Call Code Behind Function from JavaScript (not AJAX!)

Question

I have a function on my server side.

protected void SelectParticipant(string CompanyId, string EmployeeNumber)
{
    //I do some stuff here.
}

I want to call this function from JavaScript on the client side. I've tried searching for it, but all the suggestions I found were for calling a Page Method via AJAX. I don't want that, I want to cause a postback.

function MyJSFunction(companyid, employeenumber)
{
    //cause postback and pass the companyid and employee number
    //this is where I need help!
}

How can I cause a postback and run a server side function from my JavaScript?

Tinwor · Accepted Answer · 2014-04-04 15:00:30Z

1

You can solve your problem using two HiddenField.

Set the two HiddenField using js/jquery(as you prefer)
Force the form submit in the js function(form1.submit())
In the formLoad check if the HiddenFields are empty. If no run your method and then clear the HiddenFields

answered Apr 4, 2014 at 15:00

Tinwor

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1 Comment

mason Over a year ago

+1 Thanks, the solution I used was similar in concept to this.

Issac · Accepted Answer · 2014-04-04 15:23:38Z

1

You can use the __doPostBack function to post to server. just make sure you add a server control to the page so the function is inserted. here is a small example that you can customize for your needs:

aspx:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="Try1.WebForm1" EnableEventValidation="false"%>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script src="Scripts/jquery-1.10.2.min.js"></script>
    <script type="text/javascript">
        $(document).ready(function () {
            $('#lblInvoke').hover(
                function () {
                    __doPostBack('<%= LinkButton1.ClientID %>', 'value1,value2');
                     }
                );
             });
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <label id="lblInvoke">Hover This!</label>
        <br />
        <asp:LinkButton ID="LinkButton1" runat="server" OnClick="LinkButton1_Click" Style="display:none;">LinkButton</asp:LinkButton>
        <asp:Label ID="Label1" runat="server" Text=""></asp:Label>
    </div>

    </form>
</body>
</html>

code behind:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace Try1
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }
        protected void LinkButton1_Click(object sender, EventArgs e)
        {
            string passedArgument = Request.Params.Get("__EVENTARGUMENT");
            string[] paramsArray = passedArgument.Split(',');
            Label1.Text = string.Format("Returned from server. params: {0},{1}", paramsArray[0], paramsArray[1]);
        }
    }
}

Make sure you add the EnableEventValidation="false" attribute to page.

answered Apr 4, 2014 at 15:23

Issac

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2 Comments

mason Over a year ago

+1 I managed to figure this out a few minutes before you posted it. I did have one improvement: I pass the arguments as a JSON object to avoid needing to parse a string.

Issac Over a year ago

I saw you did the minute I posted myself...the JSON stuff is sure more elegant.

mason · Accepted Answer · 2015-02-10 03:30:48Z

Here's how I did it...

<script type="text/javascript">
function AddParticipant(companyid, employeenumber)
    {
        $("#AddParticipantPanel").dialog("close");
        var myargs = {CompanyId: companyid, EmployeeNumber: employeenumber};
        var myargs_json = JSON.stringify(myargs);
        __doPostBack('<%= SelectParticipantBtn.UniqueID %>', myargs_json);
    }
</script>
<asp:Button runat="server" ID="SelectParticipantBtn" ClientIDMode="Static" OnClick="SelectParticipantBtn_Click" style="display:none;" />

And on the server side...

/* this is an inner class */
public class SelectParticipantEventArgs
{
    public string CompanyId {get; set;}
    public string EmployeeNumber {get; set;}
}
protected void SelectParticipantBtn_Click(object sender, EventArgs e)
{   
    string args = Request.Form["__EVENTARGUMENT"];
    var myargs = JsonConvert.DeserializeObject<SelectParticipantEventArgs>(args);
    string emp_no = myargs.EmployeeNumber;
    string company_id = myargs.CompanyId;
    //do stuff with my arguments
}

Instead of using HiddenFields, I used a hidden button. This model works better because I can go directly to the button's event handler instead of having to add code to the Page_Load function.

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