Call to a member function saveAs() on a non-object in yii2

Question

I am trying to run an application in Yii2 I tried to upload a user profile picture and it works greatly but the problem starts when I try to update the name file. It shows me an error like Call to a member function saveAs() on a non-object. I even tried to update without any changes.. even that time also show me the same error... but error goes if I change the pic. this is my controller

public function actionUpdate($id)
{
    $model = $this->findModel($id);

    if ($model->load(Yii::$app->request->post()) && $model->save()) {

        // get the instance of uploaded file
        $imageName = $model->user_username;
        $model->file = UploadedFile::getInstance($model,'user_avatar');

        $model->file->saveAs( '/uploads/'.$imageName.'.'.$model->file->extension );

        //save the path in DB..
        $model->user_avatar = 'uploads/'.$imageName.'.'.$model->file->extension;
        $model->save();

        return $this->redirect(['view', 'id' => $model->user_id]);
    } else {
        return $this->render('update', [
            'model' => $model,
        ]);
    }
}

The model rules

  public function rules()
            {
                return [

                [['user_email', 'user_password'], 'required'],
                    // [['user_password'], 'required'],
                    [['user_username'], 'string', 'max' => 45],
                    [['user_first_name'], 'required'],
                    [['user_app_user_id'], 'required',
                    [['user_type','user_app_name','user_status'], 'string'],
                    [['user_app_user_id'], 'integer'],
                    [['user_rememberMe'], 'boolean'],
                    [['user_first_name', 'user_last_name'], 'string', 'max' => 100],
                    [['user_email'], 'string', 'max' => 150],
                    [['user_password'], 'string', 'min'=>6],
                    [['user_password'], 'string', 'max' => 40,
                    [['user_avatar'],'file'],
                    //[['user_avatar'], 'string', 'max' => 500],
                    [['user_verification_code','user_auth_key'], 'string'],
                    [['user_email'], 'email'],
                    [['user_email'], 'filter', 'filter' => 'trim'],

                    ];
            }

Answer 1

Your code requires file upload. You should just add condition here:

if ($model->file = UploadedFile::getInstance($model,'user_avatar')) {
    $model->file->saveAs( '/uploads/'.$imageName.'.'.$model->file->extension );
    //save the path in DB..
    $model->user_avatar = 'uploads/'.$imageName.'.'.$model->file->extension;
    $model->save();
}