在 Django 中只渲染 MultiWidget 的一部分 [英] Render only one part of a MultiWidget in Django

问题描述

我有一个带有 MultiWidget 的 Django 表单字段，其中包含两个 TextInput.

I have a Django Form Field with a MultiWidget that consists of two TextInputs.

在模板中渲染表单时，有一个方便的符号

When rendering the form in a template there is the handy notation

{{ formname.fieldname }}

用于渲染单个字段.当我将它用于带有 MultiWidget 的字段时，它将显示两个 HTML 输入元素.是否对仅显示第一个 HTML 输入元素的符号稍作修改?({{ formname.fieldname.0 }} 不起作用.)

for rendering a single field. When I use it for the field with the MultiWidget, it will display both HTML input elements. Is there a slight modification of the notation that will display only the first HTML input element? ({{ formname.fieldname.0 }} does not work.)

推荐答案

我找到了解决这个问题的方法，需要两段代码.

I found a solution to this problem that needs two pieces of code.

第一

将MultiWidget转成字符串的render方法比较长.我们需要复制并粘贴它，并在最后一行稍作修改，使其返回一个数组.

The render method that turns the MultiWidget into a string is relatively long. We need to copy&paste it with a tiny modification in the last line to make it returing an array instead.

class OurMultiWidget(forms.MultiWidget):
    ...

    def render(self, name, value, attrs=None):
        """Copy and past from original render method"""
        if self.is_localized:
            for widget in self.widgets:
                widget.is_localized = self.is_localized
        # 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))
        # Original:
        # return mark_safe(self.format_output(output))
        # Only this line was written by myself:
        return [mark_safe(self.format_output(x)) for x in output]

第二

在模板中写入{{ formname.fieldname }} 会自动调用字段的unicode方法并将结果作为字符串处理.因为我们想要一个数组，所以我们需要绕过 unicode 方法并直接访问它将返回的内容.这就是方法 as_widget.因此，要调用 OurMultiWidget 的第一部分，我们需要在模板中使用以下代码:

Writing {{ formname.fieldname }} in the template will automatically call the field's unicode method and treat the result as a string. As we want an array instead, we need to circumvent the unicode method and access directly what it will return. And this is the method as_widget. Thus, to call the first part of OurMultiWidget, we will need this code in the template:

{{ formname.fieldname.as_widget.0 }}

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