Fix anon username from id (find renamed profile)

maybe related to #95, #104, 67ac8f3397.

docs/as-module.rst

@@ -74,7 +74,10 @@ metadata of a Profile. :class:`Profile` instances can be created with:
      profile = Profile.from_username(L.context, USERNAME)
 
 - :meth:`Profile_from_userid`
-   given its User ID (currently requires to be logged in).
+   given its User ID. This allows to easily lookup a Profile's username given
+   its ID::
+
+      Profile.from_id(L.context, USERID).username
 
 - :meth:`Profile.get_followees`
    Profiles that are followed by given user.

instaloader/instaloader.py

@@ -629,10 +629,6 @@ class Instaloader:
                 else:
                     self.context.log("Trying to find profile {0} using its unique ID {1}.".format(profile_name,
                                                                                                   profile_id))
-                if not self.context.is_logged_in:
-                    self.context.error("Profile {} changed its name. "
-                                       "If you use --login=USERNAME, I can find out the new name.")
-                    raise LoginRequiredException("--login=USERNAME required to obtain profile name from its ID number")
                 profile_from_id = Profile.from_id(self.context, profile_id)
                 newname = profile_from_id.username
                 self.context.log("Profile {0} has changed its name to {1}.".format(profile_name, newname))

instaloader/instaloadercontext.py

@@ -56,6 +56,7 @@ class InstaloaderContext:
         self.quiet = quiet
         self.max_connection_attempts = max_connection_attempts
         self._graphql_page_length = 50
+        self._root_rhx_gis = None
 
         # error log, filled with error() and printed at the end of Instaloader.main()
         self.error_log = []
@@ -376,3 +377,14 @@ class InstaloaderContext:
             except KeyboardInterrupt:
                 self.error("[skipped by user]", repeat_at_end=False)
                 raise ConnectionException(error_string) from err
+
+    @property
+    def root_rhx_gis(self) -> Optional[str]:
+        """rhx_gis string returned in the / query."""
+        if self.is_logged_in:
+            # At the moment, rhx_gis seems to be required for anonymous requests only. By returning None when logged
+            # in, we can save the root_rhx_gis lookup query.
+            return None
+        if not self._root_rhx_gis:
+            self._root_rhx_gis = self.get_json('', {})['rhx_gis']
+        return self._root_rhx_gis

instaloader/structures.py

@@ -145,8 +145,8 @@ class Post:
             else:
                 # Sometimes, the 'owner' structure does not contain the username, only the user's ID.  In that case,
                 # this call triggers downloading of the complete Post metadata struct, where the owner username
-                # is contained. This is better than to get the username by user ID, since it is possible anonymously
-                # and gives us other information that is more likely to be usable.
+                # is contained. This is better than to get the username by user ID, since it
+                # gives us other information that is more likely to be usable.
                 owner_struct = self._full_metadata['owner']
             if 'username' in owner_struct:
                 self._owner_profile = Profile(self._context, owner_struct)
@@ -379,17 +379,16 @@ class Profile:
 
     @classmethod
     def from_id(cls, context: InstaloaderContext, profile_id: int):
-        """If logged in, create a Profile instance from a given userid. If possible, use :meth:`Profile.from_username`
-        or constructor directly rather than this method, since does many requests.
+        """Create a Profile instance from a given userid. If possible, use :meth:`Profile.from_username`
+        or constructor directly rather than this method, since it does many requests.
 
         :param context: :attr:`Instaloader.context`
         :param profile_id: userid
-        :raises: :class:`ProfileNotExistsException`, :class:`LoginRequiredException`, :class:`ProfileHasNoPicsException`
+        :raises: :class:`ProfileNotExistsException`, :class:`ProfileHasNoPicsException`
         """
-        if not context.is_logged_in:
-            raise LoginRequiredException("--login=USERNAME required to obtain profile metadata from its ID number.")
         data = context.graphql_query("472f257a40c653c64c666ce877d59d2b",
-                                     {'id': str(profile_id), 'first': 1})['data']['user']
+                                     {'id': str(profile_id), 'first': 1},
+                                     rhx_gis=context.root_rhx_gis)['data']['user']
         if data:
             data = data["edge_owner_to_timeline_media"]
         else:
@@ -400,7 +399,7 @@ class Profile:
                 raise ProfileHasNoPicsException("Profile with ID {0}: no pics found.".format(str(profile_id)))
             else:
                 raise LoginRequiredException("Login required to determine username (ID: " + str(profile_id) + ").")
-        username = Post.from_mediaid(context, int(data['edges'][0]["node"]["id"])).owner_username
+        username = Post.from_shortcode(context, data['edges'][0]["node"]["shortcode"]).owner_username
         return cls(context, {'username': username.lower(), 'id': profile_id})
 
     def _asdict(self):

test/instaloader_unittests.py

@@ -54,6 +54,10 @@ class TestInstaloaderAnonymously(unittest.TestCase):
         self.assertEqual(PUBLIC_PROFILE_ID,
                          instaloader.Profile.from_username(self.L.context, PUBLIC_PROFILE).userid)
 
+    def test_get_username_by_id(self):
+        self.assertEqual(PUBLIC_PROFILE.lower(),
+                         instaloader.Profile.from_id(self.L.context, PUBLIC_PROFILE_ID).username)
+
     def test_post_from_mediaid(self):
         for post in instaloader.Profile.from_username(self.L.context, PUBLIC_PROFILE).get_posts():
             post2 = instaloader.Post.from_mediaid(self.L.context, post.mediaid)