import re
from django.core.exceptions import ValidationError
from django.forms.utils import RenderableFieldMixin, pretty_name
from django.forms.widgets import MultiWidget, Textarea, TextInput
from django.utils.functional import cached_property
from django.utils.html import format_html, html_safe
from django.utils.translation import gettext_lazy as _
__all__ = ("BoundField",)
[docs]
class BoundField(RenderableFieldMixin):
"A Field plus data"
def __init__(self, form, field, name):
self.form = form
self.field = field
self.name = name
self.html_name = form.add_prefix(name)
self.html_initial_name = form.add_initial_prefix(name)
self.html_initial_id = form.add_initial_prefix(self.auto_id)
if self.field.label is None:
self.label = pretty_name(name)
else:
self.label = self.field.label
self.help_text = field.help_text or ""
self.renderer = form.renderer
@cached_property
def subwidgets(self):
"""
Most widgets yield a single subwidget, but others like RadioSelect and
CheckboxSelectMultiple produce one subwidget for each choice.
This property is cached so that only one database query occurs when
rendering ModelChoiceFields.
"""
id_ = self.field.widget.attrs.get("id") or self.auto_id
attrs = {"id": id_} if id_ else {}
attrs = self.build_widget_attrs(attrs)
return [
BoundWidget(self.field.widget, widget, self.form.renderer)
for widget in self.field.widget.subwidgets(
self.html_name, self.value(), attrs=attrs
)
]
def __bool__(self):
# BoundField evaluates to True even if it doesn't have subwidgets.
return True
def __iter__(self):
return iter(self.subwidgets)
def __len__(self):
return len(self.subwidgets)
def __getitem__(self, idx):
# Prevent unnecessary reevaluation when accessing BoundField's attrs
# from templates.
if not isinstance(idx, (int, slice)):
raise TypeError(
"BoundField indices must be integers or slices, not %s."
% type(idx).__name__
)
return self.subwidgets[idx]
@property
def errors(self):
"""
Return an ErrorList (empty if there are no errors) for this field.
"""
return self.form.errors.get(
self.name, self.form.error_class(renderer=self.form.renderer)
)
@property
def template_name(self):
return self.field.template_name or self.form.renderer.field_template_name
[docs]
def as_widget(self, widget=None, attrs=None, only_initial=False):
"""
Render the field by rendering the passed widget, adding any HTML
attributes passed as attrs. If a widget isn't specified, use the
field's default widget.
"""
widget = widget or self.field.widget
if self.field.localize:
widget.is_localized = True
attrs = attrs or {}
attrs = self.build_widget_attrs(attrs, widget)
if self.auto_id and "id" not in widget.attrs:
attrs.setdefault(
"id", self.html_initial_id if only_initial else self.auto_id
)
if only_initial and self.html_initial_name in self.form.data:
# Propagate the hidden initial value.
value = self.form._widget_data_value(
self.field.hidden_widget(),
self.html_initial_name,
)
else:
value = self.value()
return widget.render(
name=self.html_initial_name if only_initial else self.html_name,
value=value,
attrs=attrs,
renderer=self.form.renderer,
)
def as_text(self, attrs=None, **kwargs):
"""
Return a string of HTML for representing this as an <input type="text">.
"""
return self.as_widget(TextInput(), attrs, **kwargs)
def as_textarea(self, attrs=None, **kwargs):
"""Return a string of HTML for representing this as a <textarea>."""
return self.as_widget(Textarea(), attrs, **kwargs)
@property
def data(self):
"""
Return the data for this BoundField, or None if it wasn't given.
"""
return self.form._widget_data_value(self.field.widget, self.html_name)
[docs]
def value(self):
"""
Return the value for this BoundField, using the initial value if
the form is not bound or the data otherwise.
"""
data = self.initial
if self.form.is_bound:
data = self.field.bound_data(self.data, data)
return self.field.prepare_value(data)
def _has_changed(self):
field = self.field
if field.show_hidden_initial:
hidden_widget = field.hidden_widget()
initial_value = self.form._widget_data_value(
hidden_widget,
self.html_initial_name,
)
try:
initial_value = field.to_python(initial_value)
except ValidationError:
# Always assume data has changed if validation fails.
return True
else:
initial_value = self.initial
return field.has_changed(initial_value, self.data)
[docs]
def label_tag(self, contents=None, attrs=None, label_suffix=None, tag=None):
"""
Wrap the given contents in a <label>, if the field has an ID attribute.
contents should be mark_safe'd to avoid HTML escaping. If contents
aren't given, use the field's HTML-escaped label.
If attrs are given, use them as HTML attributes on the <label> tag.
label_suffix overrides the form's label_suffix.
"""
contents = contents or self.label
if label_suffix is None:
label_suffix = (
self.field.label_suffix
if self.field.label_suffix is not None
else self.form.label_suffix
)
# Only add the suffix if the label does not end in punctuation.
# Translators: If found as last label character, these punctuation
# characters will prevent the default label_suffix to be appended to the label
if label_suffix and contents and contents[-1] not in _(":?.!"):
contents = format_html("{}{}", contents, label_suffix)
widget = self.field.widget
id_ = widget.attrs.get("id") or self.auto_id
if id_:
id_for_label = widget.id_for_label(id_)
if id_for_label:
attrs = {**(attrs or {}), "for": id_for_label}
if self.field.required and hasattr(self.form, "required_css_class"):
attrs = attrs or {}
if "class" in attrs:
attrs["class"] += " " + self.form.required_css_class
else:
attrs["class"] = self.form.required_css_class
context = {
"field": self,
"label": contents,
"attrs": attrs,
"use_tag": bool(id_),
"tag": tag or "label",
}
return self.form.render(self.form.template_name_label, context)
[docs]
def legend_tag(self, contents=None, attrs=None, label_suffix=None):
"""
Wrap the given contents in a <legend>, if the field has an ID
attribute. Contents should be mark_safe'd to avoid HTML escaping. If
contents aren't given, use the field's HTML-escaped label.
If attrs are given, use them as HTML attributes on the <legend> tag.
label_suffix overrides the form's label_suffix.
"""
return self.label_tag(contents, attrs, label_suffix, tag="legend")
[docs]
def css_classes(self, extra_classes=None):
"""
Return a string of space-separated CSS classes for this field.
"""
if hasattr(extra_classes, "split"):
extra_classes = extra_classes.split()
extra_classes = set(extra_classes or [])
if self.errors and hasattr(self.form, "error_css_class"):
extra_classes.add(self.form.error_css_class)
if self.field.required and hasattr(self.form, "required_css_class"):
extra_classes.add(self.form.required_css_class)
return " ".join(extra_classes)
@property
def is_hidden(self):
"""Return True if this BoundField's widget is hidden."""
return self.field.widget.is_hidden
@property
def auto_id(self):
"""
Calculate and return the ID attribute for this BoundField, if the
associated Form has specified auto_id. Return an empty string otherwise.
"""
auto_id = self.form.auto_id # Boolean or string
if auto_id and "%s" in str(auto_id):
return auto_id % self.html_name
elif auto_id:
return self.html_name
return ""
@property
def id_for_label(self):
"""
Wrapper around the field widget's `id_for_label` method.
Useful, for example, for focusing on this field regardless of whether
it has a single widget or a MultiWidget.
"""
widget = self.field.widget
id_ = widget.attrs.get("id") or self.auto_id
return widget.id_for_label(id_)
@cached_property
def initial(self):
return self.form.get_initial_for_field(self.field, self.name)
def build_widget_attrs(self, attrs, widget=None):
widget = widget or self.field.widget
attrs = dict(attrs) # Copy attrs to avoid modifying the argument.
if (
widget.use_required_attribute(self.initial)
and self.field.required
and self.form.use_required_attribute
):
# MultiValueField has require_all_fields: if False, fall back
# on subfields.
if (
hasattr(self.field, "require_all_fields")
and not self.field.require_all_fields
and isinstance(self.field.widget, MultiWidget)
):
for subfield, subwidget in zip(self.field.fields, widget.widgets):
subwidget.attrs["required"] = (
subwidget.use_required_attribute(self.initial)
and subfield.required
)
else:
attrs["required"] = True
if self.field.disabled:
attrs["disabled"] = True
if not widget.is_hidden and self.errors:
attrs["aria-invalid"] = "true"
# If a custom aria-describedby attribute is given (either via the attrs
# argument or widget.attrs) and help_text is used, the custom
# aria-described by is preserved so user can set the desired order.
if (
not attrs.get("aria-describedby")
and not widget.attrs.get("aria-describedby")
and self.field.help_text
and not self.use_fieldset
and self.auto_id
):
attrs["aria-describedby"] = f"{self.auto_id}_helptext"
return attrs
@property
def widget_type(self):
return re.sub(
r"widget$|input$", "", self.field.widget.__class__.__name__.lower()
)
@property
def use_fieldset(self):
"""
Return the value of this BoundField widget's use_fieldset attribute.
"""
return self.field.widget.use_fieldset
@html_safe
class BoundWidget:
"""
A container class used for iterating over widgets. This is useful for
widgets that have choices. For example, the following can be used in a
template:
{% for radio in myform.beatles %}
<label for="{{ radio.id_for_label }}">
{{ radio.choice_label }}
<span class="radio">{{ radio.tag }}</span>
</label>
{% endfor %}
"""
def __init__(self, parent_widget, data, renderer):
self.parent_widget = parent_widget
self.data = data
self.renderer = renderer
def __str__(self):
return self.tag(wrap_label=True)
def tag(self, wrap_label=False):
context = {"widget": {**self.data, "wrap_label": wrap_label}}
return self.parent_widget._render(self.template_name, context, self.renderer)
@property
def template_name(self):
if "template_name" in self.data:
return self.data["template_name"]
return self.parent_widget.template_name
@property
def id_for_label(self):
return self.data["attrs"].get("id")
@property
def choice_label(self):
return self.data["label"]
Jan 15, 2024