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fluid template: passing a javascript varible as the argument value?

For a f:link show action in my fluid list template i want to pass a javascript variable to the arguments, basically the uid (to pass that specific object to the showAction), but it doesn't work the way i intend to do it. Is there a workaround for this particular problem?
The naked template looks like this:
<f:for each="{termins}" as="termin">
<tr>
<td><f:link.action action="show" arguments="{termin : termin}"> {termin.mitarbeiter}</f:link.action></td>
<td><f:link.action action="show" arguments="{termin : termin}"> {termin.kunde}</f:link.action></td>
</tr>
</f:for>
</table>

You can't - and you also can't (read: never should) generate links to controller actions from JS since it needs to generate a security checksum. Modifying the URL you create will generate a security error. The checksum exists to prevent DDOS so it has good reason.
There are two options:
You can generate all links in advance
You can make a link-generating service that you call with XHR to generate the necessary links from JS.
Only the first one is appropriate to your use case. Especially so since you want to pass UID values which always refer to an object in the database - which means you can easily generate a list of links to all possible detail views, then read/pass that list of links from your JS to select the right one.

The JS is something working after the fluid template. The right order is, your fluid template is parsed into the HTML, and then the browser render the HTML/JS/CSS to you. So, you can not expect to use JS value in your fluid template.

There are 2 possibilities:
1) Instead of a link use a form and transmit it via POST. Set a form field dynamically with JavaScript. That way your variable isn't included in the (cHash-) checksum.
2) Create an AJAX action that accepts your variable as argument. Let it generate a valid link. Use POST to call it with your variable data. Show the link on your page with JavaScript.

Listen to Response on HTML Form embedded in GWT View?

I have a HTML like the following:
<div>
<form>
<input type="text" />
<button class="sendForm" value="Send form" />
</form>
</div>
<script>
// post the form with Jquery post
// register a callback that handles the response
</script>
I use this type of form a lot with a JavaScript/JQuery overlay that displays the form. That could be handled for example with plugins like FancyBox. I use Fancybox for Ajax content.
I also want to use this form embedded into a GWT view. Lets assume that the for cannot be created on client side because it has some server based markup language inside to set up some model data.
If I want to use this form in GWT I have to do the following. Tell GWT the form request url and use a RequestBuilder to query the html content of this form. Then I can insert it into a div generated by GWT. So far so good.
Problem:
When the user hits the send button the response is handled my the JQuery callback that is inside the script under the form.
Is there a way to access this callback from within GWT?
Is there a way to overwrite the JQuery send action? Since, the code is HTML and comes from the server I cannot place ui-binder UiFields inside to get access to these DOM elements.
I need to get the response if the submitted form accessible to GWT.
Is there a way how I can achieve this with JSNI?

Answers to each question:
1 Is there a way to access this callback from within GWT? actually you cannot modify the callback itself, what you can do from GWT is to call any jquery method, thus you can unbind any previous added handler, and set yours.
//NOTE: not wrapping code in $entry() to make a clearer code.
private static native unbindForm() /*-{
// remove all jQuery handlers added previously to my form
$wnd.$("my_form_selector").off();
// add a new handler for the submit event
$wnd.$("my_form_selector").on("submit", function(event) {
event.preventDefault();
$wnd.$(this).post(url, ...).done(function(data) {
// Use JSNI to call a GWT method
#.com.example.MyClass.handleFormResponse(*)(data);
// NOTE: that you can use a star instead of having to write parameter
// types, when you only have one method signature in your class.
});
}
}-*/
// handle the form response in GWT
public static void handleFormResponse(String data) {
// handle form response in GWT
}
Another thing you can do with GWT, is to wrap your form in a FormPanel and use specific widget methods to set a handler and read the response. But I think this is not what you are asking for.
2 Is there a way to overwrite the JQuery send action Yes, using JSNI to ask jQuery to unbind previously set events. See code in #1.
3 I need to get the response if the submitted form accessible to GWT. You have to include in the jquery.post callback some code to call GWT static methods (you can use-non static as well but this way is easier) this is also JSNI. See code in #1.
4 Is there a way how I can achieve this with JSNI? Of course, JSNI is the way to interact with handwritten javascript from GWT.
Aditional Notes:
GWT is designed to build RIA apps with very optimized js code. I know each one has their reasons for using external libraries, but adding 3party javascript to your app is against the main goals of gwt compiler remove death code and optimize output. If you like jquery like syntax and features for GWT I recomend to use gwtquery, which has been fully written in gwt, hence the compiler will include just the code you use.
Writing JSNI is a source of mistakes difficult to handle in the debugger. So I recommend to use gwt-exporter to populate java methods/classes or gwtquery to call external javascript. See these post I wrote some time ago: Pass value from GWT to Javascript via JSNI and Calling GWT Java function from JavaScript

Javascript => GWT and GWT => javascript values passing both can be done using JSNI . Please have a look here for more information about JSNI

MVC3 Using Javascript to postback similar to how $.post works -- but with an actual postback?

I have an ASP.NET MVC3 app that features a form with a nested-table input
(Ie on each row I can add a sub-table, with no limit on depth)
To handle this for my MVC app, I've created 2 javascript classes(using this term loosely with js:) that mirror my MVC3 model and post the data to an action method. Everything works great...Except that right now the only way that I know how to do this is with jquery $.ajax or $.post --- How can I do a postback in javascript?
I have the URL, and the custom JSON data, and want to do a page postback... Any suggestions? I can't use the normal form submit due to the nested table scenario described above.
Also, I just want to say, that MVC has made this so simple to render! :) For rendering a recursive view did everything without any script required, only on the saving did I need to screw around with json.
Update:I guess another solution would be -- can I change the contents of my form data on submit? My method takes a JSON object, is there any way I can stuff that in my request while my form submit is happening normally?

You can use the XML Http Request to do this. This is eventually what jQuery and other JS libraries use.
But why don't you just stick to jQuery AJAX or POST?

Maybe I'm misunderstanding your question, but it seems like what you want to do is post to the same page you are on, which means if you have the URL (and it sounds like you do), you just need to specific that in the $.ajax method? Maybe you can clarify what you mean a little bit for us.
Edit: Per comment suggested looking at http://jquery.malsup.com/form/

Well, I found that with the MVC3 binding, the table in my form could be normally bound if I named the fields such as Item[0].Children[1].Children[0].FieldA... etc, everything matched up fine without having to convert to javascript objects/json. I changed my code to fix this naming before a form submit, and it binds pretty well without having to do any json calls at all. Less elegant, but I guess it works.

asp.net MVC Partial Views how to initialise javascript

I have an edit form that uses an ajax form to submit to the controller. Depending on the data submitted I redirect the user to one of two pages (by returning a partial view). Both pages rely on javascript/jquery and neither use anything common between the pages.
What is the best way to initialise these javascripts on each page? I know there is the AjaxOption OnComplete but both pages are quite dynamic depending on the Model passed and I would rather keep the javascript for both pages seperate rather than having a common method.
Thanks

If you are using jQuery then in the partial pages you can write
$(document).ready(function() {
// put all your javascript initialisation here.
});
Update: Above will not work. So you can try this.
You can call a method on On_PartialLoad() on AjaxOption.OnComplete. Each of this partial can provide there own implementation of On_PartialLoad().
So In Partial1 you can have
function On_PartialLoad(){
//Partial_1 Implementation
}
So In Partial2 you can have
function On_PartialLoad(){
//Partial_2 Implementation
}

Server or CLIENT side Custom ASP.Net Controls?

I am an undergraduate student ,
and working on my Final Year project these days.
I have some queries related to Custom Controls as follows:
I am designing a text box field which will have three or more functions as follows :
Either it will allow numeric characters only
Or it will allow an email address to be taken as input
Or it will be a file Upload text box
I am using jQuery to validate this text box .for eg. for checking whether the user has entered numeric characters only or not!!
My Question is
What is the better approach to build such custom controls ? Either make it pure client side or pure Server side or both?
Also , I need to include AJAX functionality in file uploader.
If the client browser doesnot support JavaScripting for some reason then how we can avoid this constraint ?
Thank you very much for your time !
Kindly help me.

First of all you have to decide if you need both client-side and server-side functionality for your control. It will depend on your needs. If you are writing it as part of a large application, I would suggest going for both, because it's much easier to manage. If you decide that you do want both, ASP.NET includes exact functionality that you are looking for. It's called Extender controls. They will allow you to create a custom server-side control and extend that control to include some client-side functionality. You can get more information about Extenders here.
Graceful failing AJAX controls are rare, majority of the developers that create AJAX controls assume that all clients will have JavaScript turned on. However, they are not that hard to do. Actually they are very easy to do, if you are using ASP.NET AJAX Update Panel. Update Panel itself will automatically switch to full post-back if JavaScripts are disabled. If you are using custom implementation of AJAX, or jQuery (as you mentioned above), you have to follow a few simple rules. First of all, avoid binding events from inside scripts, use onclick, onmouseover, etc. This way, if a link has onclick event, and a valid href tag, if JavaScript are on, you will process onclick event handler, but if they are off, you will just follow href attribute value. For the uploader, you can put your uploader inside the FORM element, and add onsubmit event to it. If JS is on, you will process onsubmit, and do an AJAX call to save the file, if JS is off, you will do a full page post-back and save the file from the server-side.