user3713398 user3713398 - 1 month ago 21
ASP.NET (C#) Question

Mobile master page not automatically triggered

With my website I used to work with the two master pages created by default in any new webforms solution (i.e Site.Master & Site.Mobile.Master). I have noticed on firefox for mobile that my mobile master page never get loaded but rather the "normal" master page. With chrome for mobile or other browser everything works fine.
I made substantive changes to my solution and now the mobile master page never get loaded by default in any cases (chrome developer tools included). I have done some researches which led me to this solution that works fine with chrome but still returns false with firefox:

protected void Page_PreInit(object sender, EventArgs e)
{
if (Request.Browser.IsMobileDevice)
{
MasterPageFile = "~/Site.Mobile.Master";
}
}


The problem here is that I have to include it in every single aspx page. I have done a lot of researches and must admit that the documentation about it is quite poor.
Is not there some settings I can add to the web.config file or some code to add to my global.asax so that I don't have to check the browser in every aspx pages?

Win Win
Answer

Request.Browser.IsMobileDevice is not reliable. The following helper method could detect a little bit more.

If you want reliable detection for every device including new ones, you want to use commercial service such as 51Degrees.

protected void Page_PreInit(object sender, EventArgs e)
{
    // *** For debugging, I inverted if statement. 
   //      You can reverse it back after debugging. ****
    if (!IsMobileBrowser(HttpContext.Current))
        MasterPageFile = "~/Site.Desktop.Master";
    else
        MasterPageFile = "~/Site.Mobile.Master";    
}

public static bool IsMobileBrowser(HttpContext context)
{
    // first try built in asp.net check
    if (context.Request.Browser.IsMobileDevice)
    {
        return true;
    }

    // then try checking for the http_x_wap_profile header
    if (context.Request.ServerVariables["HTTP_X_WAP_PROFILE"] != null)
    {
        return true;
    }

    // then try checking that http_accept exists and contains wap
    if (context.Request.ServerVariables["HTTP_ACCEPT"] != null &&
        context.Request.ServerVariables["HTTP_ACCEPT"].ToLower().Contains("wap"))
    {
        return true;
    }

    // Finally check the http_user_agent header variable for any one of the following
    if (context.Request.ServerVariables["HTTP_USER_AGENT"] != null)
    {
        // List of all mobile types
        string[] mobiles =
            new[]
            {
                "android", "opera mini", "midp", "j2me", "avant", "docomo", "novarra", "palmos", "palmsource",
                "240×320", "opwv", "chtml",
                "pda", "windows ce", "mmp/", "blackberry", "mib/", "symbian", "wireless", "nokia", "hand", "mobi",
                "phone", "cdm", "up.b", "audio", "sie-", "sec-", "samsung", "htc", "mot-", "mitsu", "sagem", "sony",
                "alcatel", "lg", "eric", "vx", "nec", "philips", "mmm", "xx", "panasonic", "sharp", "wap", "sch",
                "rover", "pocket", "benq", "java", "pt", "pg", "vox", "amoi", "bird", "compal", "kg", "voda",
                "sany", "kdd", "dbt", "sendo", "sgh", "gradi", "dddi", "moto", "iphone"
            };

        // Check if the header contains that text
        var userAgent = context.Request.ServerVariables["HTTP_USER_AGENT"].ToLower();

        return mobiles.Any(userAgent.Contains);
    }

    return false;
}
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