Recommendations for good ways to display user messages in asp.net?

Question

I have an app full of pages and user controls, many of which have one or more label controls on them for displaying various different messages to the user.

Example: the AddCompany.ascx user control, normally used on the Company.aspx page (with App.Master MasterPage) has a label on it called "OutOfCreditLabel" with Text="Error: You cannot create a new company, as you are out of credit". The code checks the credit and shows the label if needed.

I want to get rid of all these labels all over the place and just have a method I can call from anywhere like

ShowUserMessage("Text goes here");

In previous projects I've implemented this as a single label on the master page and public method in the .master.cs - as long as the page has the line

<%@ MasterType VirtualPath="~/App.master" %>

in it, this works - but I can't get it to work on user controls (.ascx.cs). Is there a trick to this?

Or... Is there a better way?

What would you recommend for a "global" user message method that works from anywhere in the site?

Any nice jQuery solutions, perhaps?

Update
RPM1984 has asked for further clarification, so I'm trying to ask this a different way:

I need a method I can call from the code-behind (of a page or a user control) which will then display whatever text I specify to the user, like how stackoverflow tells you about new answers to your question when you next visit the site. It can be up the top of the window (like SO) or somewhere on the page, doesn't matter. What matters is that it's a "global" approach, rather than having various javascript alerts and asp:label's littered over every other page and user control in the project.

Something like this scenario:

A user clicks the "Create Widget" button on my "widget manager" user control on my page. In the event handler is:

if (User.IsOutOfCredit)
{
    ShowUserMessage("Sorry, you cannot create widgets; you are out of credit.");
}

This results in the user seeing "Sorry, you cannot create widgets; you are out of credit." Either in a pop-up or red text in the page somewhere or at the top like StackOverflow, anything is fine

Does that make sense?

Answer 1

Why not a simple HTML "old-school" extension method? (i.e static method)

namespace Web.Helpers
{
    public class HtmlHelpers 
    {
         public static string Label(string target)
         {
              var dynamicText = SomeWhere.GetSomeCoolText();
              return String.Format("<label for='{0}'>{1}</label>", target, dynamicText);
         }
    }
}

Then in your HTML:

<%= HtmlHelpers.Label("sometarget") =>

In your main master page, just import the namespace:

<%@ Import Namespace="Web.Helpers" %>

EDIT after question updated

Ok, i see what you're trying to do now. I would recommend doing it all client-side.

That is, in your main master page, create an initially hidden <div> with a unique id:

<div id="message" style="display: none"></div>

Then create a helper method somewhere in your web project, rendering out some script.

public void DisplayMessage()
{
    string message = SomeWhere.GetSomeCoolText();
    StringBuilder script = new StringBuilder();
    script.AppendFormat("$('message').show().append("<span>{0}</span>")", message);
    Page.ClientScript.RegisterClientScriptBlock(this.GetType(), script.ToString(), true);
}

Of course, this is just a guideline. You dont have to use jQuery, you don't have to hardcode the script in the method. You could create a JavaScript function that accepts a string and modifies the HTML of the div, then just call the function.

It all depends on how complicated your "message" is, if you need special server controls, internationalization, etc.

But this is certainly the easiest way to accomplish what you want (IMHO).

Answer 2

Personally, I'd prefer using the HttpContext.Current.Items dictionary with a custom control. Similar to Keith Bluestone's approach, but doesn't require an arbitrarily named control on the page; it makes it very clear what's going on. You could package it into one class as a server control easily enough, but here it is to drop into a standard web project.

To register a message in your code behind:

SiteMessageUtility.Add("Test message");

To display in your page, or master page, or wherever, really:

<%@ Register TagPrefix="custom" TagName="SiteMessage" Src="~/Controls/SiteMessage.ascx" %>
<custom:SiteMessage runat="server" />

Here's the files you'll need:
~\App_Code\SiteMessageUtility.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

public static class SiteMessageUtility
{
    public static void Add(string message)
    {
        string currMessage = HttpContext.Current.Items["message"] as string;
        if (currMessage == null)
        {
            HttpContext.Current.Items["message"] = message;
        }
        else
        {
            HttpContext.Current.Items["message"] = currMessage + "<br/>" + message;
        }
    }
}

~\Controls\SiteMessage.aspx

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="SiteMessage.ascx.cs" Inherits="Controls_SiteMessage" %>
<asp:Literal runat="server" ID="message" />

~\Controls\SiteMessage.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Controls_SiteMessage : System.Web.UI.UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected override void OnPreRender(EventArgs e)
    {
        message.Text = (string)HttpContext.Current.Items["message"];
        base.OnPreRender(e);
    }
}

Answer 3

On the master page add the following controls: the hfMsg hidden field will hold the message that will be displayed and the hfCtrl will hold the name of the html control that will display this message which will be in this example lblMsg.

<label id="lblMsg" style="background-color:Yellow; border:solid 1px; width:200px;height:100px;display:none;"></label>    
    <asp:HiddenField ID="hfMsg" runat="server" />
    <asp:HiddenField ID="hfCtrl" runat="server" />

NOTE:you can add another html control with a different id on an ASCX control and use it to display the message instead of the lblMsg.

and the following script:

<script language="javascript" type="text/javascript">
    var msg = $('#<%= hfMsg.ClientID %>').attr("value");
    var ctrl = $('#<%= hfCtrl.ClientID %>').attr("value");

    if (msg != undefined && msg != "") {
        $("#" + ctrl).html(msg);            
        $("#" + ctrl).show();
    }
    else {
        $("#" + ctrl).hide();
    }
</script>

NOTE:the script simply checks to see if the hfMsg control has a message to display or not.

and add the following two methods to the master page:

public void ShowMessage(string control, string message)
{
    this.hfCtrl.Value = control;
    this.hfMsg.Value = message;
}

public void ClearMessage()
{
    this.hfMsg.Value = string.Empty;
}

finally you can call the ShowMessage method from any page like this to display a message on the master page:

Master.ShowMessage("lblMsg","hello world!");

and if you have a user control that holds an html label (e.g lblUserMsg) to display the message you can simply call ShowMessage and pass it the name of the label:

Master.ShowMessage("lblUserMsg","hello world!");

Answer 4

Having a SetStatus method in the MasterPage is always the way I've done this, to access the MasterPage from inside a user control, just create a private property in the usercontrol (or create a baseControl class that all user controls inherit from):

private TheNameSpaceOfMyMasterPage.MyMasterPage Master
{
     get { return (TheNameSpaceOfMyMasterPage.MyMasterPage)Page.Master; }
}

protected void btnSave_OnClick(object sender, EventArgs e)
{
     // Do your stuff... 

     // Set the Status
     this.Master.ShowStatus("blah blah blah");
}

Also if you're using a control to hold the status message remember to disable ViewState on it, otherwise you'll end up with the same status message across postbacks which you don't want.