id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
30024	The test client request methods should raise an error when passed None as a data value	Jon Dufresne	nobody	"Both GET and POST encoded data do not have a concept of `None` or `NULL`. The closest approximation is an empty string value or omitting the key. For example, in a GET request this could be either `/my-url/?my_field=` or simply `/my-url/` but not `/my-url/?my_field=None`)

When onboarding new developers to projects, this can cause confusion to those less familiar with these details. For example, a new developer may try the following:

{{{
def test_setting_value_to_none(self):
    self.client.post('/my-url/', {'my_field': None})
    self.assertIsNone(...)
}}}

In current versions of Django, behind the scenes, this `None` gets coerced to the string `'None'` by the test client. The Django form field classes don't recognize the string `'None'` as an empty value (good) and so this test doesn't pass. Where the new developer thought a field would be assigned `None` they instead get a form error. Depending on the developers' knowledge of these details, this could take much debugging or consulting a colleague.

I think we can recognize this pattern as a programming mistake and raise an informative error to guide the developer. I propose something like the following, but am open to suggestions:

{{{
TypeError: Cannot encode None as POST data. Did you mean to pass an empty string or omit the value?
}}}

For GET requests, the query string data is processed by `django.utils.http.urlencode()`. So perhaps this same check can be done there as encoding `None` in a URL query string as `'None'` is rarely the intended behavior. For those that really want the string `'None'` in the query string, they can pass the string `'None'`.
"	New feature	closed	Testing framework	dev	Normal	fixed			Ready for checkin	1	0	0	0	0	0