如何从Xamarin表单的ViewModel中获取数字输入

如何解决如何从Xamarin表单的ViewModel中获取数字输入

运行命令后，我需要向用户请求一个号码。这需要在视图模型中运行。我已经尝试过ACR.UserDialog，但似乎无法弄清楚如何从viewmodel调用它。

类似这样的东西：

void RemoveItem()
{ 
    int intQuantity = (dialog from user to get the quantity);
}

谢谢！

解决方法

samples展示了如何做到这一点

// Dialogs is an IUserDialogs that you pass to your VM from your page
// using UserDialogs.Instance
var result = await Dialogs.PromptAsync(new PromptConfig()

  .SetTitle("Max Length Prompt")
  .SetPlaceholder("Maximum Text Length (10)")
  .SetInputMode(InputType.Name)
  .SetMaxLength(10));

// result.Text will contain the user's response

,

是否要在viewModel中使用Command来获得类似以下结果的结果。

首先，您需要创建AbstractViewModel。

using System.ComponentModel;
using System.Runtime.CompilerServices;
using Acr.UserDialogs;

namespace MyCusListview
{
    public abstract class AbstractViewModel : INotifyPropertyChanged
    {
        protected AbstractViewModel(IUserDialogs dialogs)
        {
            this.Dialogs = dialogs;
        }


        protected IUserDialogs Dialogs { get; }


        protected virtual void Result(string msg)
        {
            this.Dialogs.Alert(msg);
        }


        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            this.PropertyChanged?.Invoke(this,new PropertyChangedEventArgs(propertyName));
        }
    }
}

然后实现此抽象类，不要忘记在视图模型构造函数中添加IUserDialogs dialogs。然后按下dialogs.PromptAsync，可以在input.Text中得到结果。

  public class PersonsViewModel: AbstractViewModel
    {   
        public ObservableCollection<Person> persons { get; set; }
        public static ObservableCollection<Person> selectItems { get; set; }

        public ICommand TextChangeCommand { protected set; get; }
       

     
        public PersonsViewModel(INavigation navigation,IUserDialogs dialogs,ContentPage page):base(dialogs)
        {

            TextChangeCommand = new Command<Person>(async (key) =>
            {
                var input = await dialogs.PromptAsync("What is your email?","Confirm Email","Confirm","Cancel");

                if (input.Ok)
                {
                    Console.WriteLine("Your email is" + input.Text);
                }

            });
        }
     }

在后台代码中绑定viewModel时，只需在初始化viewmodel时使用以下代码即可。

  public MainPage()
        {
           InitializeComponent();

            personsViewModel =  new PersonsViewModel(Navigation,UserDialogs.Instance,this);
            this.BindingContext = personsViewModel;



        }

这是运行结果。