how to create message box in public static void method

Question

I have a public static method and I would like a message to be displayed if certain values are selected. This is in ASP.NET so adding using System.Windows.Forms; causes problems because I am using using System.Web.UI.WebControls;. So how do I create a message?

public static void UpdateSerialQtyRcvd(int SerNoID, int QtyRcvd)
{
     if (SerNo.QtyRcvd != 1)
     {
         if (SerNo.Reason == "")
         {
             //message
         }
     }
}

Javascript behing the code:

function UpdateSerialQtyRcvd(sender, SerNoID, QtyRcvd) {
        if (QtyRcvd < 0) {
            alert("Qty Rcvd must be greater than 0");
        }
        else {
            PageMethods.UpdateSerialQtyRcvdUserControl(SerNoID, QtyRcvd, OnUpdateSuccess, OnUpdateFail);
        }
}

Calling the web method:

[WebMethod]
public static void UpdateSerialQtyRcvdUserControl(int SerNoID, int QtyRcvd)
{
     JobDeliveryDebrief.UpdateSerialQtyRcvd(SerNoID, QtyRcvd);
}

Answer 1

This method show a message. The UpdateSerialQtyRcvd is in a WebUserControl.ascx as you want:

public static void UpdateSerialQtyRcvd(System.Web.UI.Page pg)
{
     pg.ClientScript.RegisterStartupScript(pg.GetType(), "alert", "<script>alert('Message');</script>");
}

Now you can add your if-statement like this:

public static void UpdateSerialQtyRcvd(System.Web.UI.Page pg, int qtyRcvd)
{
     if (qtyRcvd != 1)
     {
          //if (SerNo.Reason == "")
          //{
                pg.ClientScript.RegisterStartupScript(pg.GetType(), "alert", "<script>alert('Message');</script>");
          //}
     }
}

Now you can call to UpdateSerialQtyRcvd static method from every page that has registered the WebUserControl.ascx. like this:

YourPage.aspx:

<%@ Register Src="~/WebUserControl2.ascx" TagPrefix="uc1" TagName="WebUserControl2" %>
<uc1:WebUserControl2 runat="server" id="WebUserControl2" />

YourPage.aspx.cs:

protected void Page_Load(object sender, EventArgs e)
{
    WebUserControl2.UpdateSerialQtyRcvd(this,2);
}

Answer 2

Add a JavaScript alert:

clientscriptmanager.registerstartupscript(this.GetType(),"MyAlert","<script>alert('Hello');</script>",true);

To use ClientScript inside a static method pass the Page object as a parameter to your static method.Page is not static class.You can not call non static fields inside static method.So you need to pass the page object to your static method as a parameter.

protected void Page_Load(object sender, EventArgs e)
{
     UpdateSerialQtyRcvd(SerNoID, QtyRcvd,Page);
}

public static void UpdateSerialQtyRcvd(int SerNoID, int QtyRcvd,Page page)
{
    if (SerNo.QtyRcvd != 1)
    {
        if (SerNo.Reason == "")
        {
            page.ClientScript.RegisterStartupScript(page.GetType(),"alert", "<script>alert('Hai');</script>");
        }
    }        
}