protected function handleUpload()
    {
        $this->uploadedField = array_keys($_FILES)[0];
        //check if any uploaded file for a defined field
        $this->uploadOk = $this->checkUpload();
        if(!$this->uploadOk) {
            return;
        }
        //exec upload
        $this->uploadOk = $this->uploadFields[$this->uploadedField]->handleUpload($this->uploader);
        if(!$this->uploadOk) {
            return;
        }
        //outputs post processing
        $outputs = $this->uploadFields[$this->uploadedField]->getOutputsFiles();
        foreach($this->uploadFieldsDefinitions[$this->uploadedField]['outputs'] as $output => $outputDefinition) {
            if(isset($outputDefinition['processor'])) {
                $this->{$outputDefinition['processor']}($outputs[$output]['path']);
            }
        }
    }