实现表单中多对多字段的单选（Django）

古城微笑少年丶 2022-03-21 04:38 198阅读 0赞

在工作发现多对多字段在前台表单中显示为单选框，但是不能成功保存，

找了很多资料也没有，就将Django中自带的Checkboxinput类（复选框，能成功保存）

自定义为Radioinput，并自定义RadioSelectForM2M的Widget来实现多对多字段显示

为单选框形式，并能成功保存，代码如下

\#-\*- coding:utf-8 -\*-

from django.forms.widgets import Widget, force\_unicode, mark\_safe, \\  
flatatt, SelectMultiple, chain, conditional\_escape  
  
'''  
    将django中的CheckboxInput类拷过来，改成自己的RadioInput和RadioSelectForM2M，  
    因为RadioSelect作为manytomanyfield的widget保存时会出错。  
'''  
class RadioInput(Widget):  
    def \_\_init\_\_(self, attrs=None, check\_test=bool):  
        super(RadioInput, self).\_\_init\_\_(attrs)  
        \# check\_test is a callable that takes a value and returns True  
        \# if the checkbox should be checked for that value.  
        self.check\_test = check\_test  
  
    def render(self, name, value, attrs=None):  
        final\_attrs = self.build\_attrs(attrs, type='radio', name=name)  
        try:  
            result = self.check\_test(value)  
        except: \# Silently catch exceptions  
            result = False  
        if result:  
            final\_attrs\['checked'\] = 'checked'  
        if value not in ('', True, False, None):  
            \# Only add the 'value' attribute if a value is non-empty.  
            final\_attrs\['value'\] = force\_unicode(value)  
        return mark\_safe(u'<input%s />' % flatatt(final\_attrs))  
  
    def value\_from\_datadict(self, data, files, name):  
        if name not in data:  
            \# A missing value means False because HTML form submission does not  
            \# send results for unselected checkboxes.  
            return False  
        value = data.get(name)  
        \# Translate true and false strings to boolean values.  
        values = \{'true': True, 'false': False\}  
        if isinstance(value, basestring):  
            value = values.get(value.lower(), value)  
        return value  
  
    def \_has\_changed(self, initial, data):  
        \# Sometimes data or initial could be None or u'' which should be the  
        \# same thing as False.  
        return bool(initial) != bool(data)  
  
  
class RadioSelectForM2M(SelectMultiple):  
    def render(self, name, value, attrs=None, choices=()):  
        if value is None: value = \[\]  
        has\_id = attrs and 'id' in attrs  
        final\_attrs = self.build\_attrs(attrs, name=name)  
        output = \[u'<ul>'\]  
        \# Normalize to strings  
        str\_values = set(\[force\_unicode(v) for v in value\])  
        for i, (option\_value, option\_label) in enumerate(chain(self.choices, choices)):  
            \# If an ID attribute was given, add a numeric index as a suffix,  
            \# so that the checkboxes don't all have the same ID attribute.  
            if has\_id:  
                final\_attrs = dict(final\_attrs, id='%s\_%s' % (attrs\['id'\], i))  
                label\_for = u' for="%s"' % final\_attrs\['id'\]  
            else:  
                label\_for = ''  
  
            rb = RadioInput(final\_attrs, check\_test=lambda value: value in str\_values)  
            option\_value = force\_unicode(option\_value)  
            rendered\_cb = rb.render(name, option\_value)  
            option\_label = conditional\_escape(force\_unicode(option\_label))  
            output.append(u'<li><label%s>%s %s</label></li>' % (label\_for, rendered\_cb, option\_label))  
        output.append(u'</ul>')  
        return mark\_safe(u'\\n'.join(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)