Enum 綁定到 CheckBox

第一種方法：

　　後臺：

 internal static class EnumCache<T> 
        where T : struct, IConvertible
    {
        private static Dictionary<int, Tuple<T, string>> collectionCache;

        public static Dictionary<int, Tuple<T, string>> CollectionCache
        {
            get
            {
                if (collectionCache == null)
                {
                    collectionCache = CreateCache();
                }
                return collectionCache;
            }
        }

        private static Dictionary<int, Tuple<T, string>> CreateCache()
        {
            Dictionary<int, Tuple<T, string>> collectionCache = new Dictionary<int, Tuple<T, string>>();

            var fields = typeof(T).GetFields().Where(x => x.IsLiteral);

            foreach (var field in fields)
            {
                var intValue = (int)field.GetValue(null);
                var displayText = ((DescriptionAttribute[])field.GetCustomAttributes(typeof(DescriptionAttribute), false))[0].Description;
                T operatorEnum = (T)(object)field.GetValue(null);
                var tuple = Tuple.Create(operatorEnum, displayText);
                collectionCache.Add(intValue, tuple);
            }
            return collectionCache;
        }
    }

    public class LogicalOperatorEnumConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            //this is a hack, binding is unbinding to text i think???
            if (value is string)
            {
                value = LogicalOperator.Where;
            }

            return EnumCache<LogicalOperator>.CollectionCache[(int)value].Item2;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var displayText = (String)value;
            var key = EnumCache<LogicalOperator>.CollectionCache.Single(x => x.Value.Item2 == displayText).Key;
            return (object)EnumCache<LogicalOperator>.CollectionCache[key].Item1;
        }
    }

前臺：

<templates:LogicalOperatorEnumConverter x:Key="LogicalOperatorEnumConverter" />
<ComboBox ToolTip="The logical operator"  Grid.Column="1" Margin="2 0 0 0" ItemsSource="{Binding LogicalOperators}" SelectedItem="{Binding LogicalOperator, Mode=TwoWay}" >
                <ComboBox.ItemTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding Path=. , Converter={StaticResource LogicalOperatorEnumConverter}}" />
                    </DataTemplate>
                </ComboBox.ItemTemplate>
            </ComboBox>

此方法為泛型方法封裝，每次用時，都要寫一個轉換器，如：LogicalOperatorEnumConverter 。 

第二種方法：

　　寫一個固定的類：

 public class ComboBoxDataModel : BaseEntity
    {
        private Guid _id;
        public Guid ID { get => _id; set => SetProperty(ref _id, value); }
        private string value;

        public string Value
        {
            get { return value; }
            set { this.value = value; OnPropertyChanged("Value"); }
        }
        private string text;

        public string Text
        {
            get { return text; }
            set { this.text = value; OnPropertyChanged("Text"); }
        }
        private bool isChecked;
        public bool IsChecked
        {
            get { return isChecked; }
            set { this.isChecked = value; OnPropertyChanged("IsChecked"); }
        }

    }

將Enum轉成ObservableCollection<ComboBoxDataModel>

/// <summary>
/// 枚舉轉換為List，顯示名稱為summary
/// </summary>
/// <param name="pEnum"></param>
/// <param name="pShowEnumValue">True:返回的是0,1，2等值；False：返回的是值對於的枚舉項目名稱</param>
/// <returns></returns>

public static ObservableCollection<ComboBoxDataModel> GetEnumList(Type pEnumType, bool pShowEnumValue = true)
        {
            ObservableCollection<ComboBoxDataModel> list = new ObservableCollection<ComboBoxDataModel>();
            Type typeDescription = typeof(DescriptionAttribute);
            System.Reflection.FieldInfo[] fields = pEnumType.GetFields();
            string strText = string.Empty;
            string strValue = string.Empty;
            foreach (FieldInfo field in fields)
            {
                if (field.FieldType.IsEnum)
                {
                    if (pShowEnumValue)
                    {
                        strValue = ((int)pEnumType.InvokeMember(field.Name, BindingFlags.GetField, null, null, null)).ToString();
                    }
                    else
                    {
                        strValue = pEnumType.InvokeMember(field.Name, BindingFlags.GetField, null, null, null).ToString();
                    }
                    object[] arr = field.GetCustomAttributes(typeDescription, true);
                    if (arr.Length > 0)
                    {
                        DescriptionAttribute aa = (DescriptionAttribute)arr[0];
                        strText = aa.Description;
                    }
                    else
                    {
                        strText = field.Name;
                    }
                    list.Add(new ComboBoxDataModel() { Text = strText, Value = strValue });
                }
            }
            return list;
        }

ViewModel：

 private ObservableCollection<ComboBoxDataModel> _enumBusinessPartDiscountTypeList;
        //數量範圍列表
        public ObservableCollection<ComboBoxDataModel> EnumBusinessPartDiscountTypeList
        {
            get => _enumBusinessPartDiscountTypeList;
            set
            {
                 SetProperty(ref _enumBusinessPartDiscountTypeList, value);
            }
        }

ctor中
 EnumBusinessPartDiscountTypeList =
                ComboBoxListHelper.GetEnumList(typeof(EnumBusinessPartDiscountType), true);

前臺：

 <ComboBox x:Name="cmbQuantitativeRange" Grid.Row="0" Grid.Column="3" DisplayMemberPath="Text" SelectedValuePath="Value"  Margin="5" Height="25"
                      ItemsSource="{Binding EnumBusinessPartDiscountTypeList}" 
                      SelectedItem="{Binding SelectedEnumBusinessPartDiscountType,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}">                            
                        </ComboBox>

這種方式也可以，但需要寫更多的代碼，項目一開始用的是第二種。後來發現第一種，感覺第一種更比較好理解點。主要還是看項目需求，來選擇。