Follow Relation¶

Nene\Kit\FollowRelation — directed user follow/unfollow relationships with mutual-follow detection.

Schema¶

CREATE TABLE follow_relations (
    follower_id VARCHAR(255) NOT NULL,
    followee_id VARCHAR(255) NOT NULL,
    created_at  DATETIME     NOT NULL DEFAULT CURRENT_TIMESTAMP,
    PRIMARY KEY (follower_id, followee_id)
);
CREATE INDEX idx_follow_relations_followee ON follow_relations (followee_id);

The composite primary key (follower_id, followee_id) ensures uniqueness and serves as the main lookup index. The secondary index on followee_id speeds up followers() queries.

API¶

Method	Description
`follow(string $followerId, string $followeeId): bool`	Follow a user. Returns `true` on success, `false` if already following or self-follow attempt.
`unfollow(string $followerId, string $followeeId): bool`	Unfollow a user. Returns `true` if removed, `false` if not following.
`isFollowing(string $followerId, string $followeeId): bool`	Check whether $followerId follows $followeeId.
`followers(string $userId): array`	List users following $userId.
`following(string $userId): array`	List users $userId follows.
`isMutual(string $userA, string $userB): bool`	Check whether both users follow each other.

Usage¶

$fr = new FollowRelation($pdo);

// Follow
$fr->follow('user:1', 'user:2');   // true
$fr->follow('user:1', 'user:2');   // false — already following
$fr->follow('user:1', 'user:1');   // false — self-follow

// Check
$fr->isFollowing('user:1', 'user:2');  // true
$fr->isFollowing('user:2', 'user:1');  // false — directional

// Lists
$fr->followers('user:2');   // [['follower_id' => 'user:1', 'created_at' => '...']]
$fr->following('user:1');   // [['followee_id' => 'user:2', 'created_at' => '...']]

// Mutual follow
$fr->follow('user:2', 'user:1');
$fr->isMutual('user:1', 'user:2');  // true

// Unfollow
$fr->unfollow('user:1', 'user:2');  // true
$fr->unfollow('user:1', 'user:2');  // false — not following

Key design points¶

Self-follow prevention: follow($id, $id) returns false without touching the DB.
Idempotent follow: INSERT OR IGNORE / INSERT IGNORE — duplicate follow is a no-op returning false.
Directional: A→B does not imply B→A. isFollowing reflects only the stated direction.
isMutual symmetry: isMutual(A, B) === isMutual(B, A).
No framework dependency: Constructor accepts ?PDO, falls back to PdoConnection::getInstance().

Test patterns¶

$db = new PDO('sqlite::memory:');
$db->exec('CREATE TABLE follow_relations (
    follower_id VARCHAR(255) NOT NULL,
    followee_id VARCHAR(255) NOT NULL,
    created_at  DATETIME     NOT NULL DEFAULT CURRENT_TIMESTAMP,
    PRIMARY KEY (follower_id, followee_id)
)');
$fr = new FollowRelation($db);