117 lines
4.1 KiB
Python
117 lines
4.1 KiB
Python
from __future__ import annotations
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from typing import Any
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from collections.abc import Mapping
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from django.core.files.uploadedfile import UploadedFile
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from django.forms.renderers import BaseRenderer
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from django.forms.widgets import CheckboxInput, Media, Widget
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from django.utils.datastructures import MultiValueDict
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from django.utils.html import conditional_escape
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from django.utils.safestring import SafeString, mark_safe
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from django.utils.translation import gettext_lazy as _
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class ClearableWidgetWrapper(Widget):
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"""
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Wraps another widget adding a clear checkbox, making it possible to
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reset the field to some empty value even if the original input doesn't
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have means to.
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Useful for ``TextInput`` and ``Textarea`` based widgets used in combination
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with nullable text fields.
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Use it in ``Field.formfield`` or ``ModelAdmin.formfield_for_dbfield``:
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field.widget = ClearableWidgetWrapper(field.widget)
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``None`` is assumed to be a proper choice for the empty value, but you may
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pass another one to the constructor.
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"""
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clear_checkbox_label = _("None")
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template = '<span class="clearable-input">{0} <span>{2}</span> {3}</span>'
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# TODO: Label would be proper, but admin applies some hardly undoable
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# styling to labels.
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# template = '<span class="clearable-input">{} <label for="{}">{}</label> {}</span>'
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class Media:
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js = ("modeltranslation/js/clearable_inputs.js",)
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def __init__(self, widget: Widget, empty_value: Any | None = None) -> None:
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"""
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Remebers the widget we are wrapping and precreates a checkbox input.
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Allows overriding the empty value.
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"""
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self.widget = widget
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self.checkbox = CheckboxInput(attrs={"tabindex": "-1"})
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self.empty_value = empty_value
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def __getattr__(self, name: str) -> Any:
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"""
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If we don't have a property or a method, chances are the wrapped
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widget does.
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"""
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if name != "widget":
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return getattr(self.widget, name)
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raise AttributeError
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@property
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def media(self):
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"""
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Combines media of both components and adds a small script that unchecks
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the clear box, when a value in any wrapped input is modified.
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"""
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return self.widget.media + self.checkbox.media + Media(self.Media)
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def render(
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self,
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name: str,
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value: Any,
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attrs: dict[str, Any] | None = None,
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renderer: BaseRenderer | None = None,
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) -> SafeString:
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"""
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Appends a checkbox for clearing the value (that is, setting the field
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with the ``empty_value``).
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"""
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wrapped = self.widget.render(name, value, attrs, renderer)
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checkbox_name = self.clear_checkbox_name(name)
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checkbox_id = self.clear_checkbox_id(checkbox_name)
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checkbox_label = self.clear_checkbox_label
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checkbox = self.checkbox.render(
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checkbox_name, value == self.empty_value, attrs={"id": checkbox_id}, renderer=renderer
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)
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return mark_safe(
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self.template.format(
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conditional_escape(wrapped),
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conditional_escape(checkbox_id),
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conditional_escape(checkbox_label),
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conditional_escape(checkbox),
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)
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)
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def value_from_datadict(
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self, data: Mapping[str, Any], files: MultiValueDict[str, UploadedFile], name: str
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) -> Any:
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"""
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If the clear checkbox is checked returns the configured empty value,
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completely ignoring the original input.
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"""
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clear = self.checkbox.value_from_datadict(data, files, self.clear_checkbox_name(name))
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if clear:
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return self.empty_value
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return self.widget.value_from_datadict(data, files, name)
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def clear_checkbox_name(self, name: str) -> str:
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"""
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Given the name of the input, returns the name of the clear checkbox.
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"""
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return name + "-clear"
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def clear_checkbox_id(self, name: str) -> str:
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"""
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Given the name of the clear checkbox input, returns the HTML id for it.
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"""
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return name + "_id"
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