Help with ltree queries - Mailing list pgsql-general

From Tim Smith
Subject Help with ltree queries
Date
Msg-id CA+HuS5HaMBLM5Q0oJcOUX=t6jswTeoh1BKa0n7sheVL7FFsLDQ@mail.gmail.com
Whole thread Raw
List pgsql-general
Hi,

I'm trying to use PostgreSQL ltree to make a basic RBAC system as it
seems a sensible thing to do because of the hierarchical parsing ltree
can do !

I currently have the tables below which I've simplified as follows :

/***************
****************
****************
create table app_users (user_id char(64) not null primary key);
create table app_roles (role_id char(64) not null primary key);
create table app_user_role_memberships(
  user_id char(64) not null references app_users(user_id) on update
cascade on delete  cascade,
  role_id char(64) not null references app_roles(role_id) on update
cascade on delete cascade,
   primary key (user_id,role_id)
);
create table app_permissions (
    perm_id char(64) not null primary key,
    perm_label ltree not null);
create table app_role_perm_memberships (
    role_id char(64) not null references app_roles(role_id) on update
cascade on delete cascade,
    perm_id char(64) not null references app_permissions(perm_id) on
update cascade on delete cascade,
    primary key (role_id,perm_id)
);
****************
****************
****************/


The problem I have is whilst I've come up with the model above, I
can't seem to come up with a clean SQL query that doesn't look like
spaghetti !

Is my model correct ?  Are there better ways to do this (e.g. ltree[]
instead of ltree) ?

How clean can you make a query to find out whether a given user has
the correct permission for a resource ?

Thanks all !

Tim


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