Django Convenient Formsets

This Django app aims to make dynamic formsets convenient for users and developers alike. It extends Django's built-in formset classes and includes support for adding, deleting and ordering of forms in the browser. JavaScript events are dispatched when forms are added, deleted or reordered, for executing custom logic.

Supported platforms

Django: 4.2+
Python: 3.8+
Tested desktop browsers: latest Chrome, latest Firefox, latest Edge, latest Opera, latest Safari

Other platform versions may work, but are not actively tested.

Installation

Install using pip:

$ pip install django-convenient-formsets

Add to INSTALLED_APPS:

INSTALLED_APPS = [
    # ...
    'convenient_formsets'
]

Quick start

Create a formset in your Python code:

from convenient_formsets import ConvenientBaseFormSet
from django import forms


class EmailForm(forms.Form):
    email = forms.EmailField()

EmailFormSet = forms.formset_factory(
    EmailForm,
    formset=ConvenientBaseFormSet,
    can_delete=True,
    can_order=True,
)

email_formset = EmailFormSet(prefix='email-formset')

Render formset in your template and add JavaScript code for initialization:

<!doctype html>
<html>
<head>
    <!-- Include the formset's media -->
    {{ email_formset.media }}

    <!-- Initialize a ConvenientFormset -->
    <script>
        window.addEventListener('load', function(event) {
            new ConvenientFormset({
                'formsetPrefix': '{{ email_formset.prefix }}',
                'formsContainerSelector': '#email-formset #email-forms-container',
                'formSelector': '.email-form',

                'canAddForms': true,
                'addFormButtonSelector': '#email-formset #add-form-button',
                'emptyFormTemplateSelector': '#email-formset #empty-form-template',

                'canDeleteForms': true,
                'deleteFormButtonSelector': '.delete-form-button',

                'canOrderForms': true,
                'moveFormDownButtonSelector': '.move-form-down-button',
                'moveFormUpButtonSelector': '.move-form-up-button',
            });
        });
    </script>
</head>

<body>
    <!-- Render formset using the following basic structure -->
    <div id="email-formset">
        <div id="email-forms-container">
            {% for email_form in email_formset.forms %}
            <div class="email-form">
                {{ email_form.email }}
                {% if email_formset.can_delete %}
                    {{ email_form.DELETE }}
                    <input type="button" class="delete-form-button" value="Delete">
                {% endif %}
                {% if email_formset.can_order %}
                    {{ email_form.ORDER }}
                    <input type="button" class="move-form-up-button" value="Move up">
                    <input type="button" class="move-form-down-button" value="Move down">
                {% endif %}
            </div>
            {% endfor %}
        </div>
        <div><input type="button" id="add-form-button" value="Add another"></div>
        <template id="empty-form-template">
            <div class="email-form">
                {{ email_formset.empty_form.email }}
                {% if email_formset.can_delete %}
                    <input type="button" class="delete-form-button" value="Delete">
                {% endif %}
                {% if email_formset.can_order %}
                    {{ email_form.ORDER }}
                    <input type="button" class="move-form-up-button" value="Move up">
                    <input type="button" class="move-form-down-button" value="Move down">
                {% endif %}
            </div>
        </template>
        {{ email_formset.management_form }}
    </div>
</body>
</html>

Usage

Server side

The Python classes ConvenientBaseFormSet, ConvenientBaseModelFormSet and ConvenientBaseInlineFormSet extend Django's built-in BaseFormSet, BaseModelFormSet and BaseInlineFormSet by:

Overriding deletion_widget for the DELETE field and ordering_widget for the ORDER field. They default to the forms.HiddenInput widget in order to hide them from the user.
Including the JavaScript file in the formset's media attribute required for dynamic formsets.

Client side

See the example in the Quick start guide above on how to render the formset in your HTML template. Feel free to add some intermediate DOM elements if it suits your template better, as long as you stick to the basic structure shown above.

It is important that both the visible forms and the empty form follow the same structure. A form also needs to be contained inside a single parent element, denoted by the formSelector parameter:

<!-- Visible forms inside forms container -->
<div id="email-forms-container">
    <div class="email-form">
        <!-- Form -->
    </div>
</div>

<!-- Empty form inside template element -->
<template id="empty-form-template">
    <div class="email-form">
        <!-- Form -->
    </div>
</template>

Configuration

Creating an instance of the JavaScript constructor function ConvenientFormset allows a user to add, delete and reorder forms within the rendered formset. When a user makes changes, the management form is updated accordingly. The constructor function can be passed the parameters outlined below. In case initialization fails, check the browser console for some helpful output.

GENERAL

formsetPrefix: The formset's "prefix" attribute (required).
formsContainerSelector: CSS selector for the DOM element that contains all the forms (required).
formSelector: CSS selector for each form within "formsContainerSelector" (required).

ADDING FORMS

canAddForms: Enables adding of new forms (default: true).
addFormButtonSelector: CSS selector for the DOM element that may be clicked to add an empty form (required if "canAddForms" is set).
emptyFormTemplateSelector: CSS selector for the empty form <template> element (required if "canAddForms" is set).
hideAddFormButtonOnMaxForms: Hides the add button when reaching the maximum number of forms, by applying the "hidden" HTML attribute (default: true).

DELETING FORMS

canDeleteForms: Enables deleting of forms (default: false).
deleteFormButtonSelector: CSS selector for the DOM element within "formSelector" that may be clicked to delete a form (required if "canDeleteForms" is set).

ORDERING FORMS

canOrderForms: Enables ordering of forms (default: false).
moveFormDownButtonSelector: CSS selector for the DOM element within "formSelector" that may be clicked to move a form down among the visible forms (required if "canOrderForms" is set).
moveFormUpButtonSelector: CSS selector for the DOM element within "formSelector" that may be clicked to move a form up among the visible forms (required if "canOrderForms" is set).

Events

When adding, deleting or reordering forms, custom JavaScript events are dispatched to allow for executing custom JavaScript code:

convenient_formset:added: Dispatched when a form is added to the formset.
convenient_formset:removed: Dispatched when a form is removed to the formset.
convenient_formset:movedDown: Dispatched when a form is moved downwards while reordering forms inside the formset.
convenient_formset:movedUp: Dispatched when a form is moved upwards while reordering forms inside the formset.

All events will contain the formsetPrefix parameter value in the event's detail property.

These events can be handled in the following way:

document.addEventListener('convenient_formset:added', (event) => {
    if (event.detail.formsetPrefix === 'email-formset') {
        // Handle event for a specific formset on the webpage
    }
});

document.addEventListener('convenient_formset:removed', (event) => {
    // Handle event for any formset on the webpage
});

Internals

Form deletion is handled in either of the following ways:

If a form includes a DELETE field, the field's value is updated and the form will be hidden by applying the "hidden" HTML attribute. The deletion will then be handled server side.
If the form does not include a DELETE field, the form is removed from the DOM altogether and will not be submitted to the server.

Form ordering is handled by moving visible forms above the previous (up) and below the next (down) for visual feedback, and by swapping the values of their ORDER fields for the server side. This means that the original values are kept, even when in-between forms are deleted. New forms will see the initial value for their ORDER field set to the last visible form's ORDER field value + 1, as they're added to the bottom of all forms.

License

The scripts and documentation in this project are released under the BSD-3-Clause License.

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