Contrib

These components are not directly part of the GOV.UK Design System but are used often in many applications and services.

E.g. EmailInput and GBPInput can be used in forms to collect emails and GBP values. NumberInput and DecimalInput can be used to validate if the user filled-in an integer or a decimal number in a field. PastDateInput and FutureDateInput can validate if the date entered by the user is in the past and the future respectively etc.

This module also serves as an example on how to extend/modify the base fields.

class fast_gov_uk.design_system.contrib.EmailInput(*args, width: InputWidth = InputWidth.DEFAULT, prefix: str = '', suffix: str = '', autocomplete: str = '', numeric: bool = False, spellcheck: bool = False, extra_spacing: bool = False, **kwargs)

Bases: TextInput

GOV.UK TextInput component with some basic email validation using Python’s built-in email.utils.parseaddr.

If your workflow needs to ensure that the email actually belongs to the user, you might want to send them a confirmation email etc.

Examples

>>> email = ds.EmailInput("email")
>>> email.value = "test"
>>> email.error
'Value is not an email'
>>> email.value = "test@test"
>>> email.error
''
class fast_gov_uk.design_system.contrib.NumberInput(*args, numeric: bool = True, **kwargs)

Bases: TextInput

GOV.UK TextInput component that validates number input using the int() typecast.

Examples

>>> number = ds.NumberInput("number")
>>> number.value = "x"
>>> number.error
'Value is not an number'
>>> number.value = "3.4"
>>> number.error
'Value is not an number'
>>> number.value = "10"
>>> number.error
''
property clean

Get “clean” data from a field when a form is being processed by a form Backend.

class fast_gov_uk.design_system.contrib.DecimalInput(*args, numeric: bool = True, **kwargs)

Bases: TextInput

GOV.UK TextInput component that validates decimal input using the float() typecast.

Examples

>>> decimal = ds.DecimalInput("decimal")
>>> decimal.value = "x"
>>> decimal.error
'Value is not an number'
>>> decimal.value = "10"
>>> decimal.error
''
>>> decimal.value = "3.4"
>>> decimal.error
''
property clean

Get “clean” data from a field when a form is being processed by a form Backend.

class fast_gov_uk.design_system.contrib.GBPInput(*args, prefix: str = '£', **kwargs)

Bases: DecimalInput

A DecimalInput with a currency prefix, commonly used for GBP (£) field in GOV.UK services.

Examples

>>> gbp = ds.GBPInput("gbp")
# Input with £ prefix: £ ____
>>> gbp.value = "x"
>>> gbp.error
'Value is not an number'
>>> gbp.value = "10"
>>> gbp.error
''
>>> gbp.value = "3.4"
>>> gbp.error
''
fast_gov_uk.design_system.contrib.BackLinkJS(text: str = 'Back', inverse: bool = False) → FT

An implmentation of GOV.UK back link component that uses JavaScript to go back one page in the browser.

This is often useful in cases where it is clunky to maintain state for the current step in a multi-step journey on the server.

Note that this would not work if a user has javascript disabled in their browser.

Examples

>>> back = ds.BackLinkJS()
>>> str(back)
'<a href="javascript:history.back()" class="govuk-back-link">Back</a>'
Parameters:

  • text (str, optional) – The text for the backlink. Defaults to “Back”.

  • inverse (bool, optional) – Use inverse style. Defaults to False.

Returns:

A FastHTML BackLink component.

Return type:

FT

class fast_gov_uk.design_system.contrib.RegexInput(*args, regex: str = '.*', **kwargs)

Bases: TextInput

GOV.UK TextInput component that accepts a regex string to validate user input.

This can be handy for e.g. postcodes - https://stackoverflow.com/a/69806181/1182202.

Examples

>>> re = ds.RegexInput("postcode", regex="(blue|white|red)")
>>> re.value="white"
>>> re.error
''
>>> re.value="green"
>>> re.error
'Value does not match the required format.'
class fast_gov_uk.design_system.contrib.PastDateInput(*args, **kwargs)

Bases: DateInput

GOV.UK DateInput component that only accepts a date in the past.

This is useful for collecting date of birth etc.

Examples

>>> past = ds.PastDateInput("past")
>>> past.value=["1", "1", "2000"]
>>> past.error
''
>>> past.value = ["1", "1", "3000"]
>>> past.error
'The date must be in the past.'
class fast_gov_uk.design_system.contrib.FutureDateInput(*args, **kwargs)

Bases: DateInput

GOV.UK DateInput component that only accepts a date in the future.

This is useful for when a service allows users to e.g. booking something in advance.

Examples

>>> future = ds.FutureDateInput("future")
>>> future.value = ["1", "1", "3000"]
>>> future.error
''
>>> future.value=["1", "1", "2000"]
>>> future.error
'The date must be in the future.'