PDO - Duplicate entry on file upload

Question

I'm developing a module that uploads CSV file.

/**
 * Implements hook_menu().
 */
function geo_points_menu(){
    $items['geo-points-upload'] = array(
        'title' => 'Geo points',
        'description' => 'Upload users',
        'page callback' => 'drupal_get_form',
        'page arguments' => array('geo_points_form'),
        'access arguments' => array('access content'),
        'access callback' => TRUE,
        'type' => MENU_NORMAL_ITEM,
        'menu_name' => 'main-menu',
    );

    return $items;
}

function geo_points_form($form, &$form_state) {
    $form = array();

    // Use the #managed_file FAPI element to upload a file.
    $form['file_fid'] = array(
        '#title' => t('File'),
        '#type' => 'managed_file',
        '#description' => t('The uploaded file will be processed.'),
        '#default_value' => variable_get('file_fid', ''),
        '#upload_validators' => array(
            'file_validate_extensions' => array('csv'),
        ),
        '#upload_location' => 'public://csv_uploads',
        '#process' => array('geo_points_my_file_element_process')
    );

    $form['buttons']['submit'] = array(
        '#type' => 'submit',
        '#value' => t('Import'),
    );

    return $form;
}

/* It disables the default upload button that comes with this #managed_file form */
function geo_points_my_file_element_process($element, &$form_state, $form) {
    $element = file_managed_file_process($element, $form_state, $form);
    $element['upload_button']['#access'] = FALSE;

    return $element;
}

function geo_points_form_submit(&$form, &$form_state) {
    // Load the file.
    $file = file_load($form_state['values']['file_fid']);
    dpm(csv_to_array($file->uri));
    file_usage_delete($file, 'geo_points');
//    // Change status to permanent.
//    $file->status = FILE_STATUS_PERMANENT;
//    // Save.
//    $uploaded = file_save($file);
//    if ($uploaded == TRUE) {
//        dpm(csv_to_array($file->uri));
//    }
//    else {
//        drupal_set_message(t('The file could not be uploaded. Please contact the site administrator.'), 'error');
//    }

    //$file_path = $file->uri;

    //Function call to process file contents.
    //csv_import_create_node($file_path);

}

/**
 * @param string $filename
 * @param string $delimiter
 * @return array|bool
 */
function csv_to_array($filename='', $delimiter=',')
{
    if(!file_exists($filename) || !is_readable($filename))
        return FALSE;

    $header = NULL;
    $data = array();
    if (($handle = fopen($filename, 'r')) !== FALSE)
    {
        while (($row = fgetcsv($handle, 1000, $delimiter)) !== FALSE)
        {
            if(!$header)
                $header = $row;
            else
                $data[] = array_combine($header, $row);
        }
        fclose($handle);
    }
    return $data;
}

When I upload the same file more than one time I'm getting the following exception:

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'public://csv_uploads/points2014-01-16T14-22-48.csv' for key 'uri': INSERT INTO {file_managed} (uid, filename, uri, filemime, filesize, status, timestamp) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6); Array ( [:db_insert_placeholder_0] => 1 [:db_insert_placeholder_1] => points2014-01-16T14-22-48.csv [:db_insert_placeholder_2] => public://csv_uploads/points2014-01-16T14-22-48.csv [:db_insert_placeholder_3] => text/csv [:db_insert_placeholder_4] => 84 [:db_insert_placeholder_5] => 0 [:db_insert_placeholder_6] => 1390315536 ) in drupal_write_record() (line 7170 of C:\wamp\www\drupal7_poc2\includes\common.inc).

I have 2 questions:
1. How avoid this exception. 2. After I upload the file and read it's content I don't the file anymore, can I read the stream only without saving the file?

Answer 1

1. Use a try...catch block and recover in whatever way makes most sense to your application.
2. The file is already on the disk by the time you get access to it (in the /tmp folder), so no. If you don't explicitly choose to keep it, it will be deleted either by a system job or the system module's cron run.