'array', 'extracted_metadata' => 'array', 'created_at' => 'datetime', 'updated_at' => 'datetime', ]; public function papers(): HasMany { return $this->hasMany(SourcePaper::class); } public function parts(): HasManyThrough { return $this->hasManyThrough(PaperPart::class, SourcePaper::class); } public function candidates(): HasMany { return $this->hasMany(PreQuestionCandidate::class); } }