The original semantic of OR is defined as: the request pass either of the two has_permission() check, and pass either of the two has_object_permission() check, which could lead to situations that a request passes has_permission() but fails on has_object_permission() of Permission Class A, fails has_permission() but passes has_object_permission() of Permission Class B, passes the OR permission check. This should not be the desired permission check semantic in applications, because such a request should fail on either Permission Class (on Django object permission) alone, but passes the OR or the two.
My code fix this by changing the semantic so that the request has to pass either class's has_permission() and has_object_permission() to get the Django object permission of the OR check.
* Introspect ManyRelatedField data type recursively
For all `ManyRelatedField` objects, we were assuming that the inner type was always a `String`. While this may be true for the default output, a `ManyRelatedField` is a wrapper for a lot of other classes which includes more than just strings. This should allow us to document lists of things other than strings.
* Added test for schemas for many-to-many fields
This adds a test that makes sure we generate the schema for a many-to-many field such that it actually has the right type. For some reason we did not previously have any tests for schema generation that included them, so hopefully this will prevent any future issues from popping up.
This should serve as a regression test for the `items` field on to-many relationships, which was previously forced to a `String` even though in most cases it is a different inner type within the array.
As all source files import unicode_literals, type('') is always
equivalent to six.text_type (str on Python 3 and unicode on Python 2).
Removes the need to call type(), is more explicit, and will be easier to
catch places to change for when it is time to eventually drop Python 2.
* Use compat version of collections.abc.Mapping
Since the Mapping class will no longer be available to import directly
from the collections module in Python 3.8, we should use the
compatibility helper introduced in #6154 in the fields module.
* Alias and use compat version of collections.abc.MutableMapping
Since the MutableMapping class will no longer be available to import
directly from the collections module in Python 3.8, we should create an
alias for it in the compat module and use that instead.
