Primefaces - Get files in alphabetical order in multiple file upload component - jsf

Question

I am using Primefaces Multiple file upload component in an application. Here i choose 'n' number of files and clicked on upload button. Then i need to get each files in fileUploadListener according to alphabetical order. How it possible?

Answer 1

As the multiple file upload component is a jQuery-File-Upload plugin, the default state is not sequential, that means all the files get upload asynchronously.
To get the component to do a sequential upload, you have to set sequentialUploads to true, and on change we do a little alphabetical sorting of the current files. all this is done by javascript.
Assuming your widgetVar is fileUploadWV
<p:fileUpload widgetVar="fileUploadWV"
fileUploadListener="#{attachmentBean.onUpload}" />
<script>
$(function() {
// setTimeout waits till the widgetVar is ready!
setTimeout(sortFileUpload, 2000);
});
function sortFileUpload() {
//Set this option to true to issue all file upload requests in a sequential order instead of simultaneous requests.
PF('fileUploadWV').jq.data().blueimpFileupload.options.sequentialUploads = true;
//every time a new file is added, sort the files based on name
PF('fileUploadWV').jq.change(function() {
PF('fileUploadWV').files.sort(function fileSort(a, b) {
return a.name.localeCompare(b.name)
})
});
}
</script>
So in this scenario your files would get uploaded in an alphabetical order.
Note: if you don't set sequentialUploads into true, you have no control which file is going to be sent first.
Github, Online Demo
Hope this helps.

Answer 2

yes, but this solution is not very elegant:
<p:remoteCommand action="#{attachmentBean.processAttachments}"
name="processAttachments" update="attachmentTable"/>
<p:fileUpload fileUploadListener="#{attachmentBean.onUpload}"
oncomplete="processAttachments()" />
attachmentBean.onUpload stores each file inside a List/Map/SortedMap
attachmentBean.processAttachments eventually sorts that List/Map and process attachments in order
attachmentBean must be at least #ViewScoped