从Usercontrol.ascx javascript调用Usercontrol.cs中的Webmethod

Question

I have a usercontrol and in that I have a javascript function which makes a call to webmethod.

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="LeftMenu.ascx.cs"
Inherits="UserControls_LeftMenu" %>

<script type="text/javascript">

function GetRealTimeCount() {
    PageMethods.CountOfMenus('', '', GetCountOfMenus_Success, GetCountOfMenus_Fail);
}

My webmethod code is

[System.Web.Services.WebMethod]
public static string CountOfMenus(string StartDate, string EndDate)
{
    //Code here
}

But when I run the code, it gives me javascript error, CountOfMenus is undefined . I know the error is because it cant find the method in the current page but I want it to access method in the usercontrol.cs. I cant write the webmethod in every page as I have lots of pages where the usercontrol is used. Is there any way through which I can call the method of usercontrol.cs in javascript?

Answer 1

I solved this by below method

Javascript :

function GetRealTimeCount(StartDate, EndDate) {
    var xmlhttp;
    if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari
        xmlhttp = new XMLHttpRequest();
    }
    else {// code for IE6, IE5
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    var url = "Default.aspx?Method=CountOfMenus&SD=" + StartDate + "&ED=" + EndDate;
    xmlhttp.open("Get", url, false);
    xmlhttp.send(null);
    document.getElementById("Count").innerHTML = xmlhttp.responseText;
}

Code Behind:

protected void Page_Load(object sender, EventArgs e)
{
    if (Request.QueryString["Method"] == "CountOfMenus")
        {
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            GetCount(Request.QueryString["SD"], Request.QueryString["ED"]);
        }
    }

    private void GetCount(string StartDate, string EndDate)
    {
        Response.Clear();

        // Code to get count

        Response.Write(Count.ToString());
        Response.End();
    }

The below link from where I got these solutions has many other options to call C# methods from javascript

http://www.morgantechspace.com/2014/01/Call-Server-Side-function-from-JavaScript-in-ASP-NET.html

Answer 2

when your JS code calls a PageMethod using "PageMethods." , the call does not reach the page method if it was defined in the control. The page methods in the page are only callable.

I suggest another approach, using Http Handler which is also efficient. Try follow this post:

Call HttpHandler from javascript

Also, the following post might be useful:

http://www.undisciplinedbytes.com/2010/03/ajax-call-using-an-asp-net-http-handler/

Answer 3

Do you have ScriptManager in your UserControl Page? if not you have to add it and set EnablePageMethods="true"

 <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="true">
        </asp:ScriptManager>