error yii2 upload Call to a member function saveAs() on null

问题

I am new programmer world and ask for your help guys, I have error "Call to a member function saveAs() on null"

This code in models

[['file'],'file'],

• this code in controllers

              $docfileload = $model->docname;
          $model->file = UploadedFile::getinstance($model,'file');
          $model->file->saveAs('uploads/'.$docfileload.'.'.$model->file->extension);
          $model->save();
  
          //save path in db
          $model->docfile = 'uploads/'.$docfileload.'.'.$model->file->extension;
  

this code in _form

    <?= $form->field($model,'file')->fileinput(); ?>

after I used getInstanceByName like @bluehipy told me I have a new issue look to the pic

enter image description here

回答1:

Try this one :

    $model->file=UploadedFile::getInstance($model,'file');  
    $model->pic=$model->file->extension; // pic is a field in database varchar(20)  
    $model->save(false) ;

    $ImageName=$model->id;
    if (!file_exists('uploads/'.$ImageName)) {
    mkdir('uploads/'.$ImageName, 0777, true);
        }   
    $model->file->saveAs( 'uploads/'.$ImageName.'/'.$ImageName.'.'.$model-
    >file->extension );

`

回答2:

UploadedFile::getinstance returns an array of files. Use getInstanceByName or UploadedFile::getinstance($model, 'file')[0].

来源：https://stackoverflow.com/questions/45902581/error-yii2-upload-call-to-a-member-function-saveas-on-null