Why does the Call to a member function load() on null error occur?

Question

Yii

Actually here is the code

$model= new Watch();
        if($this->classes == 'serial'){
                $feild='id_serial';
                $model= $model->id_serial;}
        if($this->classes == 'film'){
                 $feild='id_film';
                $model= $model->id_film;}
        if($this->classes == 'mfilm'){
                $feild='id_mfilm';
                $model= $model->id_mfilm;}
        $wathCount= Watch::find()->where(['id_serial'=>$this->serial->id,'active'=>1])->count();
        $guest=false;
        if ($model->load(Yii::$app->request->post()))
        { ...

swears at this line if ($model->load(Yii::$app->request->post()))

Answer 1

because you are overwriting the $model variable in three places

if($this->classes == 'serial'){
                $feild='id_serial';
                $model= $model->id_serial;} // тут
        if($this->classes == 'film'){
                 $feild='id_film';
                $model= $model->id_film;} // тут
        if($this->classes == 'mfilm'){
                $feild='id_mfilm';
                $model= $model->id_mfilm;} // тут

and at the time of calling $model->load() in the $model variable is no longer an object of the ActiveRecord class, but another value that does not have the load() method