Why might there be a bug in the fields of related Yii2 models?

Question

Yii

Given: 2 models (Building and Firm), one-to-one relationship (one firm can have 1 building)
In the Firm model, building data is displayed successfully

Model code Company

public function fields()
    {
        return [
            ...
            'building',
        ];
    }

    public function getBuilding()
    {
        return $this->hasOne(Building::className(), ['id' => 'building_id']);
    }

But if I want to display all the companies that it has near the building, then a server error falls

model code Building

public function fields()
    {
        return [
            ...
            'firms',
        ];
    }

    public function getFirms()
    {
        return $this->hasMany(Firm::className(), ['building_id' => 'id']);
    }

Answer 1

Try like this:

public function fields()
    {
        return [
            ...
            'firms' => function () {
                return $this->firms;
            },
        ];
    }

Answer 2

Well, logically, you are trying to select many records from another table for one record. I don’t remember exactly how yii2 reacts to this, but in Laravel such a feature will not work (Left join returns as many left records as right ones, this may be a problem with ORM).
You will have to force a call after $Build = Build::findOne(5) (or whatever); $BuildFirms = $Build->firms;