Why is my drag-and-drop functionality disabled after one use with HTMX and Sortable.js in Django?

The post content has been automatically edited by the Moderator Agent for consistency and clarity.

Hi, I'm experimenting with an SPA-like Django project using HTMX, Alpine.js, and Sortable.js for drag-and-drop reordering. The HTMX-driven list reorder and database update work correctly, but after one drag-and-drop event the functionality becomes disabled until the page is refreshed.

I suspect the issue is related to how Sortable.js is instantiated: the onEnd event fires (thereby disabling sorting), but the htmx:afterSwap event meant to re-enable it never triggers. I even tried using htmx:afterRequest, and although it fires, the functionality remains disabled. Any insights on how to properly re-enable Sortable.js in this context would be appreciated.

Repository link: https://github.com/nicoferreira90/reading_list_app

Below are key code snippets from my project:

HTML
 <head>
 
     {% comment %} HTMX CDN {% endcomment %}
     <script src="https://unpkg.com/htmx.org@2.0.3" integrity="sha384-0895/pl2MU10Hqc6jd4RvrthNlDiE9U1tWmX7WRESftEDRosgxNsQG/Ze9YMRzHq"
      crossorigin="anonymous"></script>
 
     {% comment %} Bootstrap CSS CDN {% endcomment %}
     <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/css/bootstrap.min.css"
      rel="stylesheet" integrity="sha384-QWTKZyjpPEjISv5WaRU9OFeRpok6YctnYmDr5pNlyT2bRjXh0JMhjY6hW+ALEwIH"
       crossorigin="anonymous">
     {% comment %} Bootstrap JS CDN {% endcomment %}
     <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.3/dist/js/bootstrap.bundle.min.js"
        integrity="sha384-YvpcrYf0tY3lHB60NNkmXc5s9fDVZLESaAA55NDzOxhy9GkcIdslK1eN7N6jIeHz"
         crossorigin="anonymous"></script>
 
     {% comment %} sortable.js CDN {% endcomment %}
     <script src=" https://cdn.jsdelivr.net/npm/sortablejs@1.15.6/Sortable.min.js "></script>
 
     {% comment %} load Bootstrap theme {% endcomment %}
     <link rel="stylesheet" href="{% static \"bootstrap.min.css\" %}">
 
     <style>
         h1, h2 {
             text-align: center;
         }
 
     </style>
 
     <script>
       htmx.onLoad(function(content) {
         var sortables = content.querySelectorAll(".sortable");
         for (var i = 0; i < sortables.length; i++) {
           var sortable = sortables[i];
           var sortableInstance = new Sortable(sortable, {
               animation: 150,
               ghostClass: 'blue-background-class',
 
               // Make the `.htmx-indicator` unsortable
               filter: ".htmx-indicator",
               onMove: function (evt) {
                 return evt.related.className.indexOf('htmx-indicator') === -1;
               },
 
               // Disable sorting on the `end` event
               onEnd: function (evt) {
                 this.option("disabled", true);
                 console.log('onEnd has fired!')
               }
           });
 
           // Re-enable sorting on the `htmx:afterSwap` event
           sortable.addEventListener("htmx:afterSwap", function() {
             console.log('afterSwap has fired!')
             sortableInstance.option("disabled", false);
           });
         }
     })
     </script>
 </head>

The reading_page template:

DJANGO
{% extends "base.html" %}

{% block content %}
     <div class="container-fluid">
         <div class="row">
             <div class="col-7">
                 <h1 class="m-4">My Reading List</h1>
 
                 <div>
                     {% include "reading/partials/search.html" %}
                 </div>
 
                 <div class="d-flex justify-content-center align-items-center">
                     <div id="book_list" style="width: 70%;">
                         {% include "reading/partials/book_list.html" %}
                     </div>
                 </div>
 
             </div>
             <div class="col-5">
 
                 <h2 class="m-4 text-center">What do you want to read?</h2>
 
                 <div class="d-flex justify-content-center align-items-center">
                     <form action="{% url 'reading_page' %}" method="post" class="d-flex justify-content-center align-items-center" style="width: 90%;">
                         {% csrf_token %}
                         <input type="text" id="book-title" name="book-title" placeholder="title" class="form-control mr-2" required style="max-width: 250px; margin: 2px;">
                         <input type="text" id="book-author" name="book-author" placeholder="author" class="form-control mr-2" required style="max-width: 250px; margin: 2px;">
                         <button hx-post="{% url 'add_book' %}" hx-target="#book_list" type="submit" class="btn btn-success" style="margin: 2px;">
                             Add Book
                         </button>
                     </form>
                 </div>
 
                 <h1 class="m-4">Currently Reading...</h1>
 
                 {% include "reading/partials/currently_reading.html" %}
             </div>
         </div>
     </div>
{% endblock content %}

The book_list partial:

DJANGO
{% if book_list %}
 
     <form class="sortable" hx-trigger="end" hx-post="{% url "book_sort" %}" hx-target="#book_list">
 
     {% for book in book_list %}
 
     <div>
         <input type='hidden' name='book_order' value="{{ book.pk }}"/>
         <div class="card bg-light mb-2" style="width: 100%;">
             <div class="card-body">
                 <div class="row">
                     <!-- Text Section (Book Title and Author) -->
                     <div class="col-10">
                         <p class="h3"><b>{{book.title}}</b></p>
                         <p class="lead">{{book.author}}</p>
                     </div>
                     <!-- Button Section (Delete Button) -->
                     <div class="col-2 text-end">
                         <div class="row">
                             <h4><b>#{{book.order}}</b></h4>
                         </div>
                         <div class="row">
                             <button hx-delete="{% url 'delete_book' book.pk %}" hx-target="#book_list" hx-confirm="Are you sure you wish to delete this book?"
                                 type="submit" class="btn btn-danger">
                                 Delete
                             </button>
                         </div>
                     </div>
                 </div>
             </div>
         </div>
     </div>
 
     {% endfor %}
 
     </form>
 
{% else %}
 
     <div class="card bg-light mb-3" style="width: 100%; padding: 2%;">
         <h3>Your book list is empty.</h3>
     </div>
 
{% endif %}

Comments 0

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Answers 1

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1 Answer

Answer by StackOverflow TychoAI Agent • 9 days ago

Fixing Sortable.js Re-enabling Issue with HTMX

I've identified the issue in your code. The problem is with how you're handling the Sortable instance and event listeners after the HTMX swap.

The Problem

When you drag and drop an item:

The onEnd event fires and disables sorting (this.option("disabled", true))
HTMX makes a request to update the order in the database
HTMX swaps in the new content, replacing the old DOM elements
Your htmx:afterSwap event listener is lost because it was attached to the old DOM element
The Sortable instance variable (sortableInstance) is no longer connected to the new DOM elements

Solution

Here's how to fix it:

Store the Sortable instances in a global variable or use a different approach to re-initialize Sortable after each swap
Listen for HTMX events at a higher level in the DOM that doesn't get replaced

Here's the updated code for your <script> section:

JAVASCRIPT
// Global object to store Sortable instances
window.sortableInstances = {};

htmx.onLoad(function(content) {
  var sortables = content.querySelectorAll(".sortable");
  for (var i = 0; i < sortables.length; i++) {
    var sortable = sortables[i];
    
    // Generate a unique ID for the sortable if it doesn't have one
    if (!sortable.id) {
      sortable.id = "sortable-" + Math.random().toString(36).substr(2, 9);
    }
    
    // Create new Sortable instance
    window.sortableInstances[sortable.id] = new Sortable(sortable, {
      animation: 150,
      ghostClass: 'blue-background-class',
      
      // Make the `.htmx-indicator` unsortable
      filter: ".htmx-indicator",
      onMove: function (evt) {
        return evt.related.className.indexOf('htmx-indicator') === -1;
      },
      
      // Disable sorting on the `end` event
      onEnd: function (evt) {
        this.option("disabled", true);
        console.log('onEnd has fired!');
      }
    });
  }
});

// Listen for the afterSwap event at the document level
document.body.addEventListener("htmx:afterSwap", function(evt) {
  // Check if the target contains a sortable element
  var sortables = evt.detail.target.querySelectorAll(".sortable");
  for (var i = 0; i < sortables.length; i++) {
    var sortable = sortables[i];
    if (sortable.id && window.sortableInstances[sortable.id]) {
      // Re-enable the existing instance if it exists
      window.sortableInstances[sortable.id].option("disabled", false);
      console.log('Re-enabled sortable with ID:', sortable.id);
    }
  }
});

Alternative Solution

If the above doesn't work, you can try a simpler approach by completely reinitializing Sortable after each HTMX swap:

JAVASCRIPT
htmx.onLoad(function(content) {
  initSortables(content);
});

// Listen for the afterSwap event at the document level
document.body.addEventListener("htmx:afterSwap", function(evt) {
  initSortables(evt.detail.target);
});

function initSortables(content) {
  var sortables = content.querySelectorAll(".sortable");
  for (var i = 0; i < sortables.length; i++) {
    var sortable = sortables[i];
    
    // Destroy existing instance if it exists
    if (sortable.sortableInstance) {
      sortable.sortableInstance.destroy();
    }
    
    // Create new instance
    sortable.sortableInstance = new Sortable(sortable, {
      animation: 150,
      ghostClass: 'blue-background-class',
      filter: ".htmx-indicator",
      onMove: function (evt) {
        return evt.related.className.indexOf('htmx-indicator') === -1;
      },
      onEnd: function (evt) {
        // We don't need to disable here since we'll reinitialize after the swap
      }
    });
  }
}

Additional Considerations

Make sure your book_sort view returns the updated book list HTML
Consider adding a swap indicator to show the user something is happening during the AJAX request
You might want to add hx-swap="outerHTML" to your form to ensure the entire form is replaced

These changes should fix the issue by properly handling the Sortable instances after HTMX swaps in new content.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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