如何使Python函数返回静态变量？

我正在尝试构建一个用于检查重复图像哈希的方法。为此，我在表单验证程序中使用了一个嵌套函数。问题是，当我在外部函数中设置一个变量（内部函数的结果）时，对外部变量的任何后续引用都会再次调用内部函数

例如：

def dupe_check(self, field):
    def get_hash():
        f = field.data
        img = Image.open(f)
        imghash = imagehash.dhash(img)
        f.seek(0)
        return imghash
    imghash = get_hash()
    hashcheck = Sights.query.filter(Sights.image_hash == imghash).first()
    if hashcheck == imghash:
        print('dupe')
        raise ValidationError('duplicate hash!')
    else:
        print('no dupe') 

如果运行时数据库中没有散列，我会打印

无重复

，然后上传图像

但是，如果哈希存在于数据库中，当执行到达

时，如果hashcheck==imghash:

我会崩溃，因为

imghash

似乎再次调用

get\u hash（）

，而不是简单地返回先前使用

imghash=get\u hash（）

设置的哈希字符串

您可以在下面看到，

imagehash

程序被调用（并崩溃），而不仅仅是哈希字符串

127.0.0.1 - - [17/Sep/2017 17:49:36] "POST /add HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/app.py", line 1997, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/app.py", line 1985, in wsgi_app
    response = self.handle_exception(e)
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/app.py", line 1540, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/app.py", line 1982, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/app.py", line 1614, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/app.py", line 1517, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask/app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/mrrg/dev/flaskimg/project/sights/views.py", line 74, in add_image
    if form.validate_on_submit():
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/flask_wtf/form.py", line 101, in validate_on_submit
    return self.is_submitted() and self.validate()
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/wtforms/form.py", line 310, in validate
    return super(Form, self).validate(extra)
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/wtforms/form.py", line 152, in validate
    if not field.validate(self, extra):
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/wtforms/fields/core.py", line 204, in validate
    stop_validation = self._run_validation_chain(form, chain)
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/wtforms/fields/core.py", line 224, in _run_validation_chain
    validator(form, self)
  File "/home/mrrg/dev/flaskimg/project/sights/forms.py", line 71, in dupe_check
    if hashcheck == imghash:
  File "/home/mrrg/dev/flaskimg/venv/lib/python3.5/site-packages/imagehash/__init__.py", line 85, in __eq__
    return numpy.array_equal(self.hash.flatten(), other.hash.flatten())
AttributeError: 'Sights' object has no attribute 'hash'

我想

imghash=get_hash（）

会设置从内部函数返回的变量的新实例吗？如何设置一个静态变量来进行操作，并避免对内部函数的额外调用

---

我还尝试在内部函数的

imghash

上设置全局/非局部，结果相同。

据我所知，您的代码尝试将一个Sight对象与ImageHash对象进行比较，但Sight类代码实现仅在两个Sight对象之间进行比较，因此出现错误

，我不确定是否理解您的意思。我不是在一个视界内比较。我定义了两个变量：

imghash

是从内部函数创建的，

hashcheck

是从SQLAlchemy查询创建的。您能告诉我变量hashcheck和imghash的类型吗？啊，我知道了，我有两种不同的变量类型：

和

。规范化变量以进行比较的最佳方法是什么？对于散列值，我认为将对象类型强制转换为字符串以进行比较是合适的，这最终会起作用。谢谢您的帮助@Tung-vs。