Develop Reference

ASP.NET Web Forms - Send Ajax from Page.aspx to other Different.cs/MethodName

How can I call a (static[WebMethod]) method() located inside a different page than the one calling the ajax function?
The page is also using a master page setup.
Want to call: root/Controllers/MyController.cs/method()
From: root/Pages/MyPage.aspx
Master: root/Pages/Master/MasterIndex.master
MyController inherits : Page (but doesn't have a forward .aspx view) and has this method:
[WebMethod]
public static void HelloWorld(string txt) // , string[] parameters
{
System.Diagnostics.Debug.WriteLine("HelloWorld: " + txt);
}
I've been trying this on the MyPage.aspx:
$.ajax({
url: "Controllers/MyController/HelloWorld",
type: "POST",
error: function () {
alert('error'); <-- only enters here
},
success: function () {
alert('success');
}
...
But no matter how I adjust the path with ../../, ~/, .cs, I can't seem to reach it.
This is a web forms project, but I want to have a centralized controller - and I can't convert the project to MVC.

Ok, so we don't care about controllers and what not. We using web forms, and we want to call + use a web method in another page. Sure, in fact I tend to place the required web methods in the same page - not used a "asmx" page as a result in years and years.
And you are most certainly free to consume or call webmethods you have in any page in the site.
So, the problem really comes down to getting the correct path name. But, what happens if we are a few folders down (or up) from that page? I kind of don't really want to worry, and worse yet, getting the URL path can be a pain. So, the REAL goal here is to remove that pain point, and not have to worry about the URL!!
So, I suggest this code:
<div>
<asp:TextBox ID="TextBox1" runat="server" ClientIDMode="Static"></asp:TextBox>
<br />
<asp:Button ID="Button1" runat="server"
Text="Web method call (ajax)" CssClass="btn"
OnClientClick="MyTestWeb();return false"/>
</div>
<script>
function MyTestWeb() {
tBox = $('#TextBox1')
URL = '<%: ResolveClientUrl("~/Grids/Test1.aspx/HelloWorld") %>'
alert(URL) // testing - remove when happy
$.ajax({
type: "POST",
url: URL,
dataType: "json",
contentType: "application/json; charset=utf-8",
data: "{}",
success: function (data) {
// ok, have return value, place in
// TextBox1
tBox.val(data.d)
}
});
}
So, we get the correct working URL with above. In asp.net code, you can resolve path names from the root with "~/", but such expressions don't work in JavaScript. (nor in client side controls either for that matter).
So, I use the above server side expression - it will get me the correct url each time.
For this test, my page was inside of a folder called Test4.
but, the web method page was inside of a folder called Grids.
So, the returned URL actually becomes this:
Note how we corked down one level with "..". but, really who cares what the correct URL supposed to be, I only care that I get one, and I can type in a EASY url that I know will work.
So, I suggest you try the above - and display the correct URL, then you can type that in, or just continue to the use the above idea.
The web method in that other page was this:
<WebMethod()>
Public Shared Function HelloWorld() As String
Dim str As String = "Hello world"
Return str
End Function
So, when I run the above, I get/see this:
So, at the very least, try using that server side expression to resolve the URL, pop a alert box, and see what it spits out. (but, really, you don't have to care what it spits out - as long as it works - right?).
is the static web method in the master page, or a simple aspx page? You don't have to care about the master page in this case, since you only wanting to use + consume the web method in the code behind for that given page. If the code behind (web method) is in the master page (assuming you using them), then you use the path to the master page - which would be in the root of the applcation. However, the above path name resolve suggestion will still work just fine.
So, in your case, the path name is this:
root/Controllers/MyController.cs/method()
So, in js code, then this should work:
URL = '<%: ResolveClientUrl("~/Controllers/MyController.aspx/HelloWorld") %>'

ASP.NET MVC: LogOut Heartbeat function

Basically I am looking for a reliable log out mechanism when the user closes his tab. This includes calling some server code and thus all client side only mechanisms like deleting the cookie wont work for me.
On the internet you mostly find the approach to intercept the window.unload function and then place some code in there. I know there is the possibility to filter out normal navigation requests from other events that might trigger window.unload, but I generally don't like this approach, as I have to make some sort of synchronous AJAX call in order to reliable execute some custom logout code on the server, which is definitely not the best way of achieving what I want.
There is the second approach of implementing a Heartbeat function to periodically check if the client responds. I do think this is the best approach for me / my scenario, but I am actually struggling with the implementation with ASP.NET MVC.
How would I approach this in ASP.NET MVC? I already thought of SignalR, but it's actually not directly possible to access session information within the SignalR context.

It is easy to find some fancy implementations of this (see, for instance, this question).
For a basic heartbeat implementation you will need three files: the HTML (the website page sending the beats), the controller (receiving the beats) and the JavaScript file (with your heartbeat function). You may include the JavaScript code in the HTML file, but it's better practice to keep it separated.
Here you have the exact contents of my working example:
HTML file (Heart.cshtml)
Note that you need to include both the JavaScript file and jQuery. #Url.Action("ReceiveHeartbeat", "Auxiliary") gives the address to the method (ReceiveHeartbeat) in the controller (AuxiliaryController).
<head>
<script type="text/javascript" src="~/Scripts/heartBeat.js"></script>
<script src="https://code.jquery.com/jquery-1.11.3.min.js"></script>
</head>
<body>
<script type="text/javascript">
LaunchHeartBeat('#Url.Action("ReceiveHeartbeat", "Auxiliary")');
</script>
</body>
Javascript (heartBeat.js)
Other people use setTimeout, but if you want a loop using setTimeout is cleaner. I would recommend writing two functions, using setInterval(myFunction, myInterval); (see below). You can add more stuff to the Ajax request (for instance, a success: action).
function LaunchHeartBeat(actionUrl) {
var intervalMilliseconds = 750;
setInterval(function () {
$.ajax({
type: "POST",
url: actionUrl
});
}, intervalMilliseconds);
}
Controller (AuxiliaryController.cs)
[HttpPost]
public JsonResult KeepSessionAlive()
{
// You may do stuff here
return new JsonResult { Data = "success" };
}
Edit: The alternative syntax for the Javascript file:
var actionUrl = null;
var intervalMilliseconds = 1000;
function LaunchHeartBeat(myUrl) {
actionUrl = myUrl;
setInterval(HeartBeat, intervalMilliseconds);
}
function HeartBeat() {
$.ajax({
type: "POST",
url: actionUrl
});
}

How to decide when to use Ajax vs Javascript for maintainability

During ASP.Net development i am often unsure weather i should be performing some functionality using an ajax request vs handling it all on the client with JavaScript. I often will want to use Jquery ajax functions in order to speed development up and improve maintainability even though i can achieve the same result without contacting the server.
Here is one example. In my MVC view i need to update a partial view in response to a button click. Here is a simplified version of my partial view
#foreach (Requestbox.Code.XmlContentField xmlControl in Model.RequestContentControls)
{
if (Model.IsInEditMode)
{
ViewContext.Writer.Write("<div class='editDiv'>
<a href='#' onclick='EditClick()'>Edit</a>
<a href='#' onclick='DeleteClick()'>Delete</a>");
}
switch (xmlControl.ControlType)
{
case "TextBoxField":
<div class="clearfix">
#Html.DevExpress().Label(settings => {
settings.Name = xmlControl.FieldName + "Label";
settings.AssociatedControlName = xmlControl.FieldName + "TextBox";
settings.Text = xmlControl.LabelText;
}).GetHtml()
<div class="input">
#Html.DevExpress().TextBox(settings => {
settings.Name = xmlControl.FieldName + "TextBox";
MvcExtensionHelpers.SetTextBoxSettings(settings);
settings.ControlStyle.CssClass += " full-width";
}).GetHtml()
</div>
</div>
break;
case "Header":
string header = string.Format("<{0}>{1}</{0}>", xmlControl.HeaderType,xmlControl.Value);
#Html.Raw(header)
break;
}
if (Model.IsInEditMode)
{
ViewContext.Writer.Write("</div>");
}
}
When the Edit button is clicked i need to wrap each of my sections in a div and add 2 anchor elements with onclick functions inside. I can do this by using an ajax post request and setting the Model with "IsInEditMode to true" here is the code i could call, which replaces the current partial view with the new one.
function EnableEditClick() {
$.post(rootDir + "Admin/EditClick",null,
function(partialViewResult){
$("#refTable").html(partialViewResult);
});
}
Here is the Action that could handle the ajax request
public ActionResult EditClick()
{
MyModel model = new MyModel();
model.IsInEditMode = true;
return PartialView("CustomRequest", model);
}
This is one solution, another would be to handle this all on the client by using jquery to select each of my elements that are needed and to insert the anchor elements directly. I would also be able to take some code out of the view. So something like this (Haven't tested this code but i hope you get the idea)
function EditClick()
{
var elements = $('.myTable .clearfix')
elemtns.append(' <a href='#' onclick='EditClick()'>Edit</a>
<a href='#' onclick='DeleteClick()'>Delete</a>');
}
I am torn on which will be better maintainability wise, as with the ajax way i don't have to write html in JavaScript pages and i think it will be clearer and more readable when revisting the code. However i am then using a unnecessary request to the server when i could it handle all on the client.
So my questions is should i always be doing everything on the client if possible even at the result of maintainability. Any feedback on my example is much appreciated as well.

I recommend you to use AJAX for operations, which require some background calculations on the server or to retrieve some DB data from the server. For GUI generation I would use JS, as it is quite quick, thanks to V8.
If you need to generate GUI by embedding some server data into it and this page has complex layout, I would use server side template engine.

In the example you've given, I would recommend the JS approach to control the availability of the edit and delete buttons. Or possibly a combination of the two.
When you make an Ajax call it creates a background request that causes some HTTP traffic. Unless there's some processing needed on the server to fulfil the request, then there is not much use sending that request to the server.
From looking at your code then the action you want to perform is to add two anchors to the page. This can be done easily with JS. You could even combine the two by including a partial view on your page that contains the elements you wish to include, wrapped in some markup to hide them.
You could create a partial view with the button markup.
<a href='#' onclick='EditClick()'>Edit</a>
<a href='#' onclick='DeleteClick()'>Delete</a>
And then include in your view.
<div id="buttons" style="display: none;">
#Html.Partial("_ButtonView")
</div>
Your JS would become.
function EditClick()
{
$("#buttons").toggle("display");
}
Check this JSFiddle for an example of what I mean.
In the context of this question, I would consider using an Ajax request for the actual edit action that returns a Json result with the action output. This would end up with something like.
$.ajax({ // ajax call starts
url: "YourArea/YourController/EditClick",
data: {"your data"},
dataType: 'json',
success: function(data) {
//handle json response
}
});
This Ajax request would call the controller code.
public JsonResult EditClick()
{
var myResult = Helper.Edit();
return Json(new { result = myResult });
}
Conclusion: If an event/action only affects what the user can see on the UI (i.e. controlling visibility and initiating animations) then you would probably only want to use JS/jQuery. If there's something more happening like server processing or fetching data from DB required then consider using Ajax.
In your example it seemed like the choice was between adding the elements dynamically to the page with JS or executing an Controller method via Ajax to get the elements as a partial view. I hope this answer provides a good solution for you.

What is the correct way of posting a form with jquery ajax and MVC3?

I've seen a couple of methods on how to do this. My own method that I like, except from one part, is the following:
Hijack submit-event of form
Collect the data and build a json object
var objToSend = { Property : $('#propertyField').val(), Property2 : ... };
This is the part I don't like since it's tedious to collect 25 values like this
Call $.ajax({}) and specify the url to point to an [HttpPost] enabled action somewhere
in the success: part of the ajax-query, collect the returned data (which I return as a string) and write it out where appropriate. I handle errors here as well, checking to see if the first word is "Error:" and then taking appropriate action.
I like this method apart from the collection stage. I am sure there is a better way of doing this but I'v thrown myself headlong into jquery coming from an ASP.NET WebForms-background so the whole "embrace the web" part is totally foreign to me.

You could use the serialize() method to avoid passing all the fields one by one. It will send the entire form data to the server using application/x-www-form-urlencoded content type as if it was a standard form submission:
$('#myform').submit(function() {
$.ajax({
url: this.action,
type: this.method,
data: $(this).serialize(),
success: function(result) {
// TODO: handle the success case
}
});
return false;
});
Another possibility is the jQuery form plugin:
$('#myform').ajaxForm(function(result) {
// TODO: handle the success case
});
Some people find it also useful to use the Ajax.BeginForm helpers to render the form:
#using (Ajax.BeginForm(new AjaxOptions { OnSuccess = "success" }))
{
... some input fields
}
In ASP.NET MVC 3 you need to include the jquery.unobtrusive-ajax.js script which unobtrusively AJAXifies the HTML 5 data-* attributes emitted by the Ajax helper.

Allow jQuery to build your json for you. You can serialize a form which will create a data set for you to submit.
$.post("myUrl",
$("form").serialize(),
function(callback) { ... }
);

That's how I'd do it!
You also have the option of using the MVC helpers to create the post code handling code for you if you're dealing with a form e.g.
<% using (html.BeginForm()) {%>
// html for the form
<input type='submit' value='post' />
<% } %>
The transition from WebForms to MVC can be a tricky one for people has you really are dealing with the raw aspects of web programming i.e. http, html and javascript... BTW I believe this to be a good thing as I'm not a fan of the pseudo single process event model of WebForms.
Long live MVC! :)

I tend to use the "jQuery form plugin". It allows you to cleanly abstract a standard form into an AJAX form with very little effort:
http://jquery.malsup.com/form/
It also allows you to easily trap various events, failure conditions, validations etc and can convert your form to a JSON request or XML if you desire. Handles file uploads too.

Custom Javascript Ajax for ASP.NET

I've written some basic Javascript functions and would like to learn how to enable asynchronous postbacks within a C# 4.0/ASP.net project using this JS code.
For example, I have a script that increments a number when clicked. When clicked again, the number is decremented. I basically load the number from a database, then hide one <span> and show another with the corresponding decremented number on click. This is not complicated javascript; its a simple example. Now when I click the button I want to send this increment/decrement call back to the server to update the database's number.
I realize that I can accomplish something akin to this example using the AJAX Control Toolkit's toggle button. I, however, want to know how to use my OWN javascript to create AJAX functionality.
How do I accomplish this using C# and my custom Javascript code?
I'm not opposed to using the ASP.net AJAX library, I just don't want to use a ready built control. I want to learn the process of creating my own AJAX functionality. I would presume that I will have to use an asp:UpdatePanel, but I don't know how to call C# functions from the client side.
My javascript is not jQuery, in fact I want nothing to do with jQuery until I learn more about javascript and this process.

Simple with no UpdatePanel:
First, add a Generic Handler to your project (.ashx). This will act as our Http endpoint. Our javascript will call it. We could (and probably should), use a web service endpoint but that requires processing the response and complicates the example. A handler returns plain text.
<%# WebHandler Language="C#" Class="Handler" %>
using System;
using System.Web;
public class Handler : IHttpHandler
{
// We'll use a static var as our "database".
// Feel free to add real database calls to the increment
// and decrement actions below.
static int TheNumber = 0;
public void ProcessRequest(HttpContext context)
{
string action = context.Request.QueryString["action"];
if (!string.IsNullOrEmpty(action))
{
if (action == "increment")
TheNumber++; //database update and fetch goes here
else if (action == "decrement")
TheNumber--; //database update and fetch goes here
}
context.Response.ContentType = "text/plain";
context.Response.Write(TheNumber);
}
public bool IsReusable { get { return false; } }
}
Next, create your web page and add the async javascript.
<%# Page Language="C#"%>
<html>
<head runat="server">
<script type="text/javascript">
// An XMLHttpRequest object is required to make HTTP requests.
// Try a couple instantiation strategies to handle different
// browser implementations.
function createXMLHttpRequest() {
try { return new XMLHttpRequest(); } catch (e) { }
try { return new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { }
try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) { }
alert("XMLHttpRequest not supported");
return null;
}
function callHandler(action) {
var xmlHttpReq = createXMLHttpRequest();
// We're interested in an asychronous request so we define a
// callback function to be called when the request is complete.
xmlHttpReq.onreadystatechange = function () {
if (xmlHttpReq.readyState == 4 && xmlHttpReq.status == 200)
document.getElementById("<%= lbl.ClientID%>").innerHTML
= xmlHttpReq.responseText;
}
xmlHttpReq.open("GET", "Handler.ashx?action=" + action, true);
xmlHttpReq.send(null);
}
</script>
</head>
<body>
<form id="Form1" runat="server">
<div>
The Number: <Label runat="server" id="lbl">0</Label>
</div>
<div>
<asp:Button ID="Button1" runat="server" Text="Increment"
OnClientClick="callHandler('increment');return false;" />
<asp:Button ID="Button2" runat="server" Text="Decrement"
OnClientClick="callHandler('decrement');return false;" />
</div>
</form>
</body>
</html>
The final flow is:
A web page user clicks the Increment or Decrement button which calls our javascript
Our javascript sends a request with the desired action in the querystring to Handler.ashx
Handler.ashx reads the querystring, increments or decrements its static variable, and returns the value
Our callback receives the value and updates our UI.

if your using an UpdatePanel it's very simple with a JavaScript call to __doPostBack. See here for example.

Have a look at this tutorial around AJAX
http://www.w3schools.com/Ajax/Default.Asp
It will give you an overview of using Javascript to GET and POST data using AJAX.
Hope this helps.

Here's a link on how you can incorporate ASP.NET C# with your custom Javascript code.
http://msdn.microsoft.com/en-us/library/bb386450.aspx
It also contains a sample VS 2010 project here:
http://go.microsoft.com/fwlink/?LinkId=185646
Here's generally what's going on here:
In the AjaxIScriptControl solution:
SampleTextBox.cs - takes care of rendering the script control on the page; and attachment to client javascript code (the js file)
SampleTextBox.js - takes care of client side functionality and generates Javascript object of control via prototype
Notes:
This example leverages existing
ASP.NET's built-in control (you
notice SampleTextBox inherits Textbox
and IScriptControl) but you can
render any type of HTML control if
you inherit ScriptControl class
instead.
This solution also chose to separated
the Script control code and website
code in two projects but you can
easily make it into one.
You can easily leverage another Javascript library in your JS file
In my experience so far, this is the one of the more elegant way to incorporate server side code with client side if you are to create re-useable controls for your website. You leverage server side power to do the initial rendering while provide client side capabilities through Javascript.

If you create your C# functions as WCF REST Services or older-style Script Services, then you can easily call your service methods from your JavaScript using a basic XmlHttpRequest (no jQuery or UpdatePanels needed).
Here's a quick jsFiddle I put together: http://jsfiddle.net/ndVeS/
This sample has two text boxes; you enter a value in the first one, click the button, and then that value is passed to a service (an echo service) and returned in the callback. The JavaScript code takes that value and populates the second textbox with it.
You could define a C# WCF RESTful service like this:
[ServiceContract]
public class EchoService : IEchoService {
[WebGet(UriTemplate="EchoMe?val={theValue}, ResponseFormat=WebMessageFormat.Json)]
public string EchoMe(string theValue) {
return theValue;
}
}
If you handle your calls this way, you can separate out your service logic from your presentation (ASPX files), and this allows for easier testing and you can also separate responsibilities from those who build the UI from those that build the business functionality.
I have to admit I'm more of a jQuery person when it comes to this, but I thought it's a great exercise to figure out how the XmlHttpRequest works under the hood. It makes you appreciate what jQuery (or similar framework) provides.
Here's a nice overview of the XmlHttpRequest object and how to use it: http://www.jibbering.com/2002/4/httprequest.html
I hope this helps.

function GetXmlHttpObject(handler) {
var objXMLHttp = null
if (window.XMLHttpRequest) {
objXMLHttp = new XMLHttpRequest()
}
else if (window.ActiveXObject) {
objXMLHttp = new ActiveXObject("Microsoft.XMLHTTP")
}
return objXMLHttp;
}
function GetDropDown() {
function stateChanged(StatesUpdated) {
if (xmlHttp.readyState == 4 || xmlHttp.readyState == "complete") {
document.getElementById('updateplace').innerHTML = xmlHttp.responseText;
//"updateplace" is you div id which will hold the new data or new page
if (navigator.appName != "Microsoft Internet Explorer") {
}
}
else {
//alert(xmlHttp.status);
}
}
xmlHttp = GetXmlHttpObject()
if (xmlHttp == null) {
alert("Browser does not support HTTP Request");
return;
}
url = "xyz.aspx" //this might be sent to any post data
url = url + "&sid=" + Math.random();
xmlHttp.onreadystatechange = stateChanged;
xmlHttp.open("GET", url, true);
xmlHttp.send(null);
}
with the above code you can send data to any .cs file also where you can change the data and load it in a new page which will load in the update div and the method should redirect to the new aspx file.
I hope you got the logic :)
if you have any doubts reach me # sankalpa.sam#gmail.com

I know it's not MVC that you're doing, but have a look at the MVC section of the ASP.NET site and you will find a lot of examples of AJAX calls there - MVC doesn't use those dreadful script-soup creating .NET objects. Most will probably be using jQuery - this is an open-source javascript library that can plug into any web app and provides some really nice functionality.

Maybe u r looking for this:
function ajaxscript(){
$.ajax({
type: "POST",
url: |url/methodName|,
data: |variable_name|,
contentType: "application/json; charset=utf-8",
dataType: "json",
success: |some javascript here|,
error: |some javascript here|
});