How to display a one-to-many relationship in the fields() of a model?

Question

Yii

There are 3 models ( Building , Firm and Category )
I display in the fields of the Firm model the associated Building model like this:

public function fields()
    {
        return [
            'id',
            'name',
            'phones',
            'building',
        ];
    }

how to get the category ? Link generated by standard gii tools,

all communication methods

/**
     * @return \yii\db\ActiveQuery
     */
    public function getBuilding()
    {
        return $this->hasOne(Building::className(), ['id' => 'building_id']);
    }

    /**
     * @return \yii\db\ActiveQuery
     */
    public function getFirmCategories()
    {
        return $this->hasMany(FirmCategory::className(), ['firm_id' => 'id']);
    }

    /**
     * @return \yii\db\ActiveQuery
     */
    public function getCategories()
    {
        return $this->hasMany(Category::className(), ['id' => 'category_id'])->viaTable('{{%firm_category}}', ['firm_id' => 'id']);
    }

Answer 1

public function fields()
    {
        return [
            'id',
            'name',
            'phones',
            'building',
            'categories',
        ];
    }

Doesn't that work?