Django Python str（）参数2必须是str，而不是int

我有一个带有值的12x12字典，全部为0 .

matchfield = {}
    for i in range(12):
        for j in range(12):
            matchfield[str((i, j))] = 0

我想用下面的代码片段将一些值设置为1（它检查周围的字段是否空闲）：

length = 4
m = randint(1, 10-length)
n = randint(1, 10)
for x in range(m-1, m+length+1):
    for y in range(n-1, n+1):
        if not matchfield[str((x, y))]:
            for k in range(length):
                matchfield[str((m+k, n))] = 1

如果我在python控制台中测试它，所有工作和4个选定的值都设置为1，但在我的Django视图函数中，我在下一行得到了一个TypeError：

matchfield [str（（m k，n））] = 1

Environment:


Request Method: GET
Request URL: https://www.maik-kusmat.de/schiffeversenken/start/

Django Version: 1.11.5
Python Version: 3.5.3
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.sites',
 'django.contrib.flatpages',
 'accounts',
 'home',
 'contact',
 'kopfrechnen',
 'braces',
 'ckeditor',
 'ckeditor_uploader',
 'battleship',
 'hangman']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 'django.contrib.flatpages.middleware.FlatpageFallbackMiddleware']



Traceback:

File "/home/pi/Dev/mkenergy/lib/python3.5/site-packages/django/core/handlers/exception.py" in inner
  41.             response = get_response(request)

File "/home/pi/Dev/mkenergy/lib/python3.5/site-packages/django/core/handlers/base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "/home/pi/Dev/mkenergy/lib/python3.5/site-packages/django/core/handlers/base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/home/pi/Dev/mkenergy/lib/python3.5/site-packages/django/contrib/auth/decorators.py" in _wrapped_view
  23.                 return view_func(request, *args, **kwargs)

File "/home/pi/Dev/mkenergy/src/battleship/views.py" in battleship_start
  36.                                 matchfield[str((m+k, n))] = 1

Exception Type: TypeError at /schiffeversenken/start/
Exception Value: str() argument 2 must be str, not int

我错过了什么？我不明白这个错误