Handling Postbacks using MenuItemTemplate

When using a MenuItemTemplate to perform a postback (instead of a navigate), handling the postback can be tricky. If you have several MenuItems, you will end up writing a lot of code to determine the menuitem that caused the postback and parsing the eventargument data.

Patrick Rodgers came up with a subclassed MenuItemTemplate in this post(http://www.thesug.org/blogs/patrickr/Lists/Posts/Post.aspx?ID=18) that targets itself for the postback and raises an event. You simply have to subscribe to the event and handle the postback there.

Here’s Patrick’s code:

using System;
using System.Web.UI;
using Microsoft.SharePoint.WebControls;

namespace Example
{
    public class PostBackEventMenuItem : MenuItemTemplate, IPostBackEventHandler
    {
        public PostBackEventMenuItem()
            : base() { }

        public PostBackEventMenuItem(string text)
            : base(text) { }

        public PostBackEventMenuItem(string text, string imageUrl)
            : base(text, imageUrl) { }

        public PostBackEventMenuItem(string text, string imageUrl, string clientOnClickScript)
            : base(text, imageUrl, clientOnClickScript) { }

        protected override void EnsureChildControls()
        {
            if (!this.ChildControlsCreated)
            {
                base.EnsureChildControls();
                if (string.IsNullOrEmpty(this.ClientOnClickUsingPostBackEvent))
                {
                    this.ClientOnClickUsingPostBackEventFromControl(this);
                }
            }
        }

        #region IPostBackEventHandler Members

        public void RaisePostBackEvent(string eventArgument)
        {
            EventHandler<EventArgs> handler = this.OnPostBackEvent;
            if (handler != null)
            {
                handler(this, new EventArgs());
            }
        }

        #endregion

        public event EventHandler<EventArgs> OnPostBackEvent;
    }
}

To use the control, register it in an aspx page, add the PostbackEventMenuItem and subscribe to the OnPostBackEvent.

<%@ Register TagPrefix="SharePoint" 
	Namespace="Microsoft.SharePoint.WebControls"
    Assembly="Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, 
	PublicKeyToken=71e9bce111e9429c" %>
<%@ Register TagPrefix="Utilities" 
	Namespace="Microsoft.SharePoint.Utilities" 
	Assembly="Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, 
	PublicKeyToken=71e9bce111e9429c" %>
<%@ Register TagPrefix="Example" 
	Namespace="Example" Assembly="Example, Version=1.0.0.0, Culture=neutral, 
	PublicKeyToken=2bb7d29b4348a50b" %>
<%@ Import Namespace="Microsoft.SharePoint" %>
<%@ Import Namespace="Microsoft.SharePoint" %>
<%@ Control Language="C#" AutoEventWireup="true" 
	ClassName="Welcome" CompilationMode="Always" %>

<script runat="server">

    protected override void OnLoad(EventArgs e)
    {
        base.OnLoad(e);
        if (HttpContext.Current.User.Identity.IsAuthenticated)
        {
            this.ExplicitLogout.Visible = true;
        }
        else
        {
            this.ExplicitLogin.Visible = true;
            this.ExplicitLogin.Attributes.CssStyle.Add("display", "block");
        }
    }

    protected void HandlePostback(object sender, EventArgs e)
    {
        //remove all cookies, redirect to login with current page url
        FormsAuthentication.SignOut();

        Response.Redirect(string.Format("/_layouts/Authenticate.aspx?Source={0}", HttpUtility.UrlEncode(HttpContext.Current.Request.Url.AbsoluteUri)));
    }

</script>

<SharePoint:PersonalActions AccessKey="<%$Resources:wss,personalactions_menu_ak%>"
    ToolTip="<%$Resources:wss,open_menu%>" runat="server" 
	ID="ExplicitLogout" Visible="false">
    <CustomTemplate>
        <SharePoint:FeatureMenuTemplate 
			runat="server" FeatureScope="Site" 
			Location="Microsoft.SharePoint.StandardMenu"
            GroupId="PersonalActions" ID="ID_PersonalActionMenu" UseShortId="true">
            <SharePoint:MenuItemTemplate 
				runat="server" ID="ID_PersonalInformation" 
				Text="<%$Resources:wss,personalactions_personalinformation%>"
                Description="<%$Resources:wss,personalactions_personalinformationdescription%>"
                MenuGroupId="100" Sequence="100" ImageUrl="/_layouts/images/menuprofile.gif"
                UseShortId="true" />
            <example:postbackeventmenuitem 
				runat="server" id="Example_LoginAsDifferentUser" 
				text="<%$Resources:wss,personalactions_loginasdifferentuser%>"
                description="<%$Resources:wss,personalactions_loginasdifferentuserdescription%>"
                menugroupid="200" sequence="100" useshortid="true" ononpostbackevent="HandlePostback" />
            <SharePoint:MenuItemTemplate 
				runat="server" ID="ID_RequestAccess" 
				Text="<%$Resources:wss,personalactions_requestaccess%>"
                Description="<%$Resources:wss,personalactions_requestaccessdescription%>" MenuGroupId="200"
                UseShortId="true" Sequence="200" />
            <SharePoint:MenuItemTemplate 
				runat="server" ID="ID_Logout" 
				Text="<%$Resources:wss,personalactions_logout%>"
                Description="<%$Resources:wss,personalactions_logoutdescription%>" MenuGroupId="200"
                Sequence="300" UseShortId="true" Visible="true" />           
            <SharePoint:MenuItemTemplate 
				runat="server" ID="ID_PersonalizePage" 
				Text="<%$Resources:wss,personalactions_personalizepage%>"
                Description="<%$Resources:wss,personalactions_personalizepagedescription%>" ImageUrl="/_layouts/images/menupersonalize.gif"
                ClientOnClickScript="javascript:MSOLayout_ChangeLayoutMode(true);" PermissionsString="AddDelPrivateWebParts,UpdatePersonalWebParts"
                PermissionMode="Any" MenuGroupId="300" Sequence="100" UseShortId="true" />
            <SharePoint:MenuItemTemplate 
				runat="server" ID="ID_SwitchView" MenuGroupId="300"
                Sequence="200" UseShortId="true" />
            <SharePoint:MenuItemTemplate 
				runat="server" ID="MSOMenu_RestoreDefaults" 
				Text="<%$Resources:wss,personalactions_restorepagedefaults%>"
                Description="<%$Resources:wss,personalactions_restorepagedefaultsdescription%>"
                ClientOnClickNavigateUrl="javascript:MSOWebPartPage_RestorePageDefault()" MenuGroupId="300"
                Sequence="300" UseShortId="true" />
        </SharePoint:FeatureMenuTemplate>
    </CustomTemplate>
</SharePoint:PersonalActions>
<SharePoint:ApplicationPageLink runat="server" ID="ExplicitLogin" ApplicationPageFileName="Authenticate.aspx"
    AppendCurrentPageUrl="true" Text="<%$Resources:wss,login_pagetitle%>" Style="display: none"
    Visible="false" />