使用Django Forms API控制选择输入的级别

Question

我想在使用Django表单API的下拉选择框中，给选项元素添加一个label属性，但又不想覆盖下拉框的render_options方法。请问这样做可能吗？如果可以，应该怎么做呢？

注意：我想直接给选项添加label属性（这在XHTML严格标准中是有效的），而不是给选项组添加。

Answer 1

我怕这是不可能的，除非你对Select这个小部件进行子类化，也就是自己重新定义它的显示方式，正如你所猜的那样。Select的代码并没有为每个<option>项提供任何属性。它只包含选项的值、是否被选中的状态和标签……就这些了，我很抱歉：

def render_option(option_value, option_label):
    option_value = force_unicode(option_value)
    selected_html = (option_value in selected_choices) and u' selected="selected"' or ''
    return u'<option value="%s"%s>%s</option>' % (
        escape(option_value), selected_html,
        conditional_escape(force_unicode(option_label)))

Answer 2

我刚写了一个类来实现这个功能：

from django.forms.widgets import Select
from django.utils.encoding import force_unicode
from itertools import chain
from django.utils.html import escape, conditional_escape


class ExtendedSelect(Select):
    """
    A subclass of Select that adds the possibility to define additional 
    properties on options.

    It works as Select, except that the ``choices`` parameter takes a list of
    3 elements tuples containing ``(value, label, attrs)``, where ``attrs``
    is a dict containing the additional attributes of the option.
    """

    def render_options(self, choices, selected_choices):
        def render_option(option_value, option_label, attrs):
            option_value = force_unicode(option_value)
            selected_html = (option_value in selected_choices) and u' selected="selected"' or ''
            attrs_html = []
            for k, v in attrs.items():
                attrs_html.append('%s="%s"' % (k, escape(v)))
            if attrs_html:
                attrs_html = " " + " ".join(attrs_html)
            else:
                attrs_html = ""
            return u'<option value="%s"%s%s>%s</option>' % (
                escape(option_value), selected_html, attrs_html,
                conditional_escape(force_unicode(option_label)))
        # Normalize to strings.
        selected_choices = set([force_unicode(v) for v in selected_choices])
        output = []
        for option_value, option_label, option_attrs in chain(self.choices, choices):
            if isinstance(option_label, (list, tuple)):
                output.append(u'<optgroup label="%s">' % escape(force_unicode(option_value)))
                for option in option_label:
                    output.append(render_option(*option))
                output.append(u'</optgroup>')
            else:
                output.append(render_option(option_value, option_label,
                    option_attrs))
        return u'\n'.join(output)

举个例子：

select = ExtendedSelect(choices=(
        (1, "option 1", {"label": "label 1"}),
        (2, "option 2", {"label": "label 2"}),
    ))