如何修改 Django 中间件 __call__ 方法中的 response.content

Question

I'm trying to remove all blank lines in xml response by processing it in a middleware as suggested in this example: https://code.djangoproject.com/wiki/StripWhitespaceMiddleware
Now the problem is that in Django 2.1 that code is no more current since Dajngo 1.10 the way the Middleware works changed quite a bit.
Now I see that the response.content is of type bytes and so no straightforward editable with regex.
What is the correct way to do this in Django 1.10+?

Answer 1

As your said, response.content is a bytes so all arguments in the regex have to by of type byte , including the replacement string.

    def __init__(self):
        self.whitespace = re.compile(b'^\s*\n', re.MULTILINE)
        #self.whitespace_lead = re.compile(b'^\s+', re.MULTILINE)
        #self.whitespace_trail = re.compile(b'\s+$', re.MULTILINE)


    def process_response(self, request, response):
        if "text" in response['Content-Type']:
        #Use next line instead to avoid failure on cached / HTTP 304 NOT MODIFIED responses without Content-Type
        #if response.status_code == 200 and "text" in response['Content-Type']:
            if hasattr(self, 'whitespace_lead'):
                response.content = self.whitespace_lead.sub(b'', response.content)
            if hasattr(self, 'whitespace_trail'):
                response.content = self.whitespace_trail.sub(b'\n', response.content)
            if hasattr(self, 'whitespace'):
                response.content = self.whitespace.sub(b'', response.content)
            return response
        else:
            return response    

From the documentation :

Both patterns and strings to be searched can be Unicode strings (str) as well as 8-bit strings (bytes). However, Unicode strings and 8-bit strings cannot be mixed : that is, you cannot match a Unicode string with a byte pattern or vice-versa; similarly, when asking for a substitution, the replacement string must be of the same type as both the pattern and the search string.