从用户输入向 xamarin forms 中的 class 列表添加元素

Question

I have this class:

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

    }

And this list containing the player class

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

the values for player class members will come from different sources: PlayerName will come from user input "Entry" in xaml - PlayerID will be generated - PlayerTime will come from stopwatch - PlayerRank will come from comparing the best time

the question is: how to add all Player data from different sources to the list? I know that hard coding done by the following code:

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

but how to add it from sources (like PlayerName will come from user input by xaml Entry: <Entry Text="{Binding PlayerName}"/> .. And the PlayerTime will come from (timer.Elapsed) for Timer, thanks

Answer 1

Not sure how the rest of your code looks like, but assuming you want to add a new player when you enter the player's name into Entry, you will need to add a command to run when the user presses the return key.

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

and then implement that command in your ViewModel where you have an instance of the list of players:

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

Firstly, I suggest you to use ObservableCollection<Player> to replace List<Player> , because ObservableCollection Class represents a dynamic data collection that provides notifications when items get added, removed, or when the whole list is refreshed.

Then I do one simple that you can take a look:

 <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;
    }
 
   
}