We have a web control that we want to render into a div on the already loaded page. This needs to happen when the user clicks on a hyperlink in the menu.
The web control has some javascript files that are added to it dynamically in the C# code.
We also arent using aspx files, and want to load the web control onto a normal html page.
Please let me know what would be the best way to do this, or direct me to an article as I'm struggling to find anything useful on the web. any help is appreciated.
You can render your control dynamically in a string, send the string back and place it inside your div. Using ajax you call the code behind to render the control and return you the results.
// load the control
var oCConrol = Page.LoadControl("CustomControl.ascx");
// here you need to run some initialization of your control
// because the page_load is not loading now.
// a string writer to write on it
using(TextWriter stringWriter = new StringWriter())
{
// a html writer
using(HtmlTextWriter renderOnMe = new HtmlTextWriter(stringWriter))
{
// now render the control inside the htm writer
oCConrol.RenderControl(renderOnMe);
// here is your control rendered output.
strBuild = stringWriter.ToString();
}
}
Alternative you can get the same results by just make an extra empty aspx page with only your control inside and call it using Ajax. The result will be again the control
The javascript how ever is dificult and can not go with the control. You can not send text back and then make it run as javascript inside the control, this must be done separated.
I have done something similar by creating a separate, standalone .aspx page and Jquery ajax. Call to the .aspx page using Jquery ajax and return all the rendered HTML from that page via the ajax response.
As far as I know, there is not any way to render a web control outside the context of a .aspx page.
Related
I have a main web page ("Base Page") that makes an ajax call (using jQuery) to the server. The server-side page ("Ajax Page") is an ASP.NET web form (no MVC in use here). Because (in this case) I'm using a GridView to render data within the ajax response, I have to include the <form runat="server"> tag.
My complaint is this--when the Base Page receives the AJAX response, it inserts it into the DOM, but because the AJAX response is comprised of HTML markup that includes a <form> tag, this sometimes results in nested html forms, which is bad.
I realize that I can use jquery to only insert a fragment of the response into the Base Page DOM--or that I could use jquery to subsequently strip out the offending <form> tag. But these feel like klunky work-arounds. Is there really no way to prevent the ASP.NET page from serving out its response with a <form> tag? I realize that the form tag is the heart of the ASP.NET webform model, but it sure makes using AJAX in ASP.NET a complicated affair--very much swimming upstream. Surely Microsoft has realized that the postback / server-side model is a thing of the past?
I also realize that Microsoft has some server-side AJAX libraries that probably address this issue--but I'd still like to know if there's a solution native to ASP.NET webforms.
Any suggestions?
You can add your GridView to a Web User Control and then render it to a string like this:
public static string ExecuteToString(this Control control)
{
Page page = new Page();
page.Controls.Add(control);
StringBuilder sb = new StringBuilder();
using (StringWriter writer = new StringWriter(sb))
{
HttpContext.Current.Server.Execute(page, writer, false);
}
return sb.ToString();
}
This means you don't need to point your ajax request to a page. You can use a web service. Query a specific method and then dynamically load the User Control, render it to a string and return the HTML. Because you put your HTML and code in a User Control you don't need to worry about stripping out form tags and you can still use all the asp controls as you would on a page.
I have no idea about the performance costs of using this method but I've been using it for a while and it seems fine to me.
Working with WebForms & AJAX for many years I can understand your frustration.
Usually when working with loading WebForm pages using jQuery AJAX, I wrap an ajax class around my page, just nested inside the form:
<html>
<head></head>
<body>
<form runat="server">
<div class="ajax">
Content here..
</div>
</form>
</body>
</html>
Then when I load the page, I call just this ajax class:
$("element").load("http://domain.com/webpage.aspx .ajax");
This means the form element isn't rendered into my page, preventing nested form issues, but your GridView can still be rendered into HTML successfully.
I was dealing with the same kind of issue, I resolved it the following way:
Response.Write("whatever content")
Response.End()
This will send ONLY what you put in "Response.Write()"... You're still free to alter headers, etc.
If your ajax server page is an aspx page(ex : ajaxpage.aspx) , you can remove the HTML makup in the ajaxpage.aspx except the first line which mentions the Page directive. So it should be something like this.
<%# Page Language="C#" CodeBehind="ajaxpage.aspx.cs" Inherits="MyProject.ajaxpage" %>
And in the code behind, you can return the data using response.Write
protected void Page_Load(object sender, EventArgs e)
{
Response.Write("your markup to return here");
}
If it is to return some kind of (clean) HTML markup / some part of data, I am inclined to use a generic handler (ex : ajaxresponse.ashx )file instead of an aspx file and return data from that
public void ProcessRequest(HttpContext context)
{
context.Response.ContentType = "text/plain";
context.Response.Write("<h3>Here is the Markup for UserDetails</h3>");
}
You can not use ASP.NET server controls on an ashx file. And you can not have a page to have a server control (ex : GridView ) without a form tag. It should be placed inside a form tag. Note that your server controls like gridview is going to render an HTML table markup only.
Personally if i want to get some clean & controlled HTML markup which i want to show /inject into my current page using ajax, i will use an ashx handler and write my code to output my required markup. ASHX files has performance advantages compared to a aspx file as it wont go thru the normal ASPX page life cycle ( All those events !).
I have a master page which contains everything that inherits it within a form. A page inheriting from it needs to run some javascript to act on a text field on a page. However, I can't seem to reference that text field through the javascript, since the form begins on the master page.
The following line will come up bogus:
document.form1.txtFindUser.value = blah.responseText;
This is because form1 is defined on the master page, while txtFindUser is on the current page.
How can these situations be handled?
How about that :
document.getElementById('txtFindUser').value = blah.responseText;
But if txtFindUser is your server control's id, then you should use the code above like that :
document.getElementById('<%= txtFindUser.ClientID %>').value = blah.responseText;
Page elements don't always have the same name at runtime than they do in design time in .NET. View the source of your page when you ran it and see what txtFindUser is called after it was interpreted by IIS.
any server controls on the page will render with a different name since that page is derived from a master page. (I guess this removes complexities which can arise out of using same names for controls in your master page as well as in the derived page).
var ctrl = '<%= txtBox1.ClientID %>';
document.getElementById(ctrl).value='Hello world';
Refer to this post for more info
Is it possible without encapsulating these controls in aspx files? The Register tag makes me think that it is not.
You can't call ascx page directly, they can't serve any html without added to aspx or render then dynamically in response to any page/handler.
One possible way would be to have a generic aspx stub page that acts as a host to the ascx in the normal web forms way make a callback to the that page using JQuery's $.ajax() method with some arguments to denote what ascx control you want to load.
Then on your stub / host page, override the render method and render the control directly to the output stream using response.output.write. The callback handler on the client will catch the output and then it can be inserted into the DOM in the normal way or using using the version of $.load() that allows the specification of a DOM element.
hope this helps.
This is one way to load ASCX controls through jQuery, using an ASMX service that creates a Page instance to render the user control.
Since I've started using jQuery/Ajax more and more, I find I've been using server controls less and less.
Things that I used to put into controls are now just individual aspx pages which get loaded into panels.
If you have old ASCX files, it shouldn't be too hard to convert them to ASPX
No.
That said, you could place your ascx inside an UpdatePanel and set the panel's content visible/invisible using the standard Asp.Net postback mechanisms.
Or you could write a separate IHttpHandler which generates HTML code that your Javascript code adds to the page using DOM. This part of the page would however not be accessible in PostBack.
No, ASCX are user-controls, that exist on ASPX. You will need to make it a Page, or convert into Handler.
From time to time I run into situation in which I could solve a given problem by dynamicly creating piece of JavaScript, spesific to that instance of the page, that I could then insert in the final markup. Usualy this is because I want some behaviour to happen on the client side, rather than on the server side and creating a static JavaScript isn't an option.
For example, when trying to submit a files original path without submitting the file itself, when trying to do it for multiple dynamicly created components.
How would you recommend me to create a script tag and populate it with, for example, JavaScript?
Use your page's ClientScriptManager and it's RegisterClientScriptBlock() method.
string javascript = "javascript goes here";
string scriptname = "Name of this script"; // used to prevent adding the same script twice at two places in the page life cycle
if (!Page.ClientScript.IsClientScriptBlockRegistered(scriptname))
{
Page.ClientScript.RegisterClientScriptBlock(this.Page.GetType(), scriptname, javascript, true);
}
In an ASP.NET page I have a user control and I want to perform some action within it using javascript. When that action is complete I want to raise an event (again in javascript) to be picked up by the containing ASP.NET page (again in javascript).
The reason I want to do this is because I have more than one user control on the page and I need the action performed in one user control to instantiate an action in another user control without doing a postback.
Does anyone know how to do this?
Many thanks.
Hi and thanks for the response.
What I'm trying to do is create some form of encapsulation. So if the javascript code does something in one user control that user control shouldn't know of the impact else where. It would raise an event in javascript which can be picked up by asp.net page rendered javascript which can in turn call a javascript method in another user control if it needs to.
The idea here is also to eliminate any need for a postback.
Hope this expains it better.
I think the simple way to implement what you are describing, is to forget about JavaScript events, and just supply a "callback" function to the user-controls.
The way i would implement it, would be to expose a public property on the user control, which takes the name of this JavaScript "callback-function". The user-control is then responsible for calling this function after it has finished its client-side job.
So the page that uses the user-controls will have to implement this JavaScript "callback-function", and then supply the name in properties to the user controls.
Makes sense?
You can simply run the javascript you need from the rendered HTML of your user control.
Click Me
By the sounds of things you want to create some form of controller in JavaScript. When the page loads each of your controls register with the controller. Then an action in one of your controls runs a function on the controller, which does something with the controls registered with it.
Your JavaScript could be as simple as:
var oControls = new Array();
doSomething = function() {
for(var i=0;i<oControls.length;i++) {
var oControl = document.getElementById(oControls[i]);
oControl......
}
}
So you need to register your control by using ScriptManager in your user controls render method.
ScriptManager.RegisterStartupScript(Me, Me.GetType(), "Startup", String.Format("oControls.push('{0}');", ClientID), True);