如何自定义枚举描述绑定到DataGrid [英] How to bind a custom Enum description to a DataGrid

问题描述

问题：我有其中有描述标签在下面的样式枚举类型：[URL =htt​​p://xml.indelv.com/data-binding-enum.html]描述标签教程[/ URL]。我从我拉数据（整数然后卡斯廷来枚举），然后被绑定到一个DataGrid一个Windows SQL Server数据库。取而代之的拉动和套管的枚举类型，我想，以显示与它在枚举类型相关的描述标签。

Problem: I have an enumerated type which has description tags in the following style: [URL="http://xml.indelv.com/data-binding-enum.html"]description tag tutorial[/URL] . I have a Windows SQL Server Database from which I am pulling the data (as integers then castine to Enums) which is then being bound to a datagrid. Instead of pulling and casing the enumerated types, I would like to display the description tag associated with it in the enumerated type.

下面是ASP -

Here is the 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>

下面是code为绑定 -

Here is the code for the Bind -

[code]

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();
        }

[/ code]

下面是枚举类 -

[code]

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#

[/ code]

其明显的，人们可以写一个广泛的方法也做我想要什么，但有一个更合适的方法？

Its obvious that one could write an extensive method do do what i want, but is there a neater way?

推荐答案

总结起来就飞和微妙地改变你的的SelectedItem的处理（或任何你正在使用）

我的例子使用了已经present Description属性。

Wrap them up on the fly and subtly change your handling of the SelectedItem (or whatever you are using)
My example uses the already present Description attribute.

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;
    }
}

使用例子：

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);

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