Source code for wtforms.fields.choices

import itertools

from wtforms import widgets
from wtforms.fields.core import Field
from wtforms.validators import ValidationError

__all__ = (

class SelectFieldBase(Field):
    option_widget = widgets.Option()

    Base class for fields which can be iterated to produce options.

    This isn't a field, but an abstract base class for fields which want to
    provide this functionality.

    def __init__(self, label=None, validators=None, option_widget=None, **kwargs):
        super().__init__(label, validators, **kwargs)

        if option_widget is not None:
            self.option_widget = option_widget

    def iter_choices(self):
        Provides data for choice widget rendering. Must return a sequence or
        iterable of (value, label, selected) tuples.
        raise NotImplementedError()

    def has_groups(self):
        return False

    def iter_groups(self):
        raise NotImplementedError()

    def __iter__(self):
        opts = dict(
        for i, (value, label, checked) in enumerate(self.iter_choices()):
            opt = self._Option(label=label, id="%s-%d" % (, i), **opts)
            opt.process(None, value)
            opt.checked = checked
            yield opt

    class _Option(Field):
        checked = False

        def _value(self):
            return str(

[docs]class SelectField(SelectFieldBase): widget = widgets.Select() def __init__( self, label=None, validators=None, coerce=str, choices=None, validate_choice=True, **kwargs, ): super().__init__(label, validators, **kwargs) self.coerce = coerce if callable(choices): choices = choices() if choices is not None: self.choices = choices if isinstance(choices, dict) else list(choices) else: self.choices = None self.validate_choice = validate_choice def iter_choices(self): if not self.choices: choices = [] elif isinstance(self.choices, dict): choices = list(itertools.chain.from_iterable(self.choices.values())) else: choices = self.choices return self._choices_generator(choices) def has_groups(self): return isinstance(self.choices, dict) def iter_groups(self): if isinstance(self.choices, dict): for label, choices in self.choices.items(): yield (label, self._choices_generator(choices)) def _choices_generator(self, choices): if not choices: _choices = [] elif isinstance(choices[0], (list, tuple)): _choices = choices else: _choices = zip(choices, choices) for value, label in _choices: yield (value, label, self.coerce(value) == def process_data(self, value): try: # If value is None, don't coerce to a value = self.coerce(value) if value is not None else None except (ValueError, TypeError): = None def process_formdata(self, valuelist): if not valuelist: return try: = self.coerce(valuelist[0]) except ValueError as exc: raise ValueError(self.gettext("Invalid Choice: could not coerce.")) from exc def pre_validate(self, form): if self.choices is None: raise TypeError(self.gettext("Choices cannot be None.")) if not self.validate_choice: return for _, _, match in self.iter_choices(): if match: break else: raise ValidationError(self.gettext("Not a valid choice."))
[docs]class SelectMultipleField(SelectField): """ No different from a normal select field, except this one can take (and validate) multiple choices. You'll need to specify the HTML `size` attribute to the select field when rendering. """ widget = widgets.Select(multiple=True) def _choices_generator(self, choices): if choices: if isinstance(choices[0], (list, tuple)): _choices = choices else: _choices = zip(choices, choices) else: _choices = [] for value, label in _choices: selected = is not None and self.coerce(value) in yield (value, label, selected) def process_data(self, value): try: = list(self.coerce(v) for v in value) except (ValueError, TypeError): = None def process_formdata(self, valuelist): try: = list(self.coerce(x) for x in valuelist) except ValueError as exc: raise ValueError( self.gettext( "Invalid choice(s): one or more data inputs could not be coerced." ) ) from exc def pre_validate(self, form): if self.choices is None: raise TypeError(self.gettext("Choices cannot be None.")) if not self.validate_choice or not return acceptable = {c[0] for c in self.iter_choices()} if any(d not in acceptable for d in unacceptable = [str(d) for d in set( - acceptable] raise ValidationError( self.ngettext( "'%(value)s' is not a valid choice for this field.", "'%(value)s' are not valid choices for this field.", len(unacceptable), ) % dict(value="', '".join(unacceptable)) )
[docs]class RadioField(SelectField): """ Like a SelectField, except displays a list of radio buttons. Iterating the field will produce subfields (each containing a label as well) in order to allow custom rendering of the individual radio fields. """ widget = widgets.ListWidget(prefix_label=False) option_widget = widgets.RadioInput()