无法将属性作为枚举绑定到 wpf mvvm 中的组合框

Question

我有以下场景：

问题：无法将属性作为枚举绑定到 wpf mvvm 中的组合框？

如何将此枚举绑定到组合框？

1.我有一个枚举。

public enum RankType
{
   StringValue1,
   StringValue2,
   StringValue3
} 

2.我在 myclass 中有一个属性作为枚举：

[DefaultValue(RankType.StringValue1)]
[ConvertUsing(typeof(EnumTypeConverter<RankType>))]
public RankType Rank { set; get; }

ConvertUsing Class，它为我做转换：

[System.AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false)]
public class ConvertUsingAttribute:Attribute
{
    private TypeConverter _converter = null;
    public TypeConverter Converter
    {
        get
        {
            if (_converter == null)
                _converter = (TypeConverter)System.Activator.CreateInstance(TypeOfConverter);
            return _converter;
        }
    }
    public Type TypeOfConverter
    {
        get;
        private set;
    }
    public ConvertUsingAttribute(Type converterType)
    {
        this.TypeOfConverter = converterType;
    }
}

EnumTypeConverter 类：

public class EnumTypeConverter<T>:TypeConverter
{
    public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
    {
        return sourceType == typeof(string);
    }
    public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
    {
        return destinationType == typeof(string);
    }
    public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
    {
        if (value != null && value is string)
        {
            return Enum.Parse(typeof(T), (string)value);// int.Parse(((string)value).Trim());
        }
        return base.ConvertFrom(context, culture, value);
    }
    public override object ConvertTo(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destinationType)
    {
        if (value != null && destinationType == typeof(string))
        {
            return ((T)value).ToString();
        }
        return base.ConvertTo(context, culture, value, destinationType);
    }
}

4.在视图模型中

private MilitaryRankType _selectedRankType;

public RankType SelectedRankType 
{  
        get { return _selectedRankType; }
        set
        {
            _selectedRankType = value;
            NotifyPropertyChanged(nameof(RankTypes));
        } 
}

private RankType[] _rankTypes;
public RankType[] RankTypes
{
    get
    {
       return _rankTypes ??
              (_rankTypes =Enum.GetValues(typeof(RankType)).Cast<RankType>().ToArray());
    }
}

5.在视图中

<ComboBox ItemsSource="{Binding RankTypes, UpdateSourceTrigger=PropertyChanged, NotifyOnValidationError=True, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" SelectedItem="{Binding SelectedRankType}" />

6.我在xaml中使用了listview

   <ListView ItemsSource="{Binding EmployeesList}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="3">
                        <ListView.View>
                            <GridView>
                                <GridViewColumn Width="150" Header="">
                                    <GridViewColumn.CellTemplate>
                                        <DataTemplate>
                                            <TextBox Text="{Binding Path=NationalId, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, NotifyOnValidationError=True, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" />
                                        </DataTemplate>
                                    </GridViewColumn.CellTemplate>
                                </GridViewColumn>
                                <GridViewColumn Width="150" Header="">
                                    <GridViewColumn.CellTemplate>
                                        <DataTemplate>
                                            <TextBox Text="{Binding Path=CardId, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, NotifyOnValidationError=True, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" />
                                        </DataTemplate>
                                    </GridViewColumn.CellTemplate>
                                </GridViewColumn>

                                <GridViewColumn Width="150" Header="">
                                    <GridViewColumn.CellTemplate>
                                        <DataTemplate>
                                            **<ComboBox SelectedItem="{Binding SelectedRankType}" />**
                                        </DataTemplate>
                                    </GridViewColumn.CellTemplate>
                                </GridViewColumn>

                                <GridViewColumn Width="150" Header="">
                                    <GridViewColumn.CellTemplate>
                                        <DataTemplate>
                                            <TextBox Text="{Binding Path=FirstName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, NotifyOnValidationError=True, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" />
                                        </DataTemplate>
                                    </GridViewColumn.CellTemplate>
                                </GridViewColumn>
                                <GridViewColumn Width="150" Header="">
                                    <GridViewColumn.CellTemplate>
                                        <DataTemplate>
                                            <TextBox Text="{Binding Path=LastName,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged,NotifyOnValidationError=True,ValidatesOnDataErrors=True,ValidatesOnExceptions=True}"/>
                                        </DataTemplate>
                                    </GridViewColumn.CellTemplate>
                                </GridViewColumn>

                            </GridView>
                        </ListView.View>
                    </ListView>

Answer 1

老实说，我真的不知道你的代码出了什么问题，但我可以给你一个没有任何花哨转换器的工作示例：

假设您有以下窗口内容：

<Grid x:Name="grid1">
    <ComboBox ItemsSource="{Binding SelectableRanks}" SelectedItem="{Binding SelectedRank}"/>
</Grid>

然后你在窗口构造函数中初始化数据上下文：

public MainWindow()
{
    InitializeComponent();
    grid1.DataContext = new RankSelectionVM();
}

这是你的视图模型：

public class RankSelectionVM
{
    private RankType _SelectedRank;
    public RankType SelectedRank
    {
        get { return _SelectedRank; }
        set { _SelectedRank = value; }
    }

    private RankType[] _rankTypes;
    public RankType[] SelectableRanks
    {
        get
        {
            return _rankTypes ??
                   (_rankTypes = Enum.GetValues(typeof(RankType)).Cast<RankType>().ToArray());
        }
    }
}

public enum RankType
{
    StringValue1,
    StringValue2,
    StringValue3
}

它没有任何INotifyPropertyChanged 或任何附加的转换器，但在SelectedRank 设置器中放置一个断点 - 当您选择一个值时它应该会中断。如果此代码对您有用，您必须找出您所做的不同之处才能在您的项目中获得一个不工作的代码。否则你可能会遇到一些非常奇怪的问题需要特别注意。