i want to pass an asp session to javascript variable-CodePudding

Ok so this is my ASP code of Login page where on success I am creating one of the session which is Session["role"]="user" and i want to pass that value to HiddenField1 and then I am trying to get this value in JavaScript but when i console.log HiddenField value I am always getting null even though I've tried almost all suggested solutions...if anyone can solve the issue then please give a way

Asp code

 if (dr.HasRows)
                {
                    if(dr.Read())
                    {
                        //Response.Write("<script> alert( 'the user  : " dr.GetValue(8).ToString() " Successfully Logged in')</script>");


                        Session["username"]=dr.GetValue(8).ToString();
                        Session["fullname"] = dr.GetValue(0).ToString();


                        Session["role"] = "user"; 


                      HiddenField1.Value = Session["role"].ToString();
                    Response.Write("<script> alert(" HiddenField1.Value ")</script>");
                        Session["status"] = dr.GetValue(10).ToString();

                    }

                    ScriptManager.RegisterStartupScript(this, GetType(), "popup", "MyAlertFunOnSucc()", true);
                   Response.Redirect("homePage.aspx");


                }

JAVASCRIPT in the masterpage Head

<script type="text/javascript">
    var array_store;
   
        array_store = document.getElementById("HiddenField1").value;
        console.log(array_store);
   
</script>

And this is my hiddenField


        <asp:HiddenField ID="HiddenField1" runat="server" />

and this the ERROR homePage.aspx:28 Uncaught TypeError: Cannot read properties of null (reading 'value')

CodePudding user response：

You can use a handler (.ashx file) for returning session value and then a ajax call in the front side to get that value , or a method with [WebMethod] attribute in backend side and a ajax call at front side to get session value.

CodePudding user response：

Ok, so you might have spend some time making it CRYSTAL clear that you have a master page here?

however, you have this code:

  HiddenField1.Value = Session["role"].ToString();
                Response.Write("<script> alert(" HiddenField1.Value ")</script>");
                    Session["status"] = dr.GetValue(10).ToString();

                }

                ScriptManager.RegisterStartupScript(this, GetType(), "popup", "MyAlertFunOnSucc()", true);
               Response.Redirect("homePage.aspx");

You do realize what a response redirect does, right? It blows out the current page, the current class, and the current controls. You then say please forget about this page, and now re-direct to a WHOLE NEW page. (home page).

So, how can you inject a script, but THEN decide to dump the whole current page not send it to the client, and THEN re-direct to a whole different page????

What this means is that you need to put/place/have that code that sets the hidden control, and the register script MOVED to the home page code. So, on home page (is PostBack = false), you can set the hidden field, and THEN do your register script.

but, with your current setup, by executing a redirect to a whole new page, your register script, and in fact even your setting of the hidden field - both make no sense at all if after setting the hidden field, and tossing in a scripts to run?

YOU THEN SAY FORGET ABOUT ALL THAT AND TRANSFER to a whole new and different page.

So, move your code that sets the hidden field, and register script to the load of the home page (page load event).