django - 两个字段中的小部件填充值

Question

我知道，如果我需要为 django-admin 中的字段自定义“选择器”，我需要创建一个自定义小部件。但是如果小部件必须产生两个值，例如 X 和 Y 坐标，我如何将它们填充到模型的两个不同字段中？

Answer 1

您可以查看日期时间字段的实现，该字段在管理员中呈现为 2 个字段。

自上而下，

管理员使用

class AdminSplitDateTime(forms.SplitDateTimeWidget):
    """
    A SplitDateTime Widget that has some admin-specific styling.
    """
    def __init__(self, attrs=None):
        widgets = [AdminDateWidget, AdminTimeWidget]
        # Note that we're calling MultiWidget, not SplitDateTimeWidget, because
        # we want to define widgets.
        forms.MultiWidget.__init__(self, widgets, attrs)

    def format_output(self, rendered_widgets):
        return mark_safe(u'<p class="datetime">%s %s<br />%s %s</p>' % \
            (_('Date:'), rendered_widgets[0], _('Time:'), rendered_widgets[1]))

反过来使用SplitDateTimeWidget：

class SplitDateTimeWidget(MultiWidget):
    """
    A Widget that splits datetime input into two <input type="text"> boxes.
    """
    date_format = DateInput.format
    time_format = TimeInput.format

    def __init__(self, attrs=None, date_format=None, time_format=None):
        if date_format:
            self.date_format = date_format
        if time_format:
            self.time_format = time_format
        widgets = (DateInput(attrs=attrs, format=self.date_format),
                   TimeInput(attrs=attrs, format=self.time_format))
        super(SplitDateTimeWidget, self).__init__(widgets, attrs)

    def decompress(self, value):
        if value:
            return [value.date(), value.time().replace(microsecond=0)]
        return [None, None]

这反过来又扩展了您还应该扩展的MultiWidget定义。django.forms.widgets它有许多可以覆盖的有用方法。

class MultiWidget(Widget):
"""
A widget that is composed of multiple widgets.

Its render() method is different than other widgets', because it has to
figure out how to split a single value for display in multiple widgets.
The ``value`` argument can be one of two things:

    * A list.
    * A normal value (e.g., a string) that has been "compressed" from
      a list of values.

In the second case -- i.e., if the value is NOT a list -- render() will
first "decompress" the value into a list before rendering it. It does so by
calling the decompress() method, which MultiWidget subclasses must
implement. This method takes a single "compressed" value and returns a
list.

When render() does its HTML rendering, each value in the list is rendered
with the corresponding widget -- the first value is rendered in the first
widget, the second value is rendered in the second widget, etc.

Subclasses may implement format_output(), which takes the list of rendered
widgets and returns a string of HTML that formats them any way you'd like.

You'll probably want to use this class with MultiValueField.
"""
def __init__(self, widgets, attrs=None):
    self.widgets = [isinstance(w, type) and w() or w for w in widgets]
    super(MultiWidget, self).__init__(attrs)

def render(self, name, value, attrs=None):
    # value is a list of values, each corresponding to a widget
    # in self.widgets.
    if not isinstance(value, list):
        value = self.decompress(value)
    output = []
    final_attrs = self.build_attrs(attrs)
    id_ = final_attrs.get('id', None)
    for i, widget in enumerate(self.widgets):
        try:
            widget_value = value[i]
        except IndexError:
            widget_value = None
        if id_:
            final_attrs = dict(final_attrs, id='%s_%s' % (id_, i))
        output.append(widget.render(name + '_%s' % i, widget_value, final_attrs))
    return mark_safe(self.format_output(output))

def id_for_label(self, id_):
    # See the comment for RadioSelect.id_for_label()
    if id_:
        id_ += '_0'
    return id_
id_for_label = classmethod(id_for_label)

def value_from_datadict(self, data, files, name):
    return [widget.value_from_datadict(data, files, name + '_%s' % i) for i, widget in enumerate(self.widgets)]

def _has_changed(self, initial, data):
    if initial is None:
        initial = [u'' for x in range(0, len(data))]
    else:
        if not isinstance(initial, list):
            initial = self.decompress(initial)
    for widget, initial, data in zip(self.widgets, initial, data):
        if widget._has_changed(initial, data):
            return True
    return False

def format_output(self, rendered_widgets):
    """
    Given a list of rendered widgets (as strings), returns a Unicode string
    representing the HTML for the whole lot.

    This hook allows you to format the HTML design of the widgets, if
    needed.
    """
    return u''.join(rendered_widgets)

def decompress(self, value):
    """
    Returns a list of decompressed values for the given compressed value.
    The given value can be assumed to be valid, but not necessarily
    non-empty.
    """
    raise NotImplementedError('Subclasses must implement this method.')

def _get_media(self):
    "Media for a multiwidget is the combination of all media of the subwidgets"
    media = Media()
    for w in self.widgets:
        media = media + w.media
    return media
media = property(_get_media)

def __deepcopy__(self, memo):
    obj = super(MultiWidget, self).__deepcopy__(memo)
    obj.widgets = copy.deepcopy(self.widgets)
    return obj

Answer 2

Jannis Leidel 很久以前就发布了一个小部件。django-coordinatesfield 据我所知，它从地图中获取坐标并将其传递给单个字段，并且一些 javascript 将其切割为 2 个字段的 2 个坐标。

结合自定义表单，它应该可以很好地工作

Answer 3

这是 ModelForm 的示例：http: //www.adamalton.co.uk/blog/displaying-django-genericforeignkey-as-single-form-field/

向表单添加一个额外的表单字段（用于您的单个小部件）并排除两个“真实”字段，然后覆盖 init 和 save 方法以执行使其工作的额外逻辑。

另外，同样的问题： 如何让一个小部件在 Django 中设置 2 个字段？

Answer 4

您可以使小部件呈现两个（隐藏的）html 输入，它们的名称与需要填充的模型字段相关，并通过 javascript 为它们分配必要的值！