ASP.NET C# 中的高手高手方法

Question

I am trying to do an error handling method for our company's intranet applications. The error is shown in the page with a asp:label control. When I did inline coding, it was fine, but when I try putting the code in a method on a master page, it doesn't work. I get a compilation error. Here's the method (in the master.cs file):

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

public partial class _BASE_MASTER : System.Web.UI.MasterPage
{
    public void AddError(string strWhen, string strMessage)
    {
        lblAlert.Text += "<p>" + "Une erreur s'est produite " + strWhen + "<br/>'" + strMessage + "'</p>";
        lblAlert.RenderControl(new HtmlTextWriter(Response.Output));
    }
}

No troubles yet... It works if I am in the first content page:

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

public partial class _BASE_SECTEUR_BASE : System.Web.UI.MasterPage
{
    protected void Page_Load(object sender, EventArgs e)
    {
        ((_BASE_MASTER)Master).AddError("TEST", "TEST2");
    }
}

It is wierd, it gives a small error, but it works (I wouldn't normaly use this in a load event).

It's in the second page that it doesn't work.

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

public partial class _BASE_SECTEUR_Default : System.Web.UI.Page
{
    bool errorOccured = false;
    [...]
        }
        catch (Exception e)
        {
            if (!errorOccured)
            {
                ((_BASE_MASTER)((_BASE_SECTEUR_BASE)Master).Master).AddError("lors de l'acquisition du code congé.", e.Message);
                errorOccured = true;
            }
        }
    [...]
}

'_BASE_MASTER' doesn't exists in this context, although everything seems ok. I've been trying for a couple hours now and I can't seem to find a solution. Maybe someone could help?

A couple more precisions:

I use 2 master pages:

• One to make the look of pages similar (_BASE_MASTER),
• One to make some changes (like the title) in subsections of the site(_BASE_SECTEUR_BASE).

I also checked, double-checked, triple-checked for the links between the pages. Everything works just fine without the 'AddError' method call.

Answer 1

You can do the following if you want to call a method inside master page.

// Level0 Master Page
public partial class Root : System.Web.UI.MasterPage
{
    public void AddError(string strWhen, string strMessage)
    {
        lblAlert.Text += "<p>" + "Une erreur s'est produite " + strWhen + "<br/>'" + strMessage + "'</p>";
    }
}

// Level1 Master Page
public partial class OneColumn : System.Web.UI.MasterPage
{
    public void AddError(string strWhen, string strMessage)
    {
        ((Root)Master).AddError(strWhen, strMessage);
    }
}

// Content Page
public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        ((OneColumn)Master).AddError("test", "test");
    }
}

Answer 2

I finally found a workaround. Here's my personnal solution.

/// <summary>
/// Fonctions de gestion d'erreurs personnalisées.
/// </summary>
public class ErrorHandler
{
    static string errLog = HttpContext.Current.Server.MapPath("~/Logs/errors.log");

    /// <summary>
    /// Affiche dans la page qu'une erreur s'est produite et l'indique dans un
    /// journal.
    /// Utiliser seulement si l'erreur est récupérable.
    /// </summary>
    /// <param name="strWhen">Complète la chaîne "Une erreur s'est produite ".
    /// Un "." sera ajouté après. Ex : "lors du chargement du calendrier"</param>
    /// <param name="strMessage">Le message d'erreur de l'exception. Sera encadré
    /// d'apostrophes.</param>
    static public void AddPageError(string strWhen, string strMessage)
    {
        string strPrefixe = "Une erreur s'est produite ";
        string strPage = HttpContext.Current.Request.Url.AbsolutePath;
        MasterPage mpMaster = ((Page)HttpContext.Current.Handler).Master;

        using (TextWriter errFile = new StreamWriter(errLog, true))
        {
            errFile.WriteLine(DateTime.Now.ToString() + " - (" + strPage + ") - " + strPrefixe + strWhen + " : '" + strMessage + "'");
        }

        Label lblAlert = (Label)((Page)HttpContext.Current.Handler).FindControl("lblAlert");

        // La boucle suivante sert à remonter les master page pour vérifier si un Label avec un id lblAlert existe.
        while (lblAlert == null)
        {
            if (mpMaster == null)
                return;

            lblAlert = (Label)mpMaster.FindControl("lblAlert");
            mpMaster = mpMaster.Master;
        }

        // On ne veut pas continuer si le Label n'existe pas : Des erreurs se produiraient.
        if (lblAlert == null)
            return;

        if (lblAlert.Text == "")
        {
            lblAlert.Text = "<p><i>Cliquez pour faire disparaître.</i></p>";
        }

        lblAlert.Text += "<p>" + strPrefixe + strWhen + ".<br/>'" + strMessage + "'</p>";
        lblAlert.BorderWidth = Unit.Parse("0.3em");
        lblAlert.RenderControl(new HtmlTextWriter(HttpContext.Current.Response.Output));
    }
}

Now I only have to call ErrorHandler.AddPageError("", ""); from anywhere to call my errors.