如何让我的内容页面操作母版页上的控件？

Question

My content pages allow me to manipulate data and so, their code includes error handling blocks. What I'd like to do is set the text value for several labels in a modal window on the master page in order to display the error message to the user:

<!-- master page -->
<div runat="server" id="divModalBg" class="modalbg"> </div>
<div runat="server" id="divErrorModal" class="modal">
    <asp:Label runat="server" id="lblErrorTitle"></asp:Label>
    <asp:Label runat="server" id="lblErrorMessage"></asp:Label>
    <asp:Button runat="server" id="btnRetry" text="Retry" />
</div>

I'm not sure how I would set the values for those labels in my content page...

// Users.aspx.cs
protected void btnUpdate_Click(object sender, EventArgs e)
{
    try
    {
        // do some stuff
    }
    catch(Exception ex)
    {
        // lblErrorTitle = "Update User";
        // lblErrorMessage = String.Format("Error actioning request: [ {0} ]", ex.Message);
        // btnRetry just closes the modal (sets visible to false) so that
        // the user can try again
    }
}

So how can I access the controls on the master page so that I can do this?

I'm thinking properties on the master page, set them onPageLoad...

EDIT
As per mason 's answer below, I've done this...

// Default.master
// properties for error handling
public virtual Label ErrorTitle { get { return lblErrorAction; } }
public virtual Label ErrorMessage { get { return lblErrorMessage; } }
public virtual Panel ErrorBG { get { return pnlErrorBackground; } }
public virtual Panel ErrorModal { get { return pnlErrorModal; } }

Here's my directive:

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

And here's my code file

// Users.aspx.cs
private void deleteUser(int userid)
{
    ImajUser u = new ImajUser(userid, true);
    try
    {
        u.Delete();

        lblerr.Text = "User was deleted successfully.";
        lblerr.ForeColor = System.Drawing.Color.Green;
    }
    catch (Exception ex)
    {
        Page.Master.ErrorTitle.Text = "Delete User";
        Page.Master.ErrorMessage.Text = String.Format("Error actioning request: [ {0} ]", ex.Message);
        Page.Master.ErrorBG.Visible = true;
        Page.Master.ErrorModal.Visible = true;

    }

Now getting the following error for each of these controls:

'System.Web.UI.MasterPage' does not contain a definition for 'ErrorTitle' and no extension method 'ErrorTitle' accepting a first argument of type 'System.Web.UI.MasterPage' could be found (are you missing a using directive or an assembly reference?)

Answer 1

Although Thor's answer would work, there's a much better way. Set the master type on the content page by putting this in the ASPX file. Obviously, replace the TypeName with the name of the class from your master page's code behind.

<%@ MasterType TypeName="MyMasterClassName" %>

This makes your master page strongly typed accessible from the content page. Then, to access controls on the MasterPage (which are by default private or protected , not sure which) you'll need to use properties to expose them as public . So put this on your master page code behind...

public virtual Label LblErrorMessage { get {return lblErrorMessage;}}

Then from your code behind, you can access it like this...

Master.LblErrorMessage.Text="Hello, world!";

Answer 2

You can access any public methods in your master page using this kind of contruct:

In page.aspx:

if (Page.Master != null)
                     ((YourMasterPageType)Page.Master).SetError("your error txt");

In your master page:

public void SetError(string errMsg)
        {
            ErrCtrl.Visible = true;
            ErrCtrl.Text(errMsg);
        }