Getting Input#

bootstack has a field widget for every common kind of value — text, numbers, dates, choices, on/off flags. They all share one idea: a field holds a value you can read at any time, and you can bind that value to a Signal so it stays in sync with the rest of your app without manual callbacks.

This guide covers reading and binding values. To check what the user typed, see Validation; to react to changes as they happen, see Handling Actions.

Text#

TextField is the single-line text input. Read the current string from .value; seed it with a positional argument and add a placeholder= for the empty hint:

name = bs.TextField("Ada", placeholder="Your name", label="Name")
print(name.value)        # "Ada"

For longer text use TextArea, for hidden entry PasswordField (with a built-in show/hide toggle), and for source or config text CodeEditor. All three expose the same .value string.

Numbers#

NumberField parses what the user types into an int or float, clamps it to min_value / max_value, and steps by step with its +/− buttons. .value is the parsed number (or None when the field is empty):

qty = bs.NumberField(value=1, min_value=1, max_value=99, step=1, label="Quantity")
price = bs.NumberField(value=9.99, min_value=0, step=0.5, label="Price")

Use an integer value/step for whole numbers and a float for fractional ones — the field follows the type you give it.

Dates and times#

DateField and TimeField return real datetime.date and datetime.time objects from .value, never strings. A date field carries a calendar popup; a time field offers a dropdown of times. Both accept constraints:

from datetime import date

when = bs.DateField(value=date.today(), min_date=date.today(), label="Ship date")
at = bs.TimeField(value=None, interval=15, label="Reminder")

print(when.value)        # datetime.date(2026, 6, 14)

Choices#

For a single choice from a list, the widget depends on how much room you have and how many options there are:

RadioGroup — a few options, all visible at once.
Select — a dropdown; searchable=True filters as you type.
SelectButton — a compact button that opens a menu.

Options can be plain strings, or (label, value) tuples when the text shown differs from the value you store. .value is always the value; .text is the visible label:

size = bs.RadioGroup(["Small", "Medium", "Large"], value="Medium", title="Size")

theme = bs.Select(
    options=[("Light theme", "light"), ("Dark theme", "dark")],
    value="light",
    label="Theme",
)
print(theme.value, theme.text)   # "light" "Light theme"

For multiple choices, use ToggleGroup with mode="multi" (its .value is a set), or a column of Checkbox widgets.

Sliders#

Slider picks a number on a track — handy when the rough magnitude matters more than an exact figure. RangeSlider picks a low/high pair:

volume = bs.Slider(value=50, min_value=0, max_value=100, show_value=True)
price_range = bs.RangeSlider(low_value=20, high_value=80, min_value=0, max_value=100)

print(volume.value)              # 50.0
print(price_range.value)         # (20.0, 80.0)

On/off#

Checkbox and Switch are boolean controls — .value is True or False. A Switch reads as an immediate setting (Wi-Fi on/off); a Checkbox reads as a selection you confirm later (terms accepted). ToggleButton is the same idea styled as a pressable button.

notify = bs.Switch("Email notifications", value=True)
agree = bs.Checkbox("I accept the terms")

Binding values with signals#

Reading .value on demand is fine for a submit button. But when the same value drives several widgets — a live preview, a summary label, a dependent control — bind it to a Signal instead. Every widget bound to the same signal updates together, in both directions.

Text-bearing fields use textsignal=; everything with a typed value uses signal=:

with bs.App(title="Live preview", padding=16, gap=8) as app:
    name = bs.Signal("World")
    bs.TextField(textsignal=name, placeholder="Type a name…")
    bs.Label(textsignal=name, font="heading-md", accent="primary")

app.run()

NumberField, DateField, and TimeField bind their typed value through signal= — the signal holds an int/float, a date, or a time, not the formatted text:

from datetime import date

count = bs.Signal(0)
bs.NumberField(signal=count, min_value=0)
bs.Label(textsignal=count.map(lambda n: f"{n} items"))   # derived label

day = bs.Signal(date.today())
bs.DateField(signal=day)

Boolean and choice controls bind through signal= as well — a Checkbox to a Signal(bool), a RadioGroup to a Signal holding the selected value. See Signals for deriving and combining signals.

Note

When you pass both signal= and an initial value= to a boolean control, the signal wins — seed the value on the signal itself (bs.Signal(True)), not on the widget.