如何将自定义枚举描述绑定到 DataGrid

Question

问题：我有一个枚举类型，它具有以下样式的描述标签： [URL="http://xml.indelv.com/data-binding-enum.html"]description tag tutorial[/URL] 。我有一个 Windows SQL Server 数据库，我从中提取数据（作为整数然后 castine 到枚举），然后将其绑定到数据网格。我不想在枚举类型中拉出和封装枚举类型，而是想在枚举类型中显示与其关联的描述标签。

这是 ASP -

<asp:GridView ID="StatementGrid" runat="server" AutoGenerateColumns="false" DataKeyNames="statementID" OnRowDeleting="StatementGrid_onDeleting" AllowSorting="False">
                <Columns>
                    <asp:BoundField HeaderText="Type" SortExpression="type" DataField="TypeOfStatement" />
                    <asp:HyperLinkField HeaderText="Statement" DataTextField="StatementText" DataNavigateUrlFormatString="~/Gateway/Statements/View.aspx?statementID={0}" SortExpression="statement" DataNavigateUrlFields="statementID" />
                    <asp:HyperLinkField DataNavigateUrlFields="statementID" DataNavigateUrlFormatString="~/Gateway/Statements/Update.aspx?statementID={0}" NavigateUrl="~/Gateway/Statements/Update.aspx" HeaderText="Edit" Text="<img src='../../Images/News/news_edit.gif' alt='Edit Statement'/>" />
                    <asp:TemplateField HeaderText="Delete">
                        <ItemTemplate>
                            <asp:ImageButton AlternateText="Delete Statement" ID="DeleteButton" ImageUrl="~/Images/News/news_delete.gif" runat="server" CommandName="Delete" OnClientClick="javascript:return confirm('Are you sure you want to delete this statement?');" />
                        </ItemTemplate>
                    </asp:TemplateField>
                </Columns>
                <EmptyDataTemplate>
                    There are no statements to display.
                </EmptyDataTemplate>
            </asp:GridView>

这是绑定的代码 -

[代码]

private void BindData()
        {
            IStatementDao statementDao = DaoFactory.GetStatementDao();
            List<Statement> statements;

            if (Page.Request.RawUrl.Contains("Gateway"))
            {
                statements = statementDao.GetAll();

                StatementGrid.HeaderStyle.CssClass = "GatewayGridHeader";
                StatementGrid.AlternatingRowStyle.CssClass = "GatewayGridAlternatingRow";

            }
            else
            {
                // This should never be reached but it keeps the compiler happy!!
                statements = statementDao.GetAll();
            }

            StatementGrid.DataSource = statements;
            StatementGrid.DataBind();
            DisplayTypeDescriptors();
        }

[/代码]

这里是枚举类-

[代码]

public enum TypeOfStatement 
        { 
            [EnumDescription("Dress Code")] DressCode = 1,
            [EnumDescription("Lunch Time")] LunchTime = 2,
            [EnumDescription("Footwarez")] Footware = 3,
            [EnumDescription("achtung")] Warning = 4,
            [EnumDescription("Banarna")] Banana = 5,
            [EnumDescription("Apfel")] Apple = 6
        };c#

[/代码]

很明显，可以编写一个广泛的方法来做我想做的事，但是有没有更简洁的方法？

Answer 1

即时将它们包装起来，并巧妙地改变您对 SelectedItem（或您正在使用的任何东西）的处理
我的示例使用了已经存在的 Description 属性。

public class DescriptiveEnum<T> where T: struct
{
    private static readonly Dictionary<T,string> descriptions 
        = new Dictionary<T,string>();

    static DescriptiveEnum()
    {
        foreach (FieldInfo field in
            typeof(T).GetFields(BindingFlags.Static 
            | BindingFlags.GetField | BindingFlags.Public))
        {
        descriptions.Add((T)field.GetRawConstantValue(),
            LookupName(field));         
        }
    }

    public readonly T Value;

    public DescriptiveEnum(T value)
    {
        this.Value = value;     
    }

    public override string ToString()
    {
        string s;
        if (!descriptions.TryGetValue(this.Value, out s))
        {           
        // fall back for non declared fields
        s = this.Value.ToString();  
        descriptions[this.Value] = s;
        }
        return s;
    }

    private static string LookupName(FieldInfo field)        
    {
        object[] all = field.GetCustomAttributes(
             typeof(DescriptionAttribute), false);
        if (all.Length == 0)
            return field.Name; // fall back
        else
            return ((DescriptionAttribute)all[0])
                .Description; // only one needed
    }   

    public static BindingList<DescriptiveEnum<T>> Make(
        IEnumerable<T> source)
    {
        var list = new BindingList<DescriptiveEnum<T>>();
        foreach (var x in source)
        list.Add(new DescriptiveEnum<T>(x));
        return list;
    }
}

示例用法：

public enum Foo
{
    [Description("flibble")]
    Bar,
    [Description("wobble")]
    Baz,
    // none present, will use the name
    Bat

}

Form f = new Form();
f.Controls.Add(new ListBox() 
{
    Dock = DockStyle.Fill,
    DataSource = DescriptiveEnum<Foo>.Make(
       new Foo[] { Foo.Bar, Foo.Baz, Foo.Bat }),
});
Application.Run(f);