tbxforms 3.0.0

A Torchbox-flavoured template pack for django-crispy-forms, adapted from crispy-forms-gds

Torchbox Forms

A Torchbox-flavoured template pack for django-crispy-forms, adapted from crispy-forms-gds.

Out of the box, forms created with tbxforms will look like the GOV.UK Design System, though many variables can be customised.

Requirements

• python >=3.8.1,<4.0
• Django >=3.2
• django-crispy-forms >=2.1,<3.0
• wagtail >=2.15 if using WagtailBaseForm
• sass >=1.33.0 if building the sass yourself

[!NOTE] govuk-frontend will not, and does not need to, be installed to use this package.

All form-related styles from govuk-frontend==5.4.1 have been copied into this project with the prepended "govuk-" replaced with "tbxforms-", e.g. .govuk-button to .tbxforms-button and @mixin govuk-clearfix to @mixin tbxforms-clearfix.

For non-government projects, installing the complete GOV.UK Frontend package unnecessarily increases the bundle size as we only need form-related styles.

For government projects, this increases the bundle size as both tbxforms and govuk-frontend must be installed. However, these projects are less common, so they are not prioritised.

Installation

You must install both the Python package and the NPM package.

Install the Python package

Install using pip:

pip install tbxforms

Add django-crispy-forms and tbxforms to your installed apps:

INSTALLED_APPS = [
  # ...
  'crispy_forms',  # django-crispy-forms
  'tbxforms',
]

Now add the following settings to tell django-crispy-forms to use tbxforms:

CRISPY_ALLOWED_TEMPLATE_PACKS = ["tbx"]
CRISPY_TEMPLATE_PACK = "tbx"

Install the NPM package

Install using NPM:

npm install tbxforms

Note: This package uses the Element.closest, NodeList.forEach, and Array.includes APIs. You will need to install and configure polyfills for legacy browser support if you need to.

Instantiate your forms:

import TbxForms from 'tbxforms';

document.addEventListener('DOMContentLoaded', () => {
    for (const form of document.querySelectorAll(TbxForms.selector())) {
        new TbxForms(form);
    }
});

Import the styles into your project...

...Either as CSS without any customisations:

@use 'node_modules/tbxforms/dist/style.css';

...Or as Sass to customise variables:

@use 'node_modules/tbxforms/tbxforms.scss' with (
    $tbxforms-text-colour: #000,
    $tbxforms-error-colour: #f00,
);

Add button styles

tbxforms provides out-of-the-box GOV.UK Design System styles for everything except buttons, as styles for these probably exist within your project.

You will need to write button styles for the following classes:

1. .tbxforms-button
2. .tbxforms-button.tbxforms-button--primary
3. .tbxforms-button.tbxforms-button--secondary
4. .tbxforms-button.tbxforms-button--warning

Usage

tbxforms can be used for coded Django forms and editor-controlled Wagtail forms.

Django forms

All forms must inherit the TbxFormsMixin mixin, as well as specifying a Django base form class (e.g. forms.Form or forms.ModelForm)

from django import forms
from tbxforms.forms import TbxFormsMixin

class ExampleForm(TbxFormsMixin, forms.Form):
    ...

class ExampleModelForm(TbxFormsMixin, forms.ModelForm):
    ...

Wagtail forms

Create or update a Wagtail form

Wagtail forms must inherit from TbxFormsMixin and WagtailBaseForm.

from wagtail.contrib.forms.forms import BaseForm as WagtailBaseForm
from tbxforms.forms import TbxFormsMixin

class ExampleWagtailForm(TbxFormsMixin, WagtailBaseForm):
    ...

Instruct a Wagtail Page model to use your form

In your form definitions (e.g. forms.py):

from tbxforms.forms import BaseWagtailFormBuilder as TbxFormsBaseWagtailFormBuilder
from path.to.your.forms import ExampleWagtailForm

class WagtailFormBuilder(TbxFormsBaseWagtailFormBuilder):
    def get_form_class(self):
        return type(str("WagtailForm"), (ExampleWagtailForm,), self.formfields)

And in your form page models (e.g. models.py):

from path.to.your.forms import WagtailFormBuilder

class ExampleFormPage(...):
    ...
    form_builder = WagtailFormBuilder
    ...

Render a form

Just like Django Crispy Forms, you need to pass your form object to the {% crispy ... %} template tag, e.g.:

{% load crispy_forms_tags %}

<html>
    <body>
        {% crispy your_sexy_form %}
    </body>
</html>

FormHelpers

A FormHelper allows you to alter the rendering behaviour of forms.

Every form that inherits from TbxFormsMixin (i.e. every form within tbxforms) will have a FormHelper with the following default attributes:

• html5_required = True
• label_size = Size.MEDIUM
• legend_size = Size.MEDIUM
• form_error_title = _("There is a problem with your submission")
• Plus everything from django-crispy-forms' default attributes.

These can be changed during instantiation or on the go - examples below.

Add a submit button

Submit buttons are not automatically added to forms. To add one, you can extend the form.helper.layout (examples below).

Extend during instantiation:

from django import forms
from tbxforms.forms import TbxFormsMixin
from tbxforms.layout import Button

class YourSexyForm(TbxFormsMixin, forms.Form):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.helper.layout.extend([
            Button.primary(
                name="submit",
                type="submit",
                value="Submit",
            )
        ])

Or afterwards:

from tbxforms.layout import Button

form = YourSexyForm()
form.helper.layout.extend([
    Button.primary(
        name="submit",
        type="submit",
        value="Submit",
    )
])

Conditionally-required fields

tbxforms can show/hide parts of the layout depending on a given value. For example, you could show (and require) an email address field only when the user chooses to sign up to a newsletter (examples below).

You can apply this logic to field, div, and fieldset elements.

Note: any field names included within the conditional_fields_to_show_as_required() method will appear on the frontend as required, though will technically be required=False.

Field example:

from django import forms
from django.core.exceptions import ValidationError
from tbxforms.choices import Choice
from tbxforms.forms import TbxFormsMixin
from tbxforms.layout import Field, Layout

class ExampleForm(TbxFormsMixin, forms.Form):
    NEWSLETTER_CHOICES = (
        Choice("yes", "Yes please", hint="Receive occasional email newsletters."),
        Choice("no", "No thanks"),
    )

    newsletter_signup = forms.ChoiceField(
        choices=NEWSLETTER_CHOICES
    )

    email = forms.EmailField(
        widget=forms.EmailInput(required=False)
    )

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.helper.layout = Layout(
            # Add our newsletter sign-up field.
            Field.text("newsletter_signup"),

            # Add our email field and define the conditional logic.
            Field.text(
                "email",
                data_conditional={
                    "field_name": "newsletter_signup", # Field to inspect.
                    "values": ["yes"], # Value(s) to cause this field to show.
                },
            ),
        )

    @staticmethod
    def conditional_fields_to_show_as_required() -> [str]:
        # Non-required fields that should show as required to the user.
        return [
            "email",
        ]

    def clean(self):
        cleaned_data = super().clean()
        newsletter_signup = cleaned_data.get("newsletter_signup")
        email = cleaned_data.get("email")

        # Fields included within `conditional_fields_to_show_as_required()` will
        # be shown as required but not enforced - i.e. they will not have the
        # HTML5 `required` attribute set.
        # Thus we need to write our own check to enforce the value exists.
        if newsletter_signup == "yes" and not email:
            raise ValidationError(
                {
                    "email": "This field is required.",
                }
            )
        # The tbxforms JS will attempt to clear any redundant data upon submission,
        # though it is recommended to also handle this in your clean() method.
        elif newsletter_signup == "no" and email:
            del cleaned_data['email']

        return cleaned_data

Container example:

When you have multiple fields/elements that you want to show/hide together, you can use the exact same data_conditional definition as above but on a div or fieldset element, e.g.:

from tbxforms.layout import HTML, Div, Field, Layout

Layout(
    Div(
        HTML("<p>Some relevant text.</p>"),
        Field.text("some_other_field"),
        Field.text("email"),
        data_conditional={
            "field_name": "newsletter_signup",
            "values": ["yes"],
        },
    ),
)

Customising behaviour

Highlight required fields instead of optional ones

If TBXFORMS_HIGHLIGHT_REQUIRED_FIELDS=False (or unset), optional fields will have "(optional)" appended to their labels. This is the default behaviour and recommended by GDS.

If TBXFORMS_HIGHLIGHT_REQUIRED_FIELDS=True, required fields will have an asterisk appended to their labels and optional fields will not be highlighted.

You can also style these markers by targeting these CSS classes:

• .tbxforms-field_marker--required
• .tbxforms-field_marker--optional

Change the default label and legend classes

Possible values for the label_size and legend_size:

1. SMALL
2. MEDIUM (default)
3. LARGE
4. EXTRA_LARGE

Further reading

• Download the PyPI package
• Download the NPM package
• Learn more about Django Crispy Forms
• Learn more about Crispy Forms GDS
• Learn more about GOV.UK Design System