PHP, MySQL - efficiently determining access permissions based on distant parent - php

Question

I'm struggling to come up with an efficient solution to determine user access to a specified folder, using PHP (specifically Laravel) and MySQL. I want to create a system that has Google Drive-esque functionality...
For example, Joe Bloggs creates many folders within folders, e.g. Level 1 > Level 2 > Level 3 > Level 4 > Level 5. Within any of these folders, can be any number of additional sub files and folders.
This would be the resulting database structure -
Table name: users
| id | name |
| -- | ---------- |
| 1 | Joe Bloggs |
| 2 | John Snow |
Table name: folders
| id | parent_id | author_id | name |
| -- | --------- | --------- | --------- |
| 1 | NULL | 1 | Level 1 |
| 2 | 1 | 1 | Level 2 |
| 3 | 2 | 1 | Level 3 |
| 4 | 3 | 1 | Level 4 |
| 5 | 4 | 1 | Level 5 |
| 6 | 2 | 1 | Level 3.1 |
| 7 | 2 | 1 | Level 3.2 |
Table name: folders_users
| id | folder_id | user_id | owner | read | write |
| 1 | 1 | 1 | 1 | 1 | 1 |
| 2 | 3 | 2 | 0 | 1 | 1 |
So based on record 1 in folder_users, Joe Bloggs should have owner, read & write permissions for all folders underneath Level 1. Joe Bloggs, then gives John Snow read & write access to Level 3, which in turn should give Joe Bloggs read & write access to Level 3, Level 3.1, Level 3.2 and anything created under any of these in future.
Additionally, it should be possible for a user to star a folder. I'd imagine this can simply be achieved with a separate table and query this separately -
Table name: starred_folders
| id | folder_id | user_id |
| -- | --------- | ------- |
| 1 | 7 | 2 |
The current solution I have is for every folder in the chain a user has permission to access, a record is created in the folders_users table. I feel like this is just overcomplicating things and creating excessive numbers of records. This is especially true when it comes to sharing a folder as I have to recreate the entire tree for that one user. Or, imagine if a user revokes write access to one of the shared users, the entire tree (potentially hundreds of records) has to be updated for a single flag.
What would be the best way to generate these trees, and to quickly and efficiently determine the user's access level in any given folder? I suspect the only way to do this is recursion, but I'm concerned about its efficiency? Or, should I perhaps be using something entirely different from MySQL for this? I've had a brief look into graph databases but I can't see it being a way forward for us as we don't have the infrastructure to support it.
Thanks,
Chris.

Answer 1

I'm writing this as a solution not the most efficient one.
You can add a column to your folders table (let's call it access) and then put ids of people that have access to that folder and it's children. I assume when you want to show information about a folder you must get its parents information from table as well so you won't need to add new queries for that.
And if you just have a access definition you can simple add records to this column like user1,user2,... and if not you can serialize an array like this
[
"read" => [user1,user2,...],
"write" => [user2]
]
Of course you can add a column for each access but if you have so many accesses this might be a solution too.