I am writing middleware that, when it receives a request containing a header 'Foo', modifies its value, before passing the request on.
Django makes direct assignment illegal, so these do not work:
request.headers['Foo'] = 'bar'
request['Foo'] = 'bar'
I do have a working solution, but it's a bit hacky:
request.headers.__dict__['_store']['foo']=('Foo','bar')
Is there a cleaner way of doing it that I've missed?
The HTTP headers are contained in request.META which is just a dictionary that you can read and write. In META the header names are prefixed with HTTP_ and uppercase. So to access the header 'Foo' you'd do:
request.META['HTTP_FOO'] = 'bar'
The headers property (cached property in fact) is just a convenient way to access the HTTP headers without having to worry about the prefix and uppercasing, but it's read-only.
To reset a cached property, just remove it from the instance's __dict__ like so:
request.__dict__.pop('headers', None)
This will make sure the method is called again next time it's accessed. I added None to the pop() to ensure this doesn't crash, since if it wasn't accessed, it won't be in __dict__. If you access it explicitly in your own code, then request.__dict__.pop('headers') is sufficient.
headers is a @cached_property so if it was accessed before you made the assignment, it wouldn't reflect the change.headers. Use META. And make sure no middleware that comes before yours accesses headers. Your middleware should be probably right at the top.
new_request = request.headers.copy(), and then modify the new request params.request.headersis a better way to access the headers that are contained inrequest.META. But it's read-only. So in fact, just modifyrequest.META['HTTP_FOO'].