page_load event in Master and Content Pages

问题

Here is the sequence in which events occur when a master page is merged with a content page:

http://msdn.microsoft.com/en-us/library/dct97kc3.aspx

So, my problem is:

I have one login page (not use master page), one master page, and hundreds of content page.

I check login session Session["loggedInUser"] in master page (if not logged in, redirect to login page)

So, when I don't log in, if I type the address of one content page, it must check login session in master page and redirect to login page, right? But it has two cases here:

If in content page, I don't use anything related to Session["loggedInUser"], it will redirect to login page, so, it's OK here!

The second case: if I use Session["loggedInUser"] to display Username in content page for example:

UserInfo loggedInUser = (UserInfo)Session["loggedInUser"];

it will return null object here, because the page_load in content page is fired before page_load in master page, so it thows null object instead of redirecting to login page.

I also tried Page_PreInit in master page but no help

protected void Page_PreInit(object sender, EventArgs e)
{
    if (Session["loggedInUser"] == null)
    {
        Response.Redirect("~/Login.aspx");
    }
}

Any suggestion?

回答1:

Presumably, when you say you are using the Session["loggedInUser"] value, you are then calling .ToString() method or similar to display it?

In which case, you will need to check for a null object before using it. It would be best practice to check for the existance of the object before using any methods on it in any case, so:

if (Session["loggedInUser"] != null)
{ ... }

Only if you are certain that the code will never be executed without the Session object being instantiated can you use methods without checking for a null reference.

http://msdn.microsoft.com/en-us/library/03sekbw5.aspx

回答2:

Finally I've come up with a solution:

I create a class BasePage like this:

public class BasePage : System.Web.UI.Page
{
    protected override void OnLoad(EventArgs e)
    {
        if (Session["loggedInUser"] == null)
        {
            Response.Redirect("~/Login.aspx");
        }
        base.OnLoad(e);
    }
}

And in the content page, instead of inheriting from Page, I change to BasePage and it works perfectly

Thanks for all of your support

Nice day ;)

回答3:

You could check for Session["loggedInUser"] in the content Page's Page_PreRender() rather than Page_Load()or alternatively, do the master page check in the Page_Init() rather than Page_Load(). We had the same problem and went with the Master page Page_Init() option, so that we could still use Page_Load() in all the Content pages.

Edit: It's Page_Init() not PreInit().

回答4:

I have 2 masterpages(1 for prelogin,2nd for afterlogin),home page is independent,logout page inherits postlogin page) in all postloginpage session chck if sessionnull(xyz)else(redirect loginpage) all this in Page_Init event of afterlogin.master................Successfull

来源：https://stackoverflow.com/questions/5933929/page-load-event-in-master-and-content-pages

标签

ASP.NET

master-pages

content-pages