));
            }
        }
    }

public class RelayCommand : ICommand
    {
        private readonly Func<bool> canExecute;
        private readonly Action execute;

        public RelayCommand(Action execute)
            : this(execute, null) { }

        public RelayCommand(Action execute, Func<bool> canExecute)
        {
            if (execute == null) throw new ArgumentNullException("execute");
            this.execute = execute;
            this.canExecute = canExecute;
        }

        public event EventHandler CanExecuteChanged
        {
            add { if (this.canExecute != null) CommandManager.RequerySuggested += value; }
            remove { if (this.canExecute != null) CommandManager.RequerySuggested -= value; }
        }

        public Boolean CanExecute(object parameter) { return this.canExecute == null ? true : this.canExecute(); }
        public void Execute(object parameter) { this.execute(); }
    }
}

Answer 1

问题在这里：

public int TeamPoints
{
    get { return TeamPoints; } //should be Team1.TeamPoints
    set { TeamPoints = value; OnPropertyChanged("TeamPoints"); } //should be Team1.TeamPoints
}

在 TeamPoints 属性中 ViewModel 中 return 并设置与 ViewModel 相同的属性 TeamPoints 但是您应该从 Model (Team1) 开始设置。您应该 return 并设置 Team1.TeamPoints.

public int TeamPoints
{
    get { return Team1.TeamPoints; }  
    set { Team1.TeamPoints = value; OnPropertyChanged("TeamPoints"); }
}

和Add_Points()：

public void Add_Points()
{
    Team1.TeamPoints++;
    OnPropertyChanged("TeamPoints");
}

Answer 2

我估计是因为AddPoints（命令绑定）。由于此命令已绑定并且您正在创建 RelayCommand 的实例并在每次它可能会破坏绑定时返回。

使用 CommandBindings 的一个更好的替代方法是声明属性并在视图模型的构造函数中初始化它们。

例如：

namespace Tabu.ViewModel
{
  class TeamStatistic : INotifyPropertyChanged

  {
    public Team Team1 = new Team();

    public int TeamPoints
    {
        get { return Team1.TeamPoints; }
        set { Team1.TeamPoints = value; OnPropertyChanged("TeamPoints"); }
    }

    private ICommand _AddPoints;

    public ICommand AddPoints
    {
        get { return _AddPoints; }
        set { _AddPoints = value; }
    }

    public void Add_Points()
    {
        Team1.TeamPoints++;
    }

    public TeamStatistic ()
    {
        _AddPoinss = new RelayCommand(Add_Points);
    }

    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(params string[] propsName)
    {
        if (PropertyChanged!=null)
        {
            foreach(string propName in propsName)
            PropertyChanged(this, new PropertyChangedEventArgs(propName));
        }
    }
}

Answer 3

您必须像这样更新您的绑定。

<Label x:Name="PointsTeam1_label" Content="{Binding TeamPoints, UpdateSourceTrigger=PropertyChanged }"/>

当您绑定到 Team1.TeamPoints 时，您将不会从您的 TeamPoints 属性.

中的 OnPropertyChanged 获得通知

WPF - MVVM 绑定

WPF - MVVM Bindings

c#

mvvm