flask-admin：当前用户在从flask admin中的ModelView继承的类中使用时返回none

Question

当我通过在我自己的类名 UserDeleteView 中从 flask_admin.contrib.sqla 继承 ModelView 类来制作我自己的模型视图时，我有一个关于 flask_admin 的错误，当我在 UserDeleteView 中使用 current_user（flask_login 的变量）时它给出 None 但是当我在 UserDeleteView 的任何功能中使用它时，它都能正常工作

就像我在 UserDeleteView 类的 is_accessable 函数中使用它一样，但是当我在 UserDeleteView 类的 if 中使用它时它不起作用

这是我的 flask_admin 代码：-

class UserDeleteView(ModelView):

    def is_accessible(self):
        return "User" in {i.split()[0] for i in current_user.permissions() }

    if "User w" not in current_user.permissions():
        can_delete=False


class PostVarificationView(BaseView):
    @expose("/")
    def index(self):
        return self.render('admin/post_varification.html')

class MyAdminIndexView(AdminIndexView):
    def is_accessible(self):
        return (current_user.is_authenticated and len(current_user.permissions())!=0)

admin = Admin(app,index_view=MyAdminIndexView(),name="Microblog")
admin.add_view(UserDeleteView( User, db.session ))
admin.add_view(PostVarificationView(name="Post Varification",endpoint="PostVarification"))

这是我得到的错误：

AttributeError: 'NoneType' object has no attribute 'permissions'

Traceback (most recent call last)
File "/home/chirag/Documents/Projects/microblog1/microblog.py", line 1, in <module>
from app import app,db
File "/home/chirag/Documents/Projects/microblog1/app/__init__.py", line 21, in <module>
from app import routes, models, errors
File "/home/chirag/Documents/Projects/microblog1/app/routes.py", line 309, in <module>
class UserDeleteView(ModelView):
File "/home/chirag/Documents/Projects/microblog1/app/routes.py", line 314, in UserDeleteView
if "User w" not in current_user.permissions():
File "/home/chirag/Documents/Project venv/microblog1/lib/python3.7/site-packages/werkzeug/local.py", line 348, in __getattr__
return getattr(self._get_current_object(), name)
AttributeError: 'NoneType' object has no attribute 'permissions'

Answer 1

类主体中定义的代码在第一次导入模块时执行，没有current_user 因此出现错误。请参阅此 SO 问题"Why does a class' body get executed at definition time?" 以进一步阅读。

用方法替换can_delete，用@property装饰，current_user就可以使用了。

示例：

class UserDeleteView(ModelView):

    def is_accessible(self):
        return "User" in {i.split()[0] for i in current_user.permissions() }

    @property
    def can_delete(self):
        # Your logic here
        return "User w" in current_user.permissions()