Can update following status of a group membership.

RestControllers/GroupsController.php

@@ -626,6 +626,28 @@ class GroupsController {
 		return array("success" => "Your membership has been successfully deleted!");
 	}
 
+	/**
+	 * Set whether a user is following a group or not
+	 * 
+	 * @url POST groups/set_following
+	 */
+	public function setFollowing(){
+		user_login_required();
+
+		//Get the group
+		$groupID = getPostGroupIdWithAccess("groupID", GroupInfo::MEMBER_ACCESS);
+
+		//Get following status
+		$following = postBool("follow");
+
+		//Save the new value
+		if(!components()->groups->setFollowing($groupID, userID, $following))
+			Rest_fatal_error(500, "Could not update following status!");
+		
+		//Success
+		return array("success" => "Follow status has been successfully updated!");
+	}
+
 	/**
 	 * Parse a GroupInfo object into an array for the API
 	 * 

classes/components/GroupsComponent.php

@@ -622,6 +622,22 @@ class GroupsComponent {
 			return $groupID == $currID;
 	}
 
+	/**
+	 * Set (update) user following status
+	 * 
+	 * @param int $groupID Target group ID
+	 * @param int $userID Target user ID
+	 * @param bool $following New following status
+	 * @return bool TRUE to follow / FALSE else
+	 */
+	public function setFollowing(int $groupID, int $userID, bool $following) : bool {
+		return db()->updateDB(
+			self::GROUPS_MEMBERS_TABLE, 
+			"groups_id = ? AND user_id = ?",
+			array("following" => $following ? 1 : 0),
+			array($groupID, $userID));
+	}
+
 	/**
 	 * Turn a database entry into a GroupInfo object
 	 *