how can I reset a blueimp jQuery fileupload plugin?

Question

The gist: how can I reset a blueimp jQuery fileupload plugin so that it thinks no files have been uploaded already?

My Scenario

• I have an upload form that only allows one file to be uploaded.
• Once that file is uploaded, it is analyzed. At this point, the user has the option to click a "cancel" button, where I reset the rest of my viewmodel.
• When the user clicks cancel, I would like to reset the count of files the user has uploaded, because they're essentially starting fresh.
• I still want the one file maximum to apply after reset.

What happens currently

• Upload a file
• Click the cancel button, everything resets (i.e. I re-initialize the file upload control)
• Attempt to upload a file and am still told the number of max files has been reached.

What I've Tried

I tried calling fileupload('destroy') and then reinitializing, but that appeared to have no result (I was hoping that destroying would also tear down the tracking of the instance).

My question(s):

• What is the best way to destroy/re-initialize/reset the upload control as if it's being started from scratch?
• If there is none, is there any way to programmatically make blueimp think that zero files have been uploaded after one already has, to effectively reset it? Thanks in advance for any help you can give!

A note on version:

FYI, I am on v8.8.1 -- I would prefer not to upgrade because a colleague changed some of the code in a specific way -- ugh. We plan to remove this customization and upgrade but at a scheduled date. If I have to update to resolve this, feel free to let me know because that's completely fair.

Update: Some Code

The first file upload control on the page:

<form id="summaryFileUploadForm" action="/api/InvoiceDetailsFile/PostForProcessing" method="POST"
    enctype="multipart/form-data" data-bind="disableFileUpload: InvoiceHasSummaryDocument() || (!InvoiceDataIsFilledIn())">

    <div class="fileupload-buttonbar">
        <div class="fileupload-buttons">

            <!-- The fileinput-button span is used to style the file input field as button -->
            <span class="fileinput-button">
                <span>Add files...</span>
                <input id="file" type="file" name="file" />
            </span>

            <span class="fileupload-loading"></span>
        </div>
        <!-- The global progress information -->
        <div class="fileupload-progress fade" style="display: none">
            <!-- The global progress bar -->
            <div class="progress" role="progressbar" aria-valuemin="0" aria-valuemax="100"></div>
            <!-- The extended global progress information -->
            <div class="progress-extended">&nbsp;</div>
        </div>
    </div>
    <div data-bind="fadeVisible: InvoiceHasSummaryDocument()">
        <span class="ui-icon ui-icon-check float-left"></span><span>A summary document has been uploaded.</span>
    </div>
    <span data-bind="fadeVisible: (!InvoiceDataIsFilledIn())">Please fill out invoice information before uploading a file.</span>
    <!-- The table listing the files available for upload/download -->
    <table role="presentation">
        <tbody class="files" id="Tbody1"></tbody>
    </table>

    <script id="summaryFileDownloadTemplate" type="text/x-tmpl">

    </script>
</form>

The second file upload control on the page:

<form id="detailsFileUploadForm" action="/api/InvoiceDetailsFile/PostForProcessing" method="POST"
    enctype="multipart/form-data" data-bind="disableFileUpload: Invoice().DetailItems().length > 0 || (!InvoiceHasSummaryDocument())">

    <div class="fileupload-buttonbar">
        <div class="fileupload-buttons">

            <!-- The fileinput-button span is used to style the file input field as button -->
            <span class="fileinput-button">
                <span>Add files...</span>
                <input id="file" type="file" name="file" />
            </span>

            <span class="fileupload-loading"></span>
        </div>
        <!-- The global progress information -->
        <div class="fileupload-progress fade" style="display: none">
            <!-- The global progress bar -->
            <div class="progress" role="progressbar" aria-valuemin="0" aria-valuemax="100"></div>
            <!-- The extended global progress information -->
            <div class="progress-extended">&nbsp;</div>
        </div>
    </div>
    <span><strong>NOTE: </strong>Only Excel 2007+ (.xlsx) files are accepted. <a href="<%= ResolveUrl("~/asset/xlsx/Ligado_InvoiceUploadTemplate_Standard.xlsx") %>" target="_blank" id="A1">Need a blank Invoice Upload template?</a><br />
    </span>
    <span data-bind="fadeVisible: Invoice().DetailItems().length > 0">Invoice details have been uploaded.</span>
    <span data-bind="fadeVisible: (!InvoiceHasSummaryDocument())">Please upload a summary file prior to uploading a details file.</span>

    <!-- The table listing the files available for upload/download -->
    <table role="presentation">
        <tbody class="files" id="fileList"></tbody>
    </table>
    <script id="template-upload" type="text/x-tmpl">
{% for (var i=0, file; file=o.files[i]; i++) { %}
    <tr class="template-upload fade" style="display:none">
        <td>
            <span class="preview"></span>
        </td>
        <td>
            <p class="name">{%=file.name%}</p>
            {% if (file.error) { %}
                <div><span class="error">Error:</span> {%=file.error%}</div>
            {% } %}
        </td>
        <td>
            <p class="size">{%=o.formatFileSize(file.size)%}</p>
            {% if (!o.files.error) { %}
                <div class="progress" role="progressbar" aria-valuemin="0" aria-valuemax="100" aria-valuenow="0"></div>
            {% } %}
        </td>
        <td>
            {% if (!o.files.error && !i && !o.options.autoUpload) { %}
                <button class="start">Start</button>
            {% } %}
            {% if (!i) { %}
                <button class="cancel">Cancel</button>
            {% } %}
        </td>
    </tr>
{% } %}
    </script>

    <script id="template-download" type="text/x-tmpl">

    </script>
</form>

I'm able to clear the first control using:

    $("tbody.files").empty();

presumably because the file has already been uploaded at that point (which is fine).

However, this doesn't work for the second form. I have tried:

    $("#detailsFileUploadForm").find('.cancel').click();

This makes the items disappear from the page, but they reappear when an additional file is added.

I have also tried $("#detailsFileUploadForm").fileupload('destroy') with no success (presumably because it does not handle these functions and is more about bindings.

Answer 1

The answer to this was a lot simpler than I expected:

$("table tbody.files").empty();

Previously, I think I was doing too much -- attempting to destroy/reset the container didn't work as well.

With this one line of code, the lists appear to reset and all is working well as far as I can tell.