从用户输入向 xamarin forms 中的 class 列表添加元素

Question

我有这个 class：

public class Player
    {
        public int PlayerID { get; set; }
        public string PlayerName { get; set; }
        public string PlayerTime { get; set; }
        public int PlayerRank { get; set; }

    }

此列表包含播放器 class

public List<Player> PlayersTable { get; set; }
 PlayersTable = new List<Player>();

玩家 class 成员的值将来自不同的来源： PlayerName 将来自 xaml 中的用户输入“条目” - 将生成 PlayerID - PlayerTime 将来自秒表 - PlayerRank 将来自比较最佳时间

问题是：如何将来自不同来源的所有玩家数据添加到列表中？ 我知道通过以下代码完成的硬编码：

PlayersTable = new List<Player>();
            {
                new Player()
                {
                    PlayerID = 1,
                    PlayerName = "Yasir",
                    PlayerRank = 1,
                    PlayerTime = "11"
                },
                new Player()
                {
                    PlayerID = 1,
                    PlayerName = "Ahmed",
                    PlayerRank = 2,
                    PlayerTime = "13"
                }
        

但是如何从源中添加它（例如 PlayerName 将来自 xaml 条目的用户输入： <Entry Text="{Binding PlayerName}"/> .. PlayerTime 将来自 Timer 的 (timer.Elapsed)，谢谢

Answer 1

不确定您的代码中的 rest 是怎样的，但假设您想在 Entry 中输入玩家名称时添加一个新玩家，您需要添加一个命令以在用户按下返回键时运行。

<Entry Text="{Binding PlayerName}" ReturnCommand="{Binding CommandComplete}"></Entry>

然后在您的 ViewModel 中实现该命令，其中您有一个播放器列表的实例：

public partial class MyViewModel: INotifyPropertyChanged
    {
        public List<Player> PlayersTable { get; set; }
        private int PlayerID { get; set; }
        public string PlayerName { get; set; }
        private string PlayerTime { get; set; }
        private int PlayerRank { get; set; } 

        public System.Windows.Input.ICommand CommandComplete { get; set; }

        public MyViewModel()
        {
            PlayersTable = new List<Player>();

            CommandComplete = new Command(() => 
                {
                    PlayerID = GeneratePlayerID(); // assuming you implemented something like this
                    PlayerRank = GetPlayerRank(); // assuming you implemented something like this
                    PlayerTime = GetPlayerTime(); // assuming you implemented something like this
                    Player player = new Player()
                    {
                        PlayerID = this.PlayerID,
                        PlayerName = this.PlayerName,
                        PlayerRank = this.PlayerRank,
                        PlayerTime = this.PlayerTime
                    };
                    PlayersTable.Add(player);
                }
            );
        }

      // the rest of the implementation of MyViewModel
    }

Answer 2

首先，我建议您使用ObservableCollection<Player>代替List<Player> ，因为ObservableCollection Class代表一个动态数据集合，它在添加、删除或刷新整个列表时提供通知。

然后我做一个简单的，你可以看看：

 <StackLayout>
        <Label Text="PlayerName :" />
        <Entry x:Name="entry1" />

        <Button
            x:Name="btnadd"
            Command="{Binding addcommand}"
            Text="add data" />

        <ListView ItemsSource="{Binding PlayersTable}">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <StackLayout Orientation="Horizontal">
                            <Label Text="{Binding PlayerName}" />
                            <Label Text="{Binding PlayerTime}" />
                            <Label Text="{Binding PlayerRank}" />

                        </StackLayout>
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
    </StackLayout>

public partial class Page25 : ContentPage
{
    public ObservableCollection<Player> PlayersTable { get; set; }
    public Command addcommand { get; }
    public Page25()
    {
        InitializeComponent();

        PlayersTable = new ObservableCollection<Player>()
        {
             new Player() {PlayerID = 1, PlayerName = "Yasir", PlayerRank = 1, PlayerTime = "11" },
             new Player() {PlayerID = 1, PlayerName = "Ahmed", PlayerRank = 2, PlayerTime = "13" }
        };

        //add one test data to test.
        addcommand = new Command(()=> {
            Player player = new Player();
            if(!string.IsNullOrEmpty(entry1.Text))
            {
                player.PlayerName = entry1.Text;
                //get PlayerID by method.
                player.PlayerID = 0;
                //get PlayerTime by method or you can also get value from stopwatch.Don't know how do you use stopwatch.
                player.PlayerTime = "test";
                //get PlayerRank by method.
                player.PlayerRank = 0;
                PlayersTable.Add(player);
            }          
        
        });
        this.BindingContext = this;
    }
 
   
}