django-formset

A FormCollection is considered a collection with siblings if it defines any of the following attributes:

• min_siblings: The minimum number of collections required (defaults to 1).
• max_siblings: The maximum number of collections allowed (no limit by default).
• extra_siblings: The number of empty collections to start with (defaults to 0).

Collections with siblings allow users to add or remove multiple instances of a collection. For each collection with siblings, there is one "Add" button, and each child collection has a "Remove" button (which is invisible by default and appears on hover).

class MyCollection(FormCollection):
    min_siblings = 1
    max_siblings = 5
    extra_siblings = 2
    # ... fields ...

A formset can group multiple forms into a collection, and these collections can be nested.

Submission Behavior: When a formset is submitted, the data from the forms or collections is sent to the server as a group of separate entities.

Dynamic Collections: Form-collections can be configured to have "list siblings." These can be dynamically adjusted in length using:

• An "Add" button to increase the number of forms.
• Multiple "Remove" buttons to decrease the number of forms.

While technically possible to submit multiple forms in a single HTTP request, it is generally discouraged because it can lead to data handling complexities on the server and conflicts with overlapping field names.

Recommended approaches:

1. Combine data from different forms into a single, unified form.
2. Submit each form separately in its own request.
3. Use JavaScript to collect data from multiple forms and combine them into a single request payload if they must be sent together.

You can conditionally hide, show, or disable fields or fieldsets based on the current values of other fields in the formset. This is done by adding special attributes to the input fields or fieldsets. The condition argument accepts an expression that evaluates the current field values.

Supported attributes:

• df-show="condition"
• df-hide="condition"
• df-disable="condition"

The library provides enhanced widgets to improve UX:

• Autocomplete Select: Replaces the standard <select> with an autocomplete version. It uses the same endpoint as the formset, so no extra URL routing is required.
• Multi-Select Widgets: Offers two modes: one that keeps selected options inlined, and another that uses a 'source' and 'target' (dual-selector) pattern. The dual-selector supports database querying for large datasets, filtering, undo/redo, and optional sorting of selected items.
• Asynchronous File Upload: Provides a drag-and-drop widget that uploads files asynchronously. This allows for file previews and faster form submissions since files are uploaded to a temporary server location before the final form submission.

Choosing between DualSelector and SelectizeMultiple depends on the expected number of selections and available UI space:

Both widgets share the same lookup interface and can be swapped by changing the widget argument in the field or via the form's Meta class.

The submission button in django-formset can hold a chain of actions. This allows you to define behaviors such as:

• Disabling the button upon click.
• Adding a spinning loading indicator during submission.
• Specifying a success page via an HTML link directly in the button configuration, rather than hard-coding it in the Django view.

The richtext-selection attribute is used to map the editor's currently selected text to a dialog form field. This is typically used when a user selects text and then triggers an extension (like a hyperlink) to ensure the selected text is automatically populated as the initial value in the dialog (e.g., the 'Link Text' field).

text = fields.CharField(
    label="Link Text",
    widget=widgets.TextInput(attrs={
        'richtext-selection': True,
        'size': 50,
    })
)