mvvm 中的 ComboBox 静态值绑定

Question

我有一个 comboBox，其值为 [day,weeks,months,years]

   <ComboBox Width="130" Margin="0,10,0,16" ItemsSource="{Binding PeriodCollection }" 
               SelectedItem="{Binding SelectedDuration }" 
               Text=""  DisplayMemberPath="Name" />

在 comboBox 旁边，我有一个文本框。如果用户从组合框中选择“周”并将值 2 放入文本框中，则在数据库中我必须保存 2*7 = 14 [天]。

为了实现这个功能，我创建了周期集合。

 public class Period : BaseObject
    {
        private string name;
        public string Name 
        { 
            get { return name; } 
            set { name = value; NotifyPropertyChanged(); } 
        }

        private int numberOfDays;
        /// <summary>
        /// number of days in period
        /// </summary>
        public int NumberOfDays 
        { 
            get { return numberOfDays; } 
            set { numberOfDays = value; NotifyPropertyChanged(); } 
        }        

        public Period(string perdioName, int numberOfDayInPeriod)
        {
            Name = perdioName;
            NumberOfDays = numberOfDayInPeriod;
        }
    }
}
 public static class PeriodManager
{
    private static ObservableImmutableList<Period> periodCollection;
    /// <summary>
    /// return a collection of time period in days        /// 
    /// </summary>
    /// <returns>Days, Week,Month, year</returns>
    public static ObservableImmutableList<Period> GetPeriodCollection()
    {
        if (periodCollection == null)
        {
            periodCollection = new ObservableImmutable.ObservableImmutableList<Entities.Period>();
            periodCollection.Add(new Period("Days", 1));
            periodCollection.Add(new Period("Week", 7));
            periodCollection.Add(new Period("Month", 30));
            periodCollection.Add(new Period("Year", 365));
        }
        return periodCollection;
    }

    /// you can create method can return a period from a day number...

}

现在在我的 viewModel 中，我正在尝试实现一个返回天数的方法。

private ObservableImmutableList<Period> periodCollection;
public ObservableImmutableList<Period> PeriodCollection { get { return periodCollection; } set { periodCollection = value; NotifyPropertyChanged(); } }

private Period selectedDuration;
public Period SelectedDuration { get { return selectedDuration; } set { selectedDuration = value; NotifyPropertyChanged(); } }

private void GetPeriod()
{
    PeriodCollection =  PeriodManager.GetPeriodCollection();
    //here I need to write logic to merge from both values [ txtBox+combox]
}

但我对 -

感到困惑

在保存如何将文本框值与组合框天的返回值合并时[如果在文本框中输入 2 并在组合框中选择周，我需要值 14]

请在 wpf mvvm 概念中帮助我。我在 web 中尝试过，但在 mvvm 中找不到任何内容。

Answer 1

在您的视图模型中，您需要添加另一个将与文本框绑定的属性，以便您可以在视图模型中访问 TextBox 的值，所以首先添加您的视图模型中的新属性：

private ObservableImmutableList<Period> periodCollection;
public ObservableImmutableList<Period> PeriodCollection 
{ 
   get { return periodCollection; } 
   set { periodCollection = value; NotifyPropertyChanged(); } 
}

private Period selectedDuration;
public Period SelectedDuration 
{ 
  get { return selectedDuration; } 
  set { selectedDuration = value; NotifyPropertyChanged(); } 
}

private int _providedNumber;
public int ProvidedNumber
{ 
  get { return _providedNumber; } 
  set { _providedNumber= value; NotifyPropertyChanged(); } 
}

private void GetPeriod()
{
    PeriodCollection =  PeriodManager.GetPeriodCollection();
    //here I need to write logic to merge from both values [ txtBox+combox]
}

并在 xaml sepcify 中将 TextBox 与属性绑定：

<TextBox Text="{Binding Path=ProvidedNumber}"></TextBox>

现在在GetPeriod 方法中，您既可以拥有价值，又可以做任何业务需求：

private void GetPeriod()
{
    PeriodCollection =  PeriodManager.GetPeriodCollection();

    var value = _providedNumber * selectedDuration.NumberOfDays;
}