I am deep in the bowels of my code base, and I need to render the contents of a partial url to a string.
Currently I am turning the relative url into a full url, then making a full web request for the content and converting it to a string. This is considered sub-optimal for various reasons .
My current thought is to wire up the HtmlHelper class and invoke RenderPartial, but I'm having trouble wiring up a new HtmlHelper object.
Any thoughts on other ways of accomplishing this?
I would use the RazorEngine for that, so you don't have to do web-requests. But you cannot use HtmlHelpers because they rely on HttpRequest which you don't have there.
I noticed in some code that [WebMethod] attribute is used in the code-behind file of an aspx page.
But as I remember it, this attribute is used to expose Web Service and it is often seen in asmx file.
So what's the difference between these 2 usages?
Thanks.
If that method is also static, you can call that method via javascript/ajax, without a full page postback.
Note that your ScriptManager needs to have the EnablePageMethods property set to true.
Webmethods in code behind are used for AJAX calls. If you are using jquery or similar and you need to implement an ajax functionality on your page then you will have to define you method with WebMethod attribute and have to make it public static. Then only it will work.
WebMethod's concept I feel has been taken from web services. Since asp.net didn't have any defined way of handling ajax requests to method of page behind, they have extended this feature to be used for code behind methods.
Keep a watch that being public static methods you may not be able to use your page class' internal properties here. so, you will need to deal with that.
I have a web site with a growing number of AJAX calls.
I have AJAX code that looks like this:
function setupNameAutocomplete(id) {
$(id).autocomplete({
source: function(request, response) {
$.ajax({
url: "selectName.aspx/getNameAutocomplete",
....
Originally, the above javascript code was used on a web page where a user typed in the name of a person to search for; I decided I wanted to have autocomplete on the name.
However, as I continued to develop the web site, I decided that I wanted to be able to use the same "name" autocomplete on many pages. Logically, it made sense to put my javascript code in an external .js file instead of repeating it on every page.
It also makes sense that I would want to put the .net code that handles the AJAX in its own file as well. The .net autocomplete code looks like this:
[WebMethod]
public static IEnumerable<string> getNameAutocomplete(string text)
{
IEnumerable<string> values = lookupNamesThatStartWith(text);
return values;
}
Naturally, it seemed like this codes belongs in an external .asmx or perhaps a .ashx file, but I can't get my javascript code working unless I call the above code from selectName.aspx.
How can I get my AJAX .net code in a separate code file?
If I understand your problem correctly, a viable solution would be to have a base class that your services inherit from that would implement the generic WebMethod.
That, or you could get it "pretty clean" by having the logic of the autocomplete lookup abstracted into a class and just call it from your WebMethods each time, as needed.
I'm working on customizing BlogEngine.Net to be able to return some HTML from an AJAX call. Basically I'd like to render a UserControl server-side and then return the resulting HTML to a client-side call.
I've done this many times in other applications using static PageMethods marked with the [WebMethod] attribute. But any time I try this with BlogEngine.Net, I get the full HTML of the page returned. It doesn't even look like the WebMethod is getting touched.
I've also tried to implement this as an HttpHandler, but I have the same result. As soon as I include a page (vanilla Page class) and use it to render the control, I get the full HTML of the page I am calling from instead of the generated code, leading me to assuming something is hijacking my code to render a Page.
Any ideas or alternate solutions to be able to render a user control server-side and return the HTML using the BlogEngine.Net framework?
If you look at the code of CommentView.ascx, they do the same thing using ICallbackEventHandler. That basically renders the comment preview and also the comment itself.
However, it should be possible to do it like you said too, with [WebMethod]. I have actually customized my own setup to change CommentView to use a [WebMethod] and it works fine.
For an example of their own [WebMethod] implementation, have a look at AjaxHelper under admin folder, it's a dummy page whose purpose is to serve these web methods.
The above are for BlogEngine.NET 2.6.
I'm about to start a fairly Ajax heavy feature in my company's application. What I need to do is make an Ajax callback every few minutes a user has been on the page.
I don't need to do any DOM updates before, after, or during the callbacks.
I don't need any information from the page, just from a site cookie which should always be sent with requests anyway, and an ID value.
What I'm curious to find out, is if there is any clean and simple way to make a JavaScript Ajax callback to an ASP.NET page without posting back the rest of the information on the page. I'd like to not have to do this if it is possible.
I really just want to be able to call a single method on the page, nothing else.
Also, I'm restricted to ASP.NET 2.0 so I can't use any of the new 3.5 framework ASP AJAX features, although I can use the ASP AJAX extensions for the 2.0 framework.
UPDATE
I've decided to accept DanP's answer as it seems to be exactly what I'm looking for. Our site already uses jQuery for some things so I'll probably use jQuery for making requests since in my experience it seems to perform much better than ASP's AJAX framework does.
What do you think would be the best method of transferring data to the IHttpHandler? Should I add variables to the query string or POST the data I need to send?
The only thing I think I have to send is a single ID, but I can't decide what the best method is to send the ID and have the IHttpHandler handle it. I'd like to come up with a solution that would prevent a person with basic computer skills from accidentally or intentionally accessing the page directly or repeating requests. Is this possible?
If you don't want to create a blank page, you could call a IHttpHandler (ashx) file:
public class RSSHandler : IHttpHandler
{
public void ProcessRequest (HttpContext context)
{
context.Response.ContentType = "text/xml";
string sXml = BuildXMLString(); //not showing this function,
//but it creates the XML string
context.Response.Write( sXml );
}
public bool IsReusable
{
get { return true; }
}
}
You should use ASP.Net Callbacks which were introduced in Asp.Net 2.0. Here is an article that should get you set to go:
Implementing Client Callbacks Programmatically Without Postbacks in ASP.NET Web Pages
Edit: Also look at this:
ICallback & JSON Based JavaScript Serialization
What do you think would be the best method of transferring data to the IHttpHandler? Should I added variables to the query string or POST the data I need to send? The only thing I think I have to send is a single ID, but I can't decide what the best method is to send the ID and have the IHttpHandler handle it. I'd like to come up with a solution that would prevent a person with basic computer skills from accidentally or intentionally accessing the page directly
Considering the callback is buried in the client code, it would take someone with equal determination to get either the querystring or the POST request. IE, if they have firebug, your equally screwed.
So, in that case, do whatever is easiest to you (Hint: I'd just use the querystring).
To handle repeating requests/direct access, I'd generate a key that is sent with each request. Perhaps a hash of the current time (Fuzzy, I'd go down to minutes, but not seconds due to network latency) + the client IP.
Then in the HTTPHandler, perform the same hash, and only run if they match.
You are not just restricted to ASP.NET AJAX but can use any 3rd party library like jQuery, YUI etc to do the same thing. You can then just make a request to a blank page on your site which should return the headers that contain the cookies.
My vote is with the HTTPHandler suggestion as well. I utilize this often. Because it does not invoke an instance of the page class, it is very lightweight.
All of the ASP.NET AJAX framework tricks actually instantiate and create the entire page again on the backend per call, so they are huge resource hogs.
Hence, my typical style of XmlHttpRequest back to a HttpHandler.
Since you are using only ASP.NET 2.0 I would recommend AjaxPro will which create the .ashx file. All you have to do is to pull the AjaxPro.dll into your web site. I developed an entire application with AjaxPro and found it worked very well. It uses serialization to pass objects back and forth.
This is just a sample on how to simply use it.
namespace MyDemo
{
public class Default
{
protected void Page_Load(object sender, EventArgs e)
{
AjaxPro.Utility.RegisterTypeForAjax(typeof(Default));
}
[AjaxPro.AjaxMethod]
public DateTime GetServerTime()
{
return DateTime.Now;
}
}
}
To call it via JavaScript it is as simple as
function getServerTime()
{
MyDemo._Default.GetServerTime(getServerTime_callback); // asynchronous call
}
// This method will be called after the method has been executed
// and the result has been sent to the client.
function getServerTime_callback(res)
{
alert(res.value);
}
EDIT
You also have to add
To the config. AjaxPro also works well side by side with APS.NET Ajax and you can pass C# objects from Client to Sever if the class is marked as [Serializable]
Just to offer a different perspective, you could also use a PageMethod on your main page. Dave Ward has a nice post that illustrates this. Essentially you use jQuery ajax post to call the method, as illustrated in Dave's post:
$.ajax({
type: "POST",
url: "Default.aspx/GetFeedburnerItems",
// Pass the "Count" parameter, via JSON object.
data: "{'Count':'7'}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(msg) {
BuildTable(msg.d);
}
});
No need for Asp.Net Ajax extensions at all.
You should use a web service (.asmx). With Microsoft's ASP.NET AJAX you can even auto-generate the stubs.
You can also use WebMethods which are built into the asp.net ajax library. You simply create a static method on the page's codebehind and call that from your Ajax.
There's a pretty basic example of how to do it here