I am using the sortable widget to re-order a list of items. After an item is dragged to a new location, I kick off an AJAX form post to the server to save the new order. How can I undo the sort (e.g. return the drag item to its original position in the list) if I receive an error message from the server?
Basically, I only want the re-order to "stick" if the server confirms that the changes were saved.
Try the following:
$(this).sortable('cancel');
I just encountered this same issue, and for the sake of a complete answer, I wanted to share my solution to this problem:
$('.list').sortable({
items:'.list:not(.loading)',
start: function(event,ui) {
var element = $(ui.item[0]);
element.data('lastParent', element.parent());
},
update: function(event,ui) {
var element = $(ui.item[0]);
if (element.hasClass('loading')) return;
element.addClass('loading');
$.ajax({
url:'/ajax',
context:element,
complete:function(xhr,status) {
$(this).removeClass('loading');
if (xhr.status != 200) {
$($(this).data('lastParent')).append(this);
}
},
});
}
});
You'll need to modify it to suit your codebase, but this is a completely multithread safe solution that works very well for me.
I'm pretty sure that sortable doesn't have any undo-last-drop function -- but it's a great idea!
In the mean time, though, I think your best bet is to write some sort of start that stores the ordering, and then on failure call a revert function. I.e. something like this:
$("list-container").sortable({
start: function () {
/* stash current order of sorted elements in an array */
},
update: function () {
/* ajax call; on failure, re-order based on the stashed order */
}
});
Would love to know if others have a better answer, though.
Related
I'm having trouble with a knockout model that is not binding on a subscribed update. I have a C# MVC page that delivers a model to the template which is parsed to Json and delivered raw as part of a ViewModel assignment for ko.applyBindings. I have a subscription to an observable that calls a method to perform an update of the viewModel's data. Irrelevant stuff pulled out and renamed for example usage:
var myViewModel = function (data) {
var self = this;
self.CurrentPage = ko.observable();
self.SomeComplexArray= ko.observableArray([]);
self.Pager().CurrentPage.subscribe(function (newPage) {
self.UpdateMyViewModel(newPage);
});
self.UpdateMyViewModel= function (newPage) {
var postData = { PageNumber: newPage };
$.post('/Article/GetMyModelSearchByPage', postData, function (data) {
ko.mapping.fromJS(data, {}, self);;
});
};
When I perform logging, I can see all of the data, and it all looks correct. The same method is used to produce both the initial model and the updated model. I've used this technique on other pages and it worked flawlessly each time. In this case however, I'm looking for it to bind/update SomeComplexArray, and that's just not happening. If I attempt to do it manually, I don't get a proper bind on the array I get blank. I'm wondering if there is something obvious that I'm doing wrong that I'm just flat out missing.
Edit: I don't know that ko.mapping can be pointed to as the culprit. Standard model changes are also not affecting the interface. Here is something that is not working in a bound sense. I have a p element with visible bound to the length of the array and a div element with a click bound to a function that pops items off of SomeComplexArray. I can see in the console log that it is performing its function (and subsequent clicks result in 'undefined' not having that function). However, the p element never displays. The initial array has only 2 items so a single click empties it:
<p data-bind="visible: SomeComplexArray().length === 0">nothing found</p>
<div data-bind="click: function() { UpdateArray(); }">try it manually</div>
-- in js model
self.UpdateArray = function () {
console.log(self.SomeComplexArray());
console.log(self.SomeComplexArray().pop());
console.log(self.SomeComplexArray());
console.log(self.SomeComplexArray().pop());
console.log(self.SomeComplexArray());
});
Edit 2: from the comment #Matt Burland, I've modified how the pop is called and the manual method now works to modify the elements dynamically. However, the ko.mapping is still not functioning as I would expect. In a test, I did a console.log of a specific row before calling ko.mapping and after. No change was made to the observableArray.
I created a test of your knockout situation in JSFiddle.
You have to call your array function without paranthesis. I tested this part:
self.UpdateArray = function () {
self.SomeComplexArray.pop();
};
It seems to be working on JSFiddle side.
I'm not really sure why, but it would seem that ko.mapping is having difficulty remapping the viewmodel at all. Since none of the fields are being mapped into self my assumption is that there is an exception occurring somewhere that ko.mapping is simply swallowing or it is not being reported for some other reason. Given that I could manually manipulate the array with a helpful tip from #MattBurland, I decided to backtrack a bit and update only the elements that needed to change directly on the data load. I ended up creating an Init function for my viewModel and using ko.mapping to populate the items directly there:
self.Init = function (jsonData) {
self.CurrentPage(0);
self.Items(ko.mapping.fromJS(jsonData.Items)());
self.TotalItems(jsonData.TotalItems);
// More stuff below here not relevant to question
}
The primary difference here is that the ko.mapping.fromJS result needed to be called as a function before the observableArray would recognize it as such. Given that this worked and that my controller would be providing an identical object back during the AJAX request, it was almost copy/past:
self.UpdateMyViewModel= function (newPage) {
var postData = { PageNumber: newPage };
$.post('/Article/GetMyModelSearchByPage', postData, function (data) {
self.Items(ko.mapping.fromJS(JSON.parse(data).Items)());
});
};
This is probably not ideal for most situations, but since there is not a large manipulation of the viewModel occurring during the update this provides a working solution. I would still like to know why ko.mapping would not remap the viewModel at the top level, but in retrospect it probably would have been a disaster anyway since there was "modified" data in the viewModel that the server would have had to replace. This solution is quick and simple enough.
I just migrated to backbone and have a strange behaviour.
I attach draggable to an element which is created by a script, thus not directly available in DOM.
EDIT:
The element that is created is .nav, $("#viewer") as container is already in the DOM.
In plain jQuery i used .on and mousemove event for this and it worked.
With backbone I use the same in the initialize method:
initialize: function(options) {
this.viewer = $("#viewer");
this.viewer.on("mousemove", '.nav', function() {
$(this).draggable();
});
This seems to work, but only one time.
After dragging the element one time, I can't drag it anymore.
Are there conflicts with the events? Am I missing something?
You have to refer to $('#viewer') after you've called render(). initialize is called before render, and so the DOM element doesn't exist.
Also, use this.$('#viewer'), and it will grab the element (after render) even if it hasn't been appended to your page's DOM.
myView = new ExampleView({ model: myModel });
$(body).append(myView.render().el);
myView.onRender();
// -------------
// Now on your view:
onRender: function() {
this.viewer = this.$('#viewer');
this.viewer.on("mousemove", '.nav', function() {
$(this).draggable();
});
},
UPDATE
You can also, to make such things simpler, customize Backbone to automatically call the onRender() function after rendering, by triggering an event or something.
Marionette.js (a Backbone.js extension) has this built in and I use it all the time.
The solution finally was pretty easy:
make sure you dont use outdated versions of backbone.js and underscore!!
After i updated the versions to latest I made it work with:
render: function() {
this.viewer.on("mouseover", '.nav', function() {
if (!$(this).data("init")) {
$(this).data("init", true);
$(this).draggable();
}
});
Probably still not very elegant but i couldnt made the suggested onRender method from dc2 work.
In the ASP MVC page I'm currently working on, the values of three input fields determine the value of a fourth. Zip code, state code, and something else called a Chanel Code will determine what the value of the fourth field, called the Territory Code, will be.
I just started learning jQuery a couple weeks ago, so I would first think you could put a .change event that checks for values in the other two fields and, if they exists, call a separate method that compares the three and determines the Territory code. However, I'm wondering if there is a more elegant way to approach this since it seems like writing a lot of the same code in different places.
You can bind a callback to multiple elements by specifying multiple selectors:
$(".field1, .field2, .field3").click(function() {
return field1 +
field2 +
field3;
});
If you need to perform specific actions depending on which element was clicked, another option would be to create a function which performs the actual computation and then invoke that from each callback.
var calculate = function() {
return field1 +
field2 +
field3;
};
And then invoke this function when on each click:
$(".field1").click(function() {
// Perform field1-specific logic
calculate();
});
$(".field2").click(function() {
// Perform field2-specific logic
calculate();
});
// etc..
This means that you do not repeat yourself.
This works for me
jQuery(document).on('scroll', ['body', window, 'html', document],
function(){
console.log('multiple')
}
);
Adding another possibility, just in cased this may help someone. This version should work on dynamically created fields.
$("#form").on('change', '#Field1, #Field2, #Field3', function (e) {
e.preventDefault();
console.log('something changed');
});
I'm trying to dynamically populate a select tag at load time (latest jQM version) using a custom template filling function.
If the fn is called in the "pagebeforechange" event, the select tag is properly initialized. Since this event is called on every page transition, I thought of moving the fn to the 'pageinit' event. This does not work, presumably because the DOM is not yet fully available. How can I coerce jQM to inject content in a page only once? Currently, I am using a kludge. There surely must be a smarter way. Thanks for any suggestions.
$(document).bind('pageinit', function () {
InitSelTagTest("#selActTag", "tplTag"); // Does not work.
});
$(document).bind("pagebeforechange", function (e, data) {
if ($("#selActTag").children().size() === 0) {
InitSelTagTest("#selActTag", "tplTag"); // Kludge, but it works
}
});
function InitSelTagTest(el,tpl) { // Append all tags to element el
var lstAllTags = JSON.parse($("#hidTag").val()); // Create tag array
// Retrieve html content from template.
var cbeg = "//<![" + "CDATA[", cend = "//]" + "]>";
var rslt = tmpl(tpl, { ddd: lstAllTags }).replace(cbeg, ").replace(cend,");
$(el).html(rslt).trigger("create"); // Add to DOM.
}
EDIT
In response to Shenaniganz' comment, it seems that the "pagebeforecreate" event could do the trick ie.
$("#pgAct").live("pagebeforecreate", function () {
// Populate tag select. Works. Traversed only once.
InitSelTag("#selActTag", "tplTag");
});
I'm not sure I fully understand your question but I'll throw a few things out there and you let me know if I can extend further.
To make something trigger only once on page load you can try to implement a regular JQuery $(document).ready(function(){}) aka $(function(){}) for the exact reason why JQuery Mobile users are told not to use it. It triggers only once on DOM load. Further pages don't trigger it because they're being switched via Ajax.
Other than that, on regular dynamic content loading you take a look at the following example I put together for someone else earlier:
http://jsbin.com/ozejif/1/edit
I have a sortable list of videos and a draggable set of videos. Basically I want to make sure that the videos dragged in are not in the first 5 minutes of video. As the video lengths vary I want to test this on the drop - add up the time up to then and if not 5mins revert and show an error.
I have tried hooking into all of the callbacks for draggable and sortable (including the undocumented revert callback) to do my test but whatever I try, the dom always gets changed (and sortable calls its update callback)...
Does anyone have any suggestions?
You can revert the drag operation by calling the cancel method of the draggable widget (that method is undocumented, but its name does not start with an underscore, which arguably makes it "safer" to use reliably). It only works during the start event, though, as other events occur too late to trigger the revert animation.
However, the sortable widget will still register a drop even if the drag operation is canceled, so you also have to remove the newly-added item (during the stop event, as the start event occurs too early):
$("#yourSortable").sortable({
start: function(event, ui) {
if (!canDropThatVideo(ui.item)) {
ui.sender.draggable("cancel");
}
},
stop: function(event, ui) {
if (!canDropThatVideo(ui.item)) {
ui.item.remove();
// Show an error...
}
}
});
You can see the results in this fiddle (the fourth item will always revert).
Update: As John Kurlak rightfully points out in the comments, the item does not revert because of the call to draggable("cancel"), but because ui.sender is null in our case. Throwing anything results in the same behaviour.
Alas, all the other combinations I tried result in the item being reverted without the animation taking place, so maybe our best bet is to avoid accessing ui.sender and instead write something like:
start: function(event, ui) {
if (!canDropThatVideo(ui.item)) {
throw "cancel";
}
}
The uncaught exception will still appear in the console, though.
I found a different way. If you dont mind not having the animation of it floating back to it's original place you can always use this
.droppable({
drop: function (event, ui) {
var canDrop = false;
//if you need more calculations for
//validation, like me, put them here
if (/*your validation here*/)
canDrop = true;
if (!canDrop) {
ui.draggable.remove();
}
else{
//you can put whatever else you need here
//in case you needed the drop anyway
}
}
}).sortable({
//your choice of sortable options
});
i used this because i needed the drop event either way.