Python：NoneType错误 - “强制为Unicode：需要字符串或缓冲区，找到NoneType”

Question

我正在使用Google App Engine并使用数据存储为用户创建包含实体用户名，密码哈希，电子邮件和加入日期。但是当我运行一个函数来注册一个用户时，散列密码的函数返回NoneType错误。

我试图寻找错误，但窗体发布的值，我能够从头获取它们。

这是一段代码，处理注册

def make_salt(): 
chars = string.ascii_uppercase + string.ascii_lowercase + string.ascii_digits 
return ''.join(random.choice(chars) for x in range(5)) 

def make_pw_h(name, pw, salt = None): 
    if salt: 
     salt = make_salt() 
return "%s,%s" % (salt, hashlib.sha256(name + pw + salt).hexdigest()) 

def check_pw_h(name, pw, h): 
    h = h.split(',')[1] 
    return h == make_pw_h(name, pw, h) 

class Users(db.Model): 
    username = db.StringProperty(required = True) 
    pw_hash = db.StringProperty(required = True) 
    emai = db.StringProperty() 
    user_since = db.DateTimeProperty(auto_now_add = True) 

@classmethod 
def by_id(cls, uid): 
    return Users.get_by_id(uid) 

@classmethod 
def by_name(cls, name): 
    user = Users.all().filter('name = ', name).get() 
    return user 

@classmethod 
def register(cls, name, pw, email = None): 
    pw_h = make_pw_h(name, pw) 
    return Users(username = name, 
       pw_hash = pw_h, 
       email = email) 

@classmethod 
def login(cls, name, pw): 
    u = cls.by_name(name) 
    if u and check_pw(pw): 
     return u   

def make_secure_val(s): 
    return '%s|%s' % (val, hmac.new(secret, val).hexdigest()) 

def check_secure_val(sec_val): 
    val = val.split('|')[0] 
    if sec_val == make_secure_val(val): 
     return val 

class BaseHandler(webapp2.RequestHandler): 

#this function uses the render_str funcion to display the html form in the browser 
def render(self, template, **kw): 
    self.response.out.write(render_str(template, **kw)) 

#this funcion is a simple function using the template engine to write out the required data with 
#any extra parameters 
def write(self, *a, **kw): 
    self.response.out.write(*a, **kw) 

def set_sec_coki(self, name, val): 
    sec_val = make_secure_val(val) 
    self.response.headers.add_cookie('Set-Cookie', "%s=%s; Path=/" % (name, sec_val)) 

def read_sec_coki(self, name): 
    coki_val = self.request.cookies.get(name) 
    return coki_val and check_secure_val(coki_val) 

def Initialize(self, *a, **kw): 
    webapp2.RequestHandler.Initialize(self, *a, **kw) 
    uid = self.read_sec_coki('user-id') 
    self.user = uid and Users.by_id(int(uid)) 


class Signup(BaseHandler): 
def get(self): 
    self.render("signup-form.html") 

def post(self): 
    have_error = False 
    self.username = self.request.get('username') 
    self.password = self.request.get('password') 
    self.verify = self.request.get('verify') 
    self.email = self.request.get('email') 

    params = dict(username = self.username, 
        email = self.email) 

    if not valid_username(self.username): 
     params['error_username'] = "That's not a valid username." 
     have_error = True 

    if not valid_password(self.password): 
     params['error_password'] = "That wasn't a valid password." 
     have_error = True 
    elif self.password != self.verify: 
     params['error_verify'] = "Your passwords didn't match." 
     have_error = True 

    if not valid_email(self.email): 
     params['error_email'] = "That's not a valid email." 
     have_error = True 

    if have_error: 
     self.render('signup-form.html', **params) 
    else: 
     u = Users.by_name(self.username) 
     if u: 
      msg = "User already exists" 
      self.render('signup-form.html', error_username = msg) 
     else: 
      sing_user = Users.register(self.username, self.password, self.email) 
      sing_user.put() 

      self.login(sing_user) 


      self.set_sec_coki('user-id', sing_user.key().id()) 

      self.redirect('/welcome') 


class WelcomePage(BaseHandler): 
def get(self): 
    coki_val = read_sec_coki('user-id') 
    u_id = coki_val.check_secure_val(coki_val) 
    part_usr = u_id.by_id(int(u_id)) 
    name = part_usr.username 
    self.render("welcome.html", username = name) 

这是当我尝试通过的形式注册一个新用户，我得到的错误堆栈

Traceback (most recent call last): 
File "/home/bigb/google_projects/google_appengine/lib/webapp2/webapp2.py", line 1536, in  __call__ 
rv = self.handle_exception(request, response, e) 
File "/home/bigb/google_projects/google_appengine/lib/webapp2/webapp2.py", line 1530, in __call__ 
rv = self.router.dispatch(request, response) 
File "/home/bigb/google_projects/google_appengine/lib/webapp2/webapp2.py", line 1278, in default_dispatcher 
return route.handler_adapter(request, response) 
File "/home/bigb/google_projects/google_appengine/lib/webapp2/webapp2.py", line 1102, in __call__ 
return handler.dispatch() 
File "/home/bigb/google_projects/google_appengine/lib/webapp2/webapp2.py", line 572, in dispatch 
return self.handle_exception(e, self.app.debug) 
File "/home/bigb/google_projects/google_appengine/lib/webapp2/webapp2.py", line 570, in dispatch 
return method(*args, **kwargs) 
File "/home/bigb/google_projects/my-ramblings/blog.py", line 197, in post 
sing_user = Users.register(self.username, self.password, self.email) 
File "/home/bigb/google_projects/my-ramblings/blog.py", line 55, in register 
pw_h = make_pw_h(name, pw) 
File "/home/bigb/google_projects/my-ramblings/blog.py", line 32, in make_pw_h 
return "%s,%s" % (salt, hashlib.sha256(name + pw + salt).hexdigest()) 
TypeError: coercing to Unicode: need string or buffer, NoneType found 

Answer 1

你只需要两个参数name和pw，即可拨打make_pw_h()。你离开salt到默认，None：

def make_pw_h(name, pw, salt = None): 
    if salt: 
     salt = make_salt() 
    return "%s,%s" % (salt, hashlib.sha256(name + pw + salt).hexdigest()) 

这意味着if salt:测试False和你最终传递到Nonehashlib.sha256。

也许你的意思是测试如果salt是不集：

def make_pw_h(name, pw, salt=None): 
    if salt is None: 
     salt = make_salt() 
    return "%s,%s" % (salt, hashlib.sha256(name + pw + salt).hexdigest())