'integer', ]; public function sourceArtwork(): BelongsTo { return $this->belongsTo(Artwork::class, 'source_artwork_id'); } public function targetArtwork(): BelongsTo { return $this->belongsTo(Artwork::class, 'target_artwork_id'); } public function creator(): BelongsTo { return $this->belongsTo(User::class, 'created_by_user_id'); } }