I am just learning how to use TCP client server relationships. I have been looking for hours and hours but I do not see any way that a Client can get input from the user and then the client sent a byte[] array to the server and have it do anything but compare strings, is there some way that I can have it call a method with this input? or am I missing something?
I have heard of something called serialization, though there seem to be several ways to use it, can someone point me in the right direction if this is correct?
Thanks for any reply
For a basic .NET website, I like to use the page methods for a quick easy way to make client to server calls. Consider the following aspx page and its code behind. You can expose public static server methods to javascript by adding the [WebMethod] attribute. Then you can call the function from javascript using PageMethods.NameOfFunction(). Just make sure you have a scriptmanager on the aspx page with the EnablePageMethods property set to "true".
Default.aspx
<%# Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script type="text/javascript">
function init() {
var str = "bytes";
var data = [];
for (var i = 0; i < str.length; ++i)
{
data.push(str.charCodeAt(i));
data.push(0);
}
PageMethods.DoSomething(data);
}
</script>
</head>
<body onload="init();">
<form id="form1" runat="server">
<asp:ScriptManager ID="ScriptMan" runat="server" EnablePageMethods="true">
</asp:ScriptManager>
</form>
</body>
</html>
Default.aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml.Linq;
using System.Web.Services;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
[WebMethod]
public static void DoSomething(byte[] data)
{
//Do something with data from javascript
}
}
Related
I've been doing some really clever stuff (I think) in ASP.Net c#, so much so that the simple stuff is more difficult (if that makes sense)
I have this snippet of code in my page
<form id="form1" runat="server">
<asp:HiddenField runat="server" ID="hdnConfirm" value="Hello World" />
<asp:LinkButton runat="server" PostBackUrl="/confirm.aspx" Text="Confirm">
</asp:LinkButton>
</form>
I have this snippet of code in confirm.aspx.
if !(IsPostback)
{
lblConfirm.Text = Request.Form["hdnConfirm"]
}
I was expecting this to be nice and simple but when i click the button and go to page "confirm.aspx" the Request.Form has no values. What have I missed ?
[TESTING]
I ran a test on a brand new web forms project in VS2013. Dot.Net 4.5.1 This does not work. PreviouPage is always null. Whether surrounded by (!IsPostBack) or not. Doesn't matter if the submitting control is a Button, LinkButton or Hyperlink. Request.Form["hdn"] is also null. I have restarted my computer just in case and still no joy. I am missing something really simple I am sure of it but I can't see what
This is the first page nothing in the code behind
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication2.WebForm1" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:LinkButton runat="server" PostBackUrl="~/WebForm2.aspx">click</asp:LinkButton>
<asp:HiddenField runat="server" ID="hdn" Value="3" />
</div>
</form>
</body>
</html>
This is the second page
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm2.aspx.cs" Inherits="WebApplication2.WebForm2" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
</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 WebApplication2
{
public partial class WebForm2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string s = ((HiddenField)this.PreviousPage.FindControl("hdn")).Value;
}
}
}
On confirm.aspx use PreviousPage.FindControl instead :
HiddenField hdnFieldName = this.PreviousPage.FindControl("hdnConfirm") as HiddenField;
string hiddenValue = string.Empty;
if (hdnFieldName != null)
{
hiddenValue = hdnFieldName.Value;
}
Here is good example to get you started.
What's going on Here:
By default with VS 2013 and Asp.Net v4.5.1 , there is a feature FriendlyUrls which is enabled.
The FriendlyUrls feature does kind of Asp.Net routing , thus changing URLs from localhost/webform1.aspx to localhost/webfrom1
PostbackUrl property will not work in combination with Asp.Net Routing. When ASP.NET routing is in use the PreviousPage URL is the final routed URL. The runtime will check for a file represented by the Routed URL now, which will be webform1 and NOT webfrom1.aspx. Since there is NO such file as webform1, so it will always set the PreviousPage to null.
Possible Solutions:
So, now you know the issue at hand.
1.) Either don't use the Routing system of Asp.Net Friendly Urls , in this case, therefore try adding the <%# PreviousPageType VirtualPath="~/WebForm1.aspx"%> to webform2.aspx page and check.
2.) OR if you keep the FriendlyURLs and hence the Routing system, make changes in your code to read the Form values using some other alternatives.
I'm new to ASP.NET and C#, I've primarily worked with Java. I want to dynamically add nodes to a tree view. I've followed a few tutorials but whenever I implement them they do not appear to work. I keep getting an error: "The name 'MyTreeView' does not exist in the current context".
Here's the C# code:
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace LocalTest
{
public partial class _Default : Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
MyTreeView.Nodes.Add(new TreeNode("Node1"));
MyTreeView.Nodes[0].ChildNodes.Add(new TreeNode("ChildNode"));
}
}
}
}
And the HTML/ASP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:TreeView ID="MyTreeView" Runat="server">
</asp:TreeView>
</div>
</form>
</body>
</html>
"MyTreeView" is the ID of the treeview contained in the Default.aspx file.
The few tutorials I have followed seem to access the treeview directly with its ID as seen above which makes very little sense to me. For instance, if I were to do this in Android I would have to use the findViewById and establish a link between the XML and the Object.
Does anyone have any suggestions? I've bumbled around this site for a bit and I'veonly found similar issues but I cannot get a clear answer.
Thank you.
Looking at the code above, you are using what's known as ASP.Net WebForms where there are "server side" controls (e.g. <asp:TreeView ID="MyTreeView" Runat="server">)
The "page" (html aspx) needs to somehow "wire itself" to the code (c# file). It will need a "server-side" directive like so:
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebFormsApplication.WebForm1" %>
<!DOCTYPE html>
//...the rest of the html goes here plus web controls, etc.
At which point, you can see stuff like Inherits="WebFormsApplication.WebForm1" that maps to the Class:
namespace WebFormsApplication
{
public partial class WebForm1 : System.Web.UI.Page
....
found in the WebForm1.aspx.cs file, also in the directive CodeBehind="WebForm1.aspx.cs"
So voila :)
establish a link between the XML and the Object.
Hth...
You do not have TreeView control in default.aspx. It is in .html file and default.aspx.cs can not see TreeView control.
It seems you are missing Page directive in your asp.net page
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1" %>
i am having lots of trouble getting started today... i keep getting
Parser Error
Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately.
Parser Error Message: Could not load type 'Webapp5.landing'.
Source Error:
Line 1: <%# Page Language="C#" AutoEventWireup="true" CodeBehind="landing.aspx.cs" Inherits="Webapp5.landing" %>
Line 2:
Line 3: <!DOCTYPE html>
here is my code behind....
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace Webapp5
{
public partial class landing : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
}
}
and here is my page...
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="landing.aspx.cs" Inherits="Webapp5.landing" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
</div>
</form>
</body>
</html>
i know i am missing something easy here.... but i just cant get seem to get this working?
any ideas on how to get this page to run?
I am trying to pass a value from a JScript function to an ASP.NET Control but I am not able to make it work. What am I doing wrong here:
aspx.cs
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication5._Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script type="text/javascript">
function saveMyData() {
var myData = "TestData";
var hiddenInput = document.getElementById('<%=HiddenField1.ClientID %>');
hiddenInput.Value = myData;
}
</script>
</head>
<body onload="javascript:saveMyData();">
<form id="form1" runat="server">
<div>
<asp:HiddenField ID="HiddenField1" runat="server" />
<br><input type="submit" value="Press Me!"><br> <--New Code
</div>
</form>
</body>
</html>
Code Behind:
using System;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
namespace WebApplication5
{
public partial class _Default : Page
{
protected HtmlInputHidden HiddenField;
protected void Page_Load(object sender, System.EventArgs e)
{
string value = HiddenField1.Value;
}
}
}
**UPDATE**
I added in a Submit button but I am still not able to assign the myData Value to the Hidden Control, any thoughts?
All you're missing is a postback. You will need the page to post back before it is able to read the newly inserted value into HiddenField1. The javascript is adding the value to HiddenField1 after Page_Load.
What are you trying to do? From what it looks like, you try to read out the value you set via Javascript (on the client side), but you never actually returned the data to the server.
You wont be able to read it without a PostBack, because the javascript does not get executed on the server side.
Add a button, make a Postback and see if you can read out the data then.
Developing is more of a hobby at the moment; so apologies if this is a basic question, although after a couple of hours searching the web I can't seem to find an answer. I am currenttly building a support tool for my team which runs a number of SQL queries & BCP processes and returns the results. Some of these actions take quite a while and I would like to update the web UI with status messages. Previously I have been using the Label1.Text = text;
However now I would like to update the Label1.text multiple times while my method is running. Try as I might though it only displays the last update in the method.
I have coded a small test to try get to the bottom of this: -
Web Page
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="Template._Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Label ID="progress" runat="server" Text=""></asp:Label><br />
<asp:Image ID="Image1" runat="server" ImageUrl="~/Image/loader.gif"
Visible="False" />
</div>
</form>
</body>
</html>
C# CodeBehind
using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Data.Odbc;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
namespace Template
{
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
uiUpdate("OUT", 1);
wait();
uiUpdate("In", 0);
}
protected void uiUpdate(string text, Int32 image)
{
if (image == 1)
{
Image1.Visible = true;
}
else
{
Image1.Visible = false;
}
progress.Text = text;
}
protected void wait()
{
DateTime wait;
wait = DateTime.Now + TimeSpan.FromSeconds(10);
while (wait > DateTime.Now)
{
}
}
Is there a way I can get the Label1 & Image to update as the Page_load is running?
Or am I looking at this the totally wrong way (no doubt!)
Thanks
HTML as a full page request is not in the least bit granular:
your browser sends a request (of all the form variables, cookies, etc etc) to the server
the server does a bit of processing and sends a response (typically html)
your browser processes the response and renders the display
All your updates are happening in the middle bullet, so no: there is no way to make the browser update: your code is executing on the server, with no dialog with the client
If you need this type of behaviour, you would have to look at AJAX tools - at each step doing "just enough" work to get to the next milestone and update the caption... with regular ASP.NET UpdatePanel may be of interest; for MVC or other (non-ASP.NET) setups, jQuery would be your friend. Unfortunately, this isn't a trivial topic.
If I understand your question correct you can't do this in regular asp.net, you need to use ajax, and make an ajax method in which you then update the text of the label on runtime. You can use the ajax MS scriptmanager to do this.
If it is not for high performance you can use an update panel otherwise you should just use the scriptmanager by yourself.