= Yii 2 File Download =

Sometimes we need generated URLs to file downloads to avoid people bookmarking a permanent link to a file.

== Create Table ==

Example fields for table ''file'':
<code sql>
CREATE TABLE `file` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `file_path` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
  `hash` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
  `active` TINYINT(1) NOT NULL DEFAULT '1',
  PRIMARY KEY (`id`)
)
COLLATE='utf8_unicode_ci'
ENGINE=InnoDB
;
</code>

Create Active Record model for this table using Gii.

== Controller ==

Create action ''actionDownload()'' in controller.  When downloading, require a $hash as parameter:

<code php>
class FileController extends Controller
{
  //...
  
  public function actionDownload($hash)
  {
    $model = FileModel::find()->where(['hash'=>$hash])->one();
    
    if ($model && $model->active == 1) {
        $file = $model->file_path;
        $model->active = 0;
        $model->save(false);
        return $this->render('download', ['file' => $file]);
    }

    return $this->render('downloadLinkExpired');
  }
}  
</code>
    
== View ==    

<code php>
if (file_exists($file)) {
    Yii::$app->response->sendFile($file);
}
</code>

Then, in form controller 
  * Generate an MD5 hash based on current time and maybe some form fields (just to avoid duplicated hash). 
  * For every link, save new model in database. 
  * Render links with hash parameter. <code php>Url::toRoute('file/download', ['hash'=>$hash])</code>

Source: [[http://stackoverflow.com/questions/30977078/yii2-php-how-to-dynamically-generate-download-file-link-for-file-bigger-size-lik|StackOverflow: Yii2 - How to dynamically generate download file link]]