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cannot get the session on vb page when it set using jquery

I have a img button. When it is clicked, I set the session value using jquery. however I cannot get the session on vb code behind. My process is like that after the user click the image, I set the session. When the user open popup page and return the page. I need to check the session to do something. However in the vb code, the session is nothing. Would some one tell me how to do it.
The below code call the function:
<asp:Image ID="img" runat="server" onclick="SetSession(hdID);" ImageUrl="pic_bottle.gif" />
The jquery script:
function SetSession(hdID) {
var hd = $('#' + hdID);
var hdValue = hd.val();
if (hdValue == "s") {
$.session.set('UpdateProdOrder', -1);
}
else {
var hdProdID = $('#hdProdID').val();
$.session.set("UpdateProdOrder", hdProdID);
}
alert($.session.get("UpdateProdOrder"));
}
The vb code behind never get the session
If Not Session("UpdateProdOrder") Is Nothing Then
'do something
updateOrder()
end if

The localStorage and sessionStorage properties allow saving key/value pairs in a web browser.
The sessionStorage object stores data for only one session (the data is deleted when the browser tab is closed).
These values are maintained on the client side, but you are trying to retrieve it on the server side. session variables are server side
Solution:
Method 1:
You'd have to have a little ajax call to talk to the server to set it.
please check it out
Method 2 :
Assigning the ASP.NET Session Variable using Javascript.
<script type="text/javascript">
function SetSession(hdID)
{
var hd = $('#' + hdID);
var hdValue = hd.val();
if (hdValue == "s") {
'<%Session["UpdateProdOrder"] = "' + -1+ '"; %>';
}
else {
var hdProdID = $('#hdProdID').val();
'<%Session["UpdateProdOrder"] = "' + hdProdID+ '"; %>';
}
alert('<%=Session["UpdateProdOrder"] %>');
}
</script>
Accessing ASP.NET Session variable using Javascript:
<script type="text/javascript">
function GetSession()
{
var updateProdOrder= '<%= Session["UpdateProdOrder"] %>';
alert(updateProdOrder);
}
</script>

You cannot change a server side Session object with javascript directly. You need to send it to the server somehow. This can be done by changing the image to an ImageButton and do a PostBack to modify the Session object. But since you seem to have some data in hdID. You cannot send that to the server with a ImageButton alone, you'll need a HiddenField
<asp:ImageButton ID="ImageButton1" runat="server" OnClientClick="SetSession(hdID);"
ImageUrl="pic_bottle.gif" OnClick="ImageButton1_Click" />
<asp:HiddenField ID="HiddenField1" runat="server" />
<script type="text/javascript">
var hdID = 'test';
function SetSession(hdID) {
$('#<%= HiddenField1.ClientID %>').val(hdID);
}
</script>
And then in code behind
protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
{
Session["UpdateProdOrder"] = HiddenField1.Value;
Label1.Text = string.Format("Session value is now '{0}'", Session["UpdateProdOrder"]);
}
You could do this also without the javascript SetSession, but that depends on where and when hdID is used on other parts of the page.

How to access ImageButton control from another class?

JS Code:
<script type="text/javascript">
function ShowCurrentTime(name) {
PageMethods.GetCurrentTime(name, OnSuccess);
}
function OnSuccess(response, userContext, methodName) {
alert(response);
}
</script>
HTML Code:
<asp:ImageButton ID="IMGBTN001" runat="server" ImageUrl="Images/ico/labaniat.png"
class="img-responsive em-img-lazy" OnClientClick="ShowCurrentTime('01')" />
<asp:Image class="img-responsive retina-img em-img-lazy" ID="IMGMostViewed" runat="server"ImageUrl="Images/Banner/block1_banner.jpg" />
Code Behind C#
[System.Web.Services.WebMethod]
public static string GetCurrentTime(string name)
{
//string x = IMGMostViewed.ImageUrl;
return "Hello " + name + Environment.NewLine + "The Current Time is: "
+ DateTime.Now.ToString();
}
I want to access the Image from another class.
How can I access the IMGMostViewed this GetCurrentTime class?
i used this code, but get "page.FindControl("IMGMostViewed")" return null
[System.Web.Services.WebMethod]
public static string GetCurrentTime(string name)
{
if (HttpContext.Current != null)
{
Page page = (Page)HttpContext.Current.Handler;
Image IMGMostViewed = (Image)page.FindControl("IMGMostViewed");
string x = IMGMostViewed.ImageUrl;
}
return "Hello " + name + Environment.NewLine + "The Current Time is: "
+ DateTime.Now.ToString();
}

Theoreticaly you can cast the CurrentHandler to your type of page and then access your button:
var currentHandler = HttpContext.Current.CurrentHandler as T;
currentHandler.IMGBTN001.ImageUrl = "abc";
The beter way would be to access your button on clientside in your success function.
function ShowCurrentTime(name) {
PageMethods.GetCurrentTime(name, OnSuccess);
}
function OnSuccess(response, userContext, methodName) {
//Access here your button and modify it
}
Here you also will find a related Answer:
How to access page controls inside a static web method?

Getting a framework to deal with knockout.js not persisting via hidden field

VS2013, WebForms, .NET 4.51
I want to use a hidden field to maintain the contents of my Knock Out view model across postbacks. So I took the KO code from http://knockoutjs.com/examples/cartEditor.html and then read http://www.codeproject.com/Articles/153735/Using-KnockoutJS-in-your-ASP-NET-applications for some ideas.
The end result is the following:
<asp:HiddenField ID="HiddenField1" runat="server" />
<script type='text/javascript' src="http://knockoutjs.com/examples/resources/sampleProductCategories.js"></script>
<script type="text/javascript">
function formatCurrency(value) {
return "$" + value.toFixed(2);
}
var CartLine = function () {
var self = this;
self.category = ko.observable();
self.product = ko.observable();
self.quantity = ko.observable(1);
self.subtotal = ko.computed(function () {
return self.product() ? self.product().price * parseInt("0" + self.quantity(), 10) : 0;
});
// Whenever the category changes, reset the product selection
self.category.subscribe(function () {
self.product(undefined);
});
};
var Cart = function () {
// Stores an array of lines, and from these, can work out the grandTotal
var self = this;
self.lines = ko.observableArray([new CartLine()]); // Put one line in by default
self.grandTotal = ko.computed(function () {
var total = 0;
$.each(self.lines(), function () { total += this.subtotal() })
return total;
});
// Operations
self.addLine = function() {
self.lines.push(new CartLine());
SaveList();
};
self.removeLine = function(line) {
self.lines.remove(line);
SaveList();
};
self.save = function () {
var dataToSave = $.map(self.lines(), function (line) {
return line.product() ? {
productName: line.product().name,
quantity: line.quantity()
} : undefined
});
alert("Could now send this to server: " + JSON.stringify(dataToSave));
};
self.SaveList = function () {
var myHidden = document.getElementById('<%= HiddenField1.ClientID %>');
if (myHidden)//checking whether it is found on DOM, but not necessary
{
var dataToSave = $.map(self.lines(), function (line) {
return line.product() ? {
productName: line.product().name,
quantity: line.quantity()
} : undefined;
});
alert("Saving - " + JSON.stringify(dataToSave));
myHidden.value = JSON.stringify(dataToSave);
}
};
};
var stringViewModel = document.getElementById('<%=HiddenField1.ClientID %>').value;
var viewModel;
if (document.getElementById('<%=HiddenField1.ClientID %>').value == '') {
alert('Nothing In Hidden Field');
viewModel = new Cart();
} else {
viewModel = ko.utils.parseJson(stringViewModel);
for (var propertyName in viewModel) {
viewModel[propertyName] = ko.observable(viewModel[propertyName]);
}
}
ko.applyBindings(viewModel);
$(document.forms[0]).submit(function () {
alert('In Submit');
viewModel.SaveList();
});
</script>
So basically when the page loads we create a new instance of the Cart. And when the form is posted we successfully have the cart serialized to HiddenField1 and I can see the expected value in the code behind:
protected void btnSave_OnClick(object aSender, EventArgs aE)
{
if (HiddenField1.Value == null)
{
}
}
however after the postback the contents of stringViewModel
var stringViewModel = document.getElementById('<%=HiddenField1.ClientID %>').value;
is always blanl / empty? Why is that?
And then assuming I have the correct JSON is the following the correct way to apply it back to the view model?
viewModel = ko.utils.parseJson(stringViewModel);
for (var propertyName in viewModel) {
viewModel[propertyName] = ko.observable(viewModel[propertyName]);
}
EDIT: I tried a few things with no luck
Added all JS code to jQuert OnReady() handler
Tried using instead of ASP:HiddenField
In all cases in PostBack I can see the value assigned to the hidden field by SaveList(), but when the page is displayed again (after postback) the value of the hidden field is an empty string

For the first part, what you're doing is correct. Use the console (press F12 in your browser) to examine the hidden field, and check if it has the value. If you see it in the server side, it should be in the client side. You can also run js code, and set breakpoints to discover what the problem is. You can also add a PreRender handler in the server side, and add a breakpoint and debug to check that the Value has not been deleted in the server side (this event happens just before the page is rendered to be sent to the browser).
For the second part, the fastest way to do what you need is to use knockout mapping, which creates a model from a JavaScript object, or from JSON. You need to use this: ko.mapping.fromJSON. This will create a new viewmodel, which you can directly bind, from your JSON. (As you can read in the docs, you can customize how the view model is created).
However, what you're doing is quite strange. You normally use Knockout with Web API, or Web Services, or Page methods, without reloading the page. The model is recovered, and updated, changed, etc. through one of those technologies, using AJAX.

Calling Jquery function from .Net, with parameters

I have a .Net method which does some validation on an object, and then, I need to display the issues to the user.
I am trying to use a jquery message box I found:
The jquery function:
function ShowPopup() {
$.msgBox({
title: "Unable to save",
content: "An error has occured while saving the object."
});
}
I need to call that from a .Net method, passing it a List of strings. Is that possible? And then set the content property to be the list of errors?
My .Net saving method, which may trigger this popup, looks like this:
protected void btnSave_Click(object sender, EventArgs e)
{
var o = new UserDto
{
DisplayName = txtName.Text,
Email = txtEmail.Text,
Username = txtUsername.Text,
Password = txtPassword.Text,
TimeZoneId = ddZones.SelectedValue,
Id = Session["SelectedUserId"] == null ? 0 : int.Parse(Session["SelectedUserId"].ToString())
};
var result = new UserService(Common.CurrentUserId()).SaveUser(o);
if (result.Success == false)
{
// Show an error.
return;
}
Response.Redirect("users.aspx");
}
If success is false, I want to pass it a list of errors, and show that popup.
The jQuery function is from here.

Try this
if (result.Success == false)
{
// Show an error.
ScriptManager.RegisterStartupScript(Page, Page.GetType(), "close", "ShowPopup(parm1,parm2);", true);
return;
}
Hope it will helps you

You can use ClientScriptManager http://msdn.microsoft.com/es-es/library/asz8zsxy.aspx to inject your javascript into the page.
protected void btnSave_Click(object sender, EventArgs e)
{
var o = new UserDto
{
DisplayName = txtName.Text,
Email = txtEmail.Text,
Username = txtUsername.Text,
Password = txtPassword.Text,
TimeZoneId = ddZones.SelectedValue,
Id = Session["SelectedUserId"] == null ? 0 : int.Parse(Session["SelectedUserId"].ToString())
};
var result = new UserService(Common.CurrentUserId()).SaveUser(o);
if (result.Success == false)
{
// Define the name and type of the client scripts on the page.
String csname1 = "MessageBoxScript";
Type cstype = this.GetType();
// Get a ClientScriptManager reference from the Page class.
ClientScriptManager cs = Page.ClientScript;
// Check to see if the startup script is already registered.
if (!cs.IsStartupScriptRegistered(cstype, csname1))
{
StringBuilder cstext1 = new StringBuilder();
cstext1.Append("<script type=text/javascript> $.msgBox({title: 'Unable to save',content: 'An error has occured while saving the object.'}); </");
cstext1.Append("script>");
cs.RegisterStartupScript(cstype, csname1, cstext1.ToString());
}
return;
}
Response.Redirect("users.aspx");
}
Another option is to save your errors in a session variable like:
C#
Session["Errors"] = "My errors";
Javascript:
var errors = '<%=Session["errors"]%>';
if(errors){
$.msgBox({
title: "Unable to save",
content: errors
});
}

I'm assuming that your btn_Save method fires in response to a client event, such as the user clicking the Save button. I'm also assuming you're using MVC. If that's the case, then the best way to accomplish what you're looking for is to make the Save button on the client fire a $.click event. In the click event, you call your MVC controller Save method using ajax. This way, the Save method can return JSON from the server, and you can display the returned messages on the client. Something like this:
Server:
[HttpPost]
public ActionResult Save(object myData)
{
return Json(new {message="Hello World"});
}
Client:
$('#saveBtn').click(function()
{
$.post('#Url.Action("Save")',
{myData: data},
function(result){
if (result){
showPopup(result);
}
}
)
})

you can call your jQuery method with ScriptManager this way :
if (result.Success == false)
{
ScriptManager.RegisterStartupScript(this.Page, this.GetType(), "tmp", "<script type='text/javascript'>ShowPopup();</script>", false);
return;
}

calling a serverside method in a javascript function?

Here i am calling a javascript function on a button click and i need to call the server side method inside the javascript function after finishing its execution.
Javascript Function
function exportCharts(exportFormat) {
initiateExport = true;
for (var chartRef in FusionCharts.items) {
if (FusionCharts.items[chartRef].exportChart) {
document.getElementById("linkToExportedFile").innerHTML = "Exporting...";
FusionCharts.items[chartRef].exportChart({ "exportFormat": exportFormat });
}
else {
document.getElementById("linkToExportedFile").innerHTML = "Please wait till the chart completes rendering...";
}
}
}
Server side Method
protected void imgBTNExportPPT_Click(object sender, ImageClickEventArgs e)
{
try
{
PredictExportToPPT objOExporttoPPT = new PredictExportToPPT();
PredictionModel();
string reportNames = ObjCommon.GetBIReportNames("Prediction", "Report");
reportNames += ObjCommon.GetBIReportNames("Prediction", "Table");
objOExporttoPPT.ExportToPPTPredict(ObjPredictInputParameter, reportNames, ObjSharedEntities.PredictTableData);
string itemname = "PPTOutput.pptx";
HttpContext.Current.Response.Clear();
HttpContext.Current.Response.ContentType = "pptx";
HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + itemname + "");
HttpContext.Current.Response.BinaryWrite(System.IO.File.ReadAllBytes(HttpContext.Current.Server.MapPath(DataTemplate.PPTOutputTemplateFilePath)));
HttpContext.Current.Response.Flush();
HttpContext.Current.Response.End();
}
catch (Exception exceptionMessage)
{
throw (exceptionMessage);
}
finally
{
GC.Collect();
}
}
and i have tried like this
$(document).ready(function () {
$("#imgBTNExportPPT").click(function (e) {
e.imgBTNExportPPT_Click();
$.ajax({
type: "POST",
url: "PEventPerformance.aspx/updateContent",
data: "{}",
success: function (result) {
}
});
});
});
Any suggestion??

Your imgBTNExportPPT_Click looks like an click event of a button. You may try the following to raise the event from JavaScript
Place this javascript in aspx page
<script type="text/javascript">
function myfunc() {
<%= Page.ClientScript.GetPostBackEventReference(imgBTNExportPPT, String.Empty) %>;
}
</script>
Call this function against OnClientClick
<asp:Button ID="Button1" runat="server" Text="Button" OnClientClick="myfunc();" />
This will fire the server side event:
protected void imgBTNExportPPT_Click(object sender, ImageClickEventArgs e)
{
}

You can use Ajaxpro for this purpose, If u want to generate a server side call without any event like button click.
In Your code behind file. Under the Page_Load section add
AjaxPro.Utility.RegisterTypeForAjax(typeof(YourCodebehindfilename));
In client side
call the server side method like
var content = YourCodeBehind.Yourmethod(optional parameters).value;
In content you can get your response as an object and can do further changes

I guess the best way to execute server side method is to use Web Services.
You have to write a Web Service that that contains your server side method.Then you can call it using AJAX.