Question

我正在尝试创建一个自定义Django ModelForm元类，该类将允许对从源模型继承的Form字段进行一些额外的自定义，例如：

将选择限制为特定模型字段可用的全部子集
定义只读和必填字段
设置字段的初始值

之所以这样做，是因为我需要几个不同的ModelForms用于单个Model，每个都有上述选项的变体。这是我的元类：

class CustomModelFormMetaclass(models.ModelFormMetaclass):
"""
Custom ModelForm metaclass which adds extra configuration of fields inherited from Model
"""
def __new__(mcs, name, bases, attrs):
    new_class = super(models.ModelFormMetaclass, mcs).__new__(mcs, name, bases, attrs)
    # Set initial field values
    #initials = attrs.get('initial_values')
    for field_name, initial_value in new_class.initial_values.items():
        field = new_class.base_fields.get(field_name, None)
        if field and field.initial is None:
            field.initial = initial_value

    # Set refined choices
    #refined_choices = attrs.get('refined_choices')
    for field_name, refined_choices in new_class.refined_choices.items():
        set_field_choices(new_class, field_name,refined_choices)

    # Set disabled fields
    for field_name in new_class.read_only_fields:
        field = new_class.base_fields.get(field_name, None)
        if field:
            #field.disabled=True
            field.widget.attrs['readonly'] = True

    # Set required fields
    for field_name in new_class.required_fields:
        field = new_class.base_fields.get(field_name, None)
        if field:
            field.required=True

    # Set DateTime and Date help texts
    for field in new_class.base_fields.values():
        if field.help_text is None:
            if type(field).__name__ == 'DateTimeField':
                field.help_text = 'YYYY-MM-DD HH:MM:SS'
            elif type(field).__name__ == 'DateField':
                field.help_text = 'YYYY-MM-DD'

    return new_class

以及将作为实际ModelForms父类的基本自定义ModelForm类：

class CustomModelForm(forms.BaseModelForm, metaclass=CustomModelFormMetaclass):
method='post'
target=None
target_params={}

refined_choices={}

initial_values={}

read_only_fields=[]

required_fields= []

一个这样的例子是（这种情况没有利用我的自定义参数）：

class LBSListAdminForm(darwin_forms.CustomModelForm):
method = 'get'

class Meta:
    model = LBSListRequest
    exclude = ['start_time', 'site', 'process_id', 'user', 'duration', 'method', 'request_data', 'status', 'response']
    labels = {}
    help_texts = {}
    error_messages = {}
    widgets = {}

但是我遇到此错误：

“ LBSListAdminForm”对象没有属性“ _meta”

我在这里做错了什么？具有多个继承级别的metclass链变得令人困惑。感谢任何帮助

欢呼

Answer 1

_meta属性由ModelFormMetaclass中的__new__设置。问题是您没有在子类中正确调用super()，因此__new__中没有调用ModelFormMetaclass，因此未设置_meta。 / p>

对super()的调用应将当前类作为其第一个参数，因此应读为：

new_class = super(models.CustomModelFormMetaclass, mcs).__new__(mcs, name, bases, attrs)

Django自定义ModelForm元类，“对象没有属性'_meta'”

1 个答案: