如何在allauth模板中正确加载ChoiceField与ModelChoiceField选项？

基于allauth默认模板，我希望构建一个包含ChoiceField和ModelChoiceField的自定义注册表单，已做如下调整：

accounts/models.py #

class Country(models.Model):
    name = models.CharField(max_length=20, unique=True)

    def __str__(self):
        return self.name

class CustomUser(AbstractUser):

    SALUTATION = (
        ('m', _('Mr')),
        ('f', _('Mrs')),
    )

    salutation = models.CharField(
        max_length=1,
        choices=SALUTATION,
        blank=True,
        null=True
    )
    country = models.ForeignKey(
        Country,
        on_delete=models.PROTECT,
        verbose_name=_('Country'),
        blank=True,
        null=True
    )

accounts/forms.py #

class CustomSignupForm(forms.Form):
    salutation = forms.ChoiceField(widget=Select, choices=CustomUser.SALUTATION, initial=CustomUser.SALUTATION)
    country = forms.ModelChoiceField(queryset=Country.objects.all(), initial=Country.objects.all())

templates/allauth/elements/field.html #

{% load allauth %}
{% if attrs.type == "select" %}
    <select name="{{ attrs.name }}" id="{{ attrs.id }}" class="form-select mb-3">
        {% for option in attrs.value %}
            <option value="{% if option.0 %}{{ option.0 }}{% else %}{{ option.id }}{% endif %}">
                {% if option.1 %}
                    {{ option.1 }}
                {% else %}
                    {{ option }}
                {% endif %}
            </option>
        {% endfor %}
    </select>
{% elif attrs.type == "checkbox" or attrs.type == "radio" %}
...

目前发现只有在表单中传递initial参数时，选项才会被填充到attrs.value中，但按预期应该由choices或queryset参数提供。请问是否有其他方式可以从attrs对象中获取这些值？

allauth的模板渲染逻辑里，attrs对象不会直接携带choices或queryset数据，你可以通过以下方式解决：

1. 从字段实例直接获取选项
   模板中放弃从attrs取数据，改为通过field对象获取选项列表。修改field.html的select部分：

   {% load allauth %}
   {% if attrs.type == "select" %}
       <select name="{{ attrs.name }}" id="{{ attrs.id }}" class="form-select mb-3">
           {% for option_value, option_label in field.field.choices %}
               <option value="{{ option_value }}" {% if field.value == option_value %}selected{% endif %}>
                   {{ option_label }}
               </option>
           {% endfor %}
       </select>
   {% elif attrs.type == "checkbox" or attrs.type == "radio" %}
   ...
   

   • 对ChoiceField，field.field.choices直接返回你定义的选项元组；
   • 对ModelChoiceField，field.field.choices自动将模型实例转换为(instance.id, instance.__str__())的元组，无需手动处理id和显示文本。

2. 修正表单的initial参数
   你当前的initial设置存在错误：

   • salutation的initial应设为单个值（比如'm'），而非整个选项列表；
   • country的initial应设为单个Country实例或其id，而非所有查询集。修正后的表单代码：

   class CustomSignupForm(forms.Form):
       salutation = forms.ChoiceField(widget=Select, choices=CustomUser.SALUTATION, initial='m')
       country = forms.ModelChoiceField(queryset=Country.objects.all(), initial=Country.objects.first())
   

3. 规范继承allauth的SignupForm
   建议直接继承allauth.account.forms.SignupForm，自动关联用户模型，更符合allauth扩展规范：

   from allauth.account.forms import SignupForm
   
   class CustomSignupForm(SignupForm):
       salutation = forms.ChoiceField(widget=Select, choices=CustomUser.SALUTATION, initial='m')
       country = forms.ModelChoiceField(queryset=Country.objects.all(), initial=Country.objects.first())
   
       def save(self, request):
           user = super().save(request)
           user.salutation = self.cleaned_data['salutation']
           user.country = self.cleaned_data['country']
           user.save()
           return user
   

内容的提问来源于stack exchange，提问作者CodeResearcher