绑定点击命令未触发

Question

谁能指出为什么我的命令没有触发？这是我的自定义控件

public partial class RateControl : Grid
    {
        public static readonly BindableProperty RateProperty = BindableProperty.Create(nameof(Rating), typeof(int), typeof(RateControl), 1, propertyChanged: OnRatePropertyChanged);

        private static void OnRatePropertyChanged(BindableObject bindable, object oldValue, object newValue)
        {
            if(bindable is RateControl && bindable != null && newValue is int)
            {
                (bindable as RateControl).OnRateClicked((int)newValue);
            }
        }

        public int Rating
        {
            set => SetValue(RateProperty, value);
            get => (int)GetValue(RateProperty);
        }

        public ICommand OnRateSelectedCommand { get; set; }

        public RateControl()
        {
            InitializeComponent();
            OnRateSelectedCommand = new Command<int>(OnRateClicked);
        }

        private void OnRateClicked(int rating)
        {
            Rating = rating;
            ChangeStar(Rating);
        }

        private void ChangeStar(int starcount)
        {
            for (int i = 1; i <= starcount; i++)
            {
                (FindByName($"star{i}") as Label).Text = RsrIcon.StarFull;
            }

            for (int i = starcount + 1; i <= 5; i++)
            {
                (FindByName($"star{i}") as Label).Text = RsrIcon.StarEmpty;
            }
        }
    }

这是我的 Xaml

<Grid xmlns="http://xamarin.com/schemas/2014/forms" 
      xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
      x:Class="Mobile.Controls.RateControl"
      xmlns:common="clr-namespace:Mobile.Common"
      xmlns:control="clr-namespace:Mobile.Controls"
      RowDefinitions="Auto"
      x:Name="component"
      ColumnDefinitions="30,30,30,30,30"
      ColumnSpacing="10">
    
    <control:TappableLabel FontSize="Large"
                           x:Name="star1"
                           TappedCommand="{x:Binding OnRateSelectedCommand, Source={x:Reference component}}"
                           TappedCommandParameter="1"
                           Text="{Static common:RsrIcon.StarEmpty}"
                           TextColor="{StaticResource RsrYellow}"
                           VerticalOptions="Center"/>

.......

所以 TappableLabel 只是一个自定义的 TappedGesture，点击 RateControl 时，事情是 StarFull 或 StarEmpty。命令的初始化工作正常，但点击后没有任何反应。

Answer 1

我从未见过 {x:Binding ... 与 Xamarin Forms 一起使用。
将其更改为 {Binding ...:

... TappedCommand="{Binding OnRateSelectedCommand, Source={x:Reference component}}"

可选地， 在构造函数的最后一行添加：

    BindingContext = this;

然后你可以简单地用{Binding OnRateSelectedCommand}进行绑定：

... TappedCommand="{Binding OnRateSelectedCommand}"

Answer 2

Command 的通用类型应该是 string 而不是 int。

修改你的代码如下

//xaml
TappedCommand="{Binding OnRateSelectedCommand}"

public RateControl()
{
   InitializeComponent();
   OnRateSelectedCommand = new Command<string>(OnRateClicked);
   BindingContext = this;
}

private void OnRateClicked(string rating)
{

}

绑定点击命令未触发

Binded TappedCommand is not triggering

ios

xamarin