CODEWITHSUNDEEP
phpmysql
mister martin
mister martin

Reputation: 6252

Selecting a users forum activity while limiting results based on permission

I have a forum split into multiple tables: categories, topics and threads.

CREATE TABLE forum_categories (
  cat_id INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
  role_id INTEGER UNSIGNED NOT NULL DEFAULT 0,
  cat_name VARCHAR(50) NOT NULL,

  PRIMARY KEY(cat_id),
  FOREIGN KEY (role_id)
    REFERENCES roles(role_id)
);
CREATE TABLE forum_topics (
  topic_id INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
  cat_id INTEGER UNSIGNED NOT NULL,
  topic_name VARCHAR(50) NOT NULL,
  topic_desc VARCHAR(100) NOT NULL,

  PRIMARY KEY(topic_id),
  FOREIGN KEY (cat_id)
    REFERENCES forum_categories(cat_id)
);
CREATE TABLE forum_threads (
  thread_id INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
  parent_id INTEGER UNSIGNED NOT NULL DEFAULT 0,
  topic_id INTEGER UNSIGNED NOT NULL,
  user_id INTEGER UNSIGNED NOT NULL,
  title VARCHAR(100) NOT NULL,
  body TEXT NOT NULL,
  create_date DATETIME NOT NULL,

  PRIMARY KEY (thread_id),
  FOREIGN KEY (parent_id)
    REFERENCES forum_threads(thread_id),
  FOREIGN KEY (topic_id)
    REFERENCES forum_topics(topic_id),
  FOREIGN KEY (user_id)
    REFERENCES users(user_id)
);

The category table has a field named role_id, which if set to any value other than 0 means that only users with that role are allowed to view or interact with the topics in that category.

The problem I'm facing is when attempting to pull a specific users recent activity for everyone to see. I want to COUNT(*) on the threads table containing the requested user_id, but I need to exclude threads having a topic_id associated with a restricted category unless the user requesting the information has permission.

If viewing a specific thread, I would simply extract the topic_id and check like this:

// validate topic id and check for permission
$forum = new Forum();
$valid_topics = $forum->getTopics();
if (!array_key_exists($topic_id, $valid_topics)) {
    // invalid topic id
}
$valid_categories = $forum->getCategories();
$role_id = $valid_categories[$valid_topics[$topic_id]['cat_id']]['role_id'];
if ($role_id == 0 || array_key_exists($role_id, $session_user_roles)) {
    // user has permission
}

Now I'm trying to convert my PHP logic into SQL. Here is a pseudo-code example of what I'm after:

SELECT COUNT(*),
  (SELECT role_id,
     (SELECT cat_id
        FROM forum_topics AS t2
        WHERE topic_id = t1.topic_id) AS cat_id
     FROM forum_categories
     WHERE cat_id = t2.cat_id) AS role_id
  FROM forum_threads AS t1
  WHERE user_id = $user_id AND (role_id != 0 OR FIND_IN_SET(role_id, $session_user_roles) > 0)

Any help, please?

Upvotes: 0

Views: 30

Answers (1)

krokodilko
krokodilko

Reputation: 36107

Try this way

SELECT count(*)
FROM forum_threads thr
JOIN forum_topics top    ON thr.topic_id = top.topis_id 
JOIN forum_categories fc ON top.cat_id = fc.cat_id 
WHERE thr.user_id = $user_id
    AND fc.role_id IN ( 0,     24, 55, 888, .... list of user roles ... )

In the list of user roles (last condition) always put 0 as a first number, then the rest of his roles.

Upvotes: 1

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