Django-models:选项，选择，小部件如何更改小部件的默认选项

Question

我对模型有问题，例如我有

fallBack = models.CharField(max_length=100, choices=FALLBACK,  default = 99,blank = True,null = True)
FALLBACK = (
    (u'99','-'),
    (u'standard', u'Standard TPF deactivation/exlusion applies'),
    (u'fallback', u'Fallback script provided'),
    (u'na',u'N/A'),
    (u'other',u'Other'),
    )

如果我将在模板中使用

{% for obj in form.forms %}
    {{obj.fallBack}}
{% endfor %}

它会像这样返回一些东西

<select name="form-0-fallBack" id="id_form-0-fallBack">
    <option value="">---------</option>
    <option value="99" selected="selected">-</option>
    <option value="standard">Standard TPF deactivation/exlusion applies</option>
    <option value="fallback">Fallback script provided</option>
    <option value="na">N/A</option>
    <option value="other">Other</option>
</select>

但我想做这样的东西：

<select **onchange="javascript:make()"** name="form-0-fallBack" id="id_form-0-fallBack">
    <option value="">---------</option>
    <option value="99" selected="selected">-</option>
    <option value="standard">Standard TPF deactivation/exlusion applies</option>
    <option value="fallback">Fallback script provided</option>
    <option value="na">N/A</option>
    <option value="other">Other</option>
</select>

如何做到这一点？我可以在模板中写这个第二个选项，而不是{{obj.fallBack}}，但是我的formset.is_valid()不起作用，什么时候我会这样做：

1)I will choose from fallBack second option(Standard TPF deactivation/exlusion applies) 
2) submit,
3) I have some error in other place in template 
4) Then my obj.fallBack returning to default option (99 , -) 

感谢你的帮助

Answer 1

好的，用这个属性创建新的Field而不是charfield

widget=forms.Select(attrs={'onchange': 'javascript:make()'})

感谢你的帮助

Answer 2

查看Widgets上的django文档

widget=forms.Select(attrs={'onchange': 'javascript:make()'})

这看起来像一个ModelForm，看看如何为ModelForms指定小部件