[
https://issues.apache.org/jira/browse/WICKET-6532?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Sven Meier closed WICKET-6532.
------------------------------
Resolution: Not A Problem
Assignee: Sven Meier
You're sending each file with a separate Ajax request. Since the queuing is
done by Wicket actually, you can easily use preconditions as follows:
{code:java}
diff --git
a/src/main/java/org/apache/wicket/ajax/res/wicket-drag-and-drop-file-upload.js
b/src/main/java/org/apache/wicket/ajax/res/wicket-drag-and-drop-file-upload.js
index d096224..30c72b5 100644
---
a/src/main/java/org/apache/wicket/ajax/res/wicket-drag-and-drop-file-upload.js
+++
b/src/main/java/org/apache/wicket/ajax/res/wicket-drag-and-drop-file-upload.js
@@ -143,13 +143,15 @@
'value': f
}
}),
+ pre: [
+ function (attributes) {
+ return !uploadContext.cancelled;
+ }
+ ],
bsh: [
function (attributes, jqXHR, settings) {
settings.xhr = function () {
try {
- if (uploadContext.cancelled) {
- return null;
- }
if (uploadContext.item) {
/* Add progress indicator */
xhr.upload.addEventListener("progress", function (e) {code}
This works fine here, and I can cancel each file ad libitum.
> It should be possible to cancel AjaxRequest like in jQuery beforeSend
> ---------------------------------------------------------------------
>
> Key: WICKET-6532
> URL: https://issues.apache.org/jira/browse/WICKET-6532
> Project: Wicket
> Issue Type: Improvement
> Components: wicket
> Affects Versions: 8.0.0-M8
> Reporter: Andrew Kondratev
> Assignee: Sven Meier
> Priority: Minor
>
> Was already discussed in
> [https://github.com/apache/wicket/pull/256#issuecomment-359985835]
> A little demo [https://github.com/andruhon/WicketDragAndDropFileAjaxUpload]
> (open the EventDemo page, enable slow connection emulation in your browser,
> start uploading a few files, cancel an upload which didn't start yet)
> Relevant changes with cancel demo:
> [https://github.com/andruhon/WicketDragAndDropFileAjaxUpload/commit/7eae49467655d8a0a4573e16f5e074688c8f12f6]
>
> I didn't find a way to cancel a request before it was actually sent,
> Imagine I do drag and drop of multiple files and jquery uploads them one by
> one. Normally with jQuery it is possible to return false from `beforeSend`
> handle to cancel the request, however it's not a case with wicket's `bsh`. I
> could do something like this:
> {code:javascript}
> Wicket.Ajax.ajax({
> u: myUrl,
> m: 'POST',
> mp: true,
> bsh: [
> function (attributes, jqXHR, settings) {
> settings.xhr = function () {
> try {
> if (uploadContext.cancelled) {
> // cancel upload
> return null;
> }
> if (uploadContext.item) {
> /* Add progress indicator */
> xhr.upload.addEventListener("progress",
> function (e) {
> var progress = Math.round(e.loaded /
> e.total * 100);
> onUploadProgress(uploadContext,
> attrs, progress);
> });
> }
> return xhr;
> } catch (e) {
> }
> }
> }
> ],
> {code}
> It does the trick, however it will cause the jQuery.send to explode with
> `Cannot read property 'open' of null`
> I'm not sure what the best way to do that, but probably `_executeHandlers`
> could return false if any of handlers returns false, something like this:
> {code:javascript}
> /**
> * A helper function that executes an array of handlers
> (before, success, failure)
> *
> * @param handlers {Array[Function]} - the handlers to execute
> * @private
> */
> _executeHandlers: function (handlers) {
> if (jQuery.isArray(handlers)) {
> // cut the handlers argument
> var args =
> Array.prototype.slice.call(arguments).slice(1);
> // assumes that the Ajax attributes is always
> the first argument
> var attrs = args[0];
> var that = this._getTarget(attrs);
> for (var i = 0; i < handlers.length; i++) {
> var handler = handlers[i];
> var r;
> if (jQuery.isFunction(handler)) {
> r = handler.apply(that, args);
> } else {
> r = new
> Function(handler).apply(that, args);
> }
> if (r === false) {
> return false;
> }
> }
> }
> },
> //...
> {code}
> and
> {code:javascript}
> // execute the request
> var jqXHR = jQuery.ajax({
> url: url,
> type: attrs.m,
> context: self,
> processData: wwwFormUrlEncoded,
> contentType: wwwFormUrlEncoded,
>
> beforeSend: function (jqXHR, settings) {
> if(self._executeHandlers(attrs.bsh,
> attrs, jqXHR, settings)===false) {
> return false;
> }
> we.publish(topic.AJAX_CALL_BEFORE_SEND,
> attrs, jqXHR, settings);
> if (attrs.i) {
> // show the indicator
>
> Wicket.DOM.showIncrementally(attrs.i);
> }
> },
> // ...
> {code}
> Preconditions checked before the jQuery.ajax is called, but what I say
> happens after, but before jQuery did actually start this request.
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