I´m looking for a possibillity to prevent all functions from being executet while an ajax post is in progress. For example: I have a modal box where you can switch between two forms with a simple tab-navigation. When a user submits one of the forms, the data will be sent via ajax. So how can I avoid that the user can switch between the forms till the post is finished.
Is there a simple way to do that?
something like event.stopImmediatePropagation() during the ajax post.
Simple way to do that is just display an overlay. An element that takes up the whole screen and has no event handlers. The most popular option seems to be semi transparent div with a loading indicator to give user an idea about what's happening and that nothing will work on the website until request finishes.
Example: http://jsfiddle.net/NezTc/11/
i am not sure if other methods exist but i would bind a listener for all submits and check there if a flag for ongoingAjax request is set. This flag would be set by my ajax calls.
something like
$(function(){
var onGoingAjaxRequest = false;
$('form').submit(function() {
if(!onGoingAjaxRequest) {
return true;
}
return false;
});
});
I'm not sure you can "cut off" all functions until a given point in time, but I know you can always:
Header all functions with if(isPosting) return; and add
var isPosting = true
$.ajax({ [...], complete:function(r){ // this is the ajax function
isPosting=false;
}});
Or, overlay the whole thing and add a big preloader and a Please wait... message.
Related
I do have an accordion kind of UI, where for a user there are several nodes to click and expand. On the click of those Nodes,I need to make an Ajax call to one my server side programs.The idea here is make the call, and listen for success or failure and either case , return back with the Model Object that my view needs to pick and subsequently pass to the Underscore template to display the values appropriately.
Haven't written a BackBone Ajax call before, and so was interested knowing from experts there, for a given need what should be my best strategy.
Your answers are much appreciated.
Sharad
You have 2 options which are basically equivalent and depend on taste. Using callbacks:
myModel.fetch({
success: function(model, response, options){
// create and display new view
},
error: function(model, response, options){
// display error
}
});
Or the equivalent using deferreds:
myModel.fetch().done(function(){
// create and display new view
}).fail(function(response){
// display error
});
So I have an ajax call to bring down several dozen chunks of data all several megabytes in size, afterward storing the data locally via the html5 filesystem api.
I wanted to prevent the user from navigating away from the page before the ajax calls were done. I decided to explore the onbeforeunload event, to have it notify that the user should stay on the page until the ajax calls are complete. I set the following before the AJAX call and at the end/success of the AJAX call I reset the window.onbeforeunload.
window.onbeforeunload = function(){
return "Information is still downloading, navigating away from or closing "+
"this page will stop the download of data";
}
When I attempted to close the page or navigate away from the page, the pop-up message comes up as expected informing the user to stay. However, once I confirm that I want to stay on the page, the ajax calls do not resume where they left off. Is there a way to prevent the ajax calls from pausing/stopping or to continue on/restart with their executions?
I'm open to any ideas to implement desired functionality described in the title of this post.
Pretty sure you can create a global in the .js file like...
var request;
Then assign your ajax call to this variable.
request = $.ajax{
//Ajax
//Stuff
//Goes
//Here
}
Now inside your window.unbeforeunload function, add this conditional statement.
window.onbeforeunload = function(){
if(!request){
return "Request not initiated";
}else{
//Request is in progress...
//You can use request.abort() if you need
}
}
EDIT: To elaborate on on some of the methods you can use on the request object, check out this page. (for example, .done or .always may suit your circumstances)
I'm confused as to how to accomplish this. I have a page which, has a popup filter, which has some input elements and an "Apply" button (not a submit). When the button is clicked, two jquery .get() calls are made, which load a graph, a DataTables grid, photos, and miscellaneous info into four separate tabs. Inside the graph, if one clicks on a particular element, the user is taken to another page where the data is drilled down to a finer level. All this works well.
The problem is if the user decides to go back to the original page, but with the ajax generated graph/grid/photos etc. Originally I thought that I would store a session variable with the filter variables used to form the original query, and on returning to the page, if the session var was found, the original ajax call would be made again, re-populating the tabs.
The problem that I find with this method is that Coldfusion doesn't recognize that the session variable has been set when returning to the page using the browser's back button. If I dump out the session var at both the original and the second page, I can see the newly set var at the second page, and I can see it if I go to the original page through the navigation menu, but NOT if I use the back button.
SO.... from reading posts on here about ajax browser history plugins, it seems that there are various jquery plugins which help with this, including BBQ. The problem that I see with this approach is that it requires the use of anchor elements to trigger it, and then modifies the query string using the anchors' href attributes. I suppose that I could modify the page to include a hidden anchor.
My question, at long last is: is an ajax history plugin like BBQ the best way to accomplish this, or is there a way to make Coldfusion see the newly created session var when returning to the page via the back button? Or, should I consider re-architecting the page so that the ajax calls are replaced by a form submission back to the page instead?
Thanks in advance, as always.
EDIT: some code to help clarify things:
Here's the button that makes the original ajax calls:
<button id="applyFilter">APPLY</button>
and part of the js called on #applyFilter, wrapped in $(document).ready():
$('#applyFilter').click(function(){
// fill in the Photos tab
$.get('tracking/listPhotos.cfm',
{
id: id,
randParam: Math.random()
},
function(response){
$('#tabs-photos').html(response);
}
);
});
Finally, when the user calls the drill-down on the ajax generated graph, it uses the MaintAction form which has been populated with the needed variables:
function DrillDown() {
//get the necessary variables and populate the form inputs
document.MaintAction.action = "index.cfm?file=somepage.cfm&Config=someConfig";
document.MaintAction.submit();
}
and that takes us to the new page, from which we'd like to return to the first page but with the ajax-loaded photos.
The best bet is to use the BBQ method. For this, you don't have to actually include the anchor tags in your page; in fact, doing so would cause problems. This page: http://ajaxpatterns.org/Unique_URLs explains how the underlying process works. I'm sure a jQuery plugin would make the actual implementation much easier.
Regarding your other question, about how this could be done with session variables - I've actually done something similar to that, prior to learning about the BBQ method. This was specifically to save the state of a jqGrid component, but it could be easily changed to support any particular Ajax state. Basically, what I did was keep a session variable around for each instance of each component that stored the last parameters passed to the server via AJAX requests. Then, on the client side, the first thing I did was run a synchronous XHR request back to the server to fetch the state from that session variable. Using the callback method for that synchronous request, I then set up the components on my page using those saved parameters. This worked for me, but if I had to do it again I would definitely go with the BBQ method because it is much simpler to deal with and also allows more than one level of history.
Some example code based on your update:
$('#applyFilter').click(function(){
var id = $("#filterid").val(); // assumes the below id value is stored in some input on the page with the id "filterid"
// fill in the Photos tab
$.get('tracking/listPhotos.cfm',
{
id: id // I'm assuming this is what you need to remember when the page is returned to via a back-button...
//randParam: Math.random() - I assume this is to prevent caching? See below
},
function(response){
$('#tabs-photos').html(response);
}
);
});
/* fixes stupid caching behavior, primarily in IE */
$.ajaxSetup({ cache: false });
$.ajax({
async: false,
url: 'tracking/listPhotosSessionKeeper.cfm',
success: function (data, textStatus, XMLHttpRequest)
{
if (data.length)
{
$("#filterid").val(data);
$('#applyFilter').trigger('click');
}
}
});
This is what you need on the client-side to fetch the state of the photo list. On the server side, you'll need to add this modification to tracking/listPhotos.cfm:
<cfset session.lastUsedPhotoFilterID = URL.id>
And add this new one-line file, tracking/listPhotosSessionKeeper.cfm:
<cfif IsDefined("session.lastUsedPhotoFilterID")><cfoutput>#session.lastUsedPhotoFilterID#</cfoutput></cfif>
Together these changes will keep track of the last ID used by the user, and will load it up each time the page is rendered (whether via a back button, or simply by the user revisiting the page).
I've been using this link as a reference for developing my WebGrid (http://msdn.microsoft.com/en-us/magazine/hh288075.aspx).
Currently what is happening is that my WebGrid is loaded, and I'm able to asynchronously page and sort just fine...no problems. What is an irritation is that once I click to page or sort, the user isn't aware that anything is happening.
So what I'm looking for is a way to call a javascript function (or anything really) before the controller's action method is called, so that I have something appear to let the user know work is being done to return their next page, sort, and so forth.
I'm not sure if I'm just missing something, but any help would be appreciated.
You could use the .ajaxSend() and .ajaxComplete() methods to show and hide some spinner during the AJAX requests:
$(function() {
$('#grid').ajaxSend(function () {
// this will be called before the AJAX request is sent
// here you can show some spinner
$('body').append('<div id="spinner">Loading ...</div>');
}).ajaxComplete(function () {
// this will be called after the AJAX request completes and
// could be used to hide the spinner
$('#spinner').remove();
});
});
I have an app that has several different types of form elements which all post data to the server with jQuery AJAX.
What I want to do is:
Show a loader during AJAX transmission
Prevent the user from submitting twice+ (clicking a lot)
This is easy to do on a one off basis for every type of form on the site (comments, file upload, etc). But I'm curious to learn if that is a more global way to handle this?
Something that's smart enough to say:
If a form is submitting to the server and waiting for a response, ignore all submits
Show a DISABLED class on the submitted / clicked item
Show a loading class on the class="spinner" which is closest to the submit item clicked
What do you think? Good idea? Done before?
Take a look at the jQuery Global Ajax Event Handlers.
In a nutshell, you can set events which occur on each and every AJAX request, hence the name Global Event Handlers. There are a few different events, I'll use ajaxStart() and ajaxComplete() in my code sample below.
The idea is that we show the loading, disable the form & button on the ajaxStart() event, then reenable the form and hide the loading element inside the ajaxComplete() event.
var $form = $("form");
$form.ajaxStart(function() {
// show loading
$("#loading", this).show();
// Add class of disabled to form element
$(this).addClass("disabled");
// Disable button
$("input[type=submit]", this).attr("disabled", true);
});
And the AJAX complete event
$form.ajaxComplete(function() {
// hide loading
$("#loading", this).hide();
// Remove disabled class
$(this).removeClass("disabled");
// Re-enable button
$("input[type=submit]", this).removeAttr("disabled");
});
You might need to attach to the ajaxError event as well in case an AJAX call fails since you might need to clean up some of the elements. Test it out and see what happens on a failed AJAX request.
P.S. If you're calling $.ajax or similar ($.getJSON), you can still set these events via $.ajaxStart and $.ajaxComplete since the AJAX isn't attached to any element. You'll need to rearrange the code a little though since you won't have access to $(this).
I believe you have to do 2 for sure and 3 to improve usability of your app. It is better to keep backend dumb but if you have a security issue you should handle that too.