Uploading Files with Drupal 6

Here's a relatively painless example for file uploads in Drupal 6.

This code is in a module file called usertab.module:

#create the form
function usertab_admin($form_state) {
    
  #prepare the file upload form
  $form = array('#attributes' => array('enctype' => 'multipart/form-data'));

  #file selector element
  $form['csv'] = array(
      '#type' => 'file',
      '#title' => 'Upload users',
      '#description' => t('Pick a csv file to upload')
  );

  #submit button
  $form['submit'] = array('#type' => 'submit', '#value' => 'Upload');
   return $form;
}

#handle the form submission
function usertab_admin_submit($form, &$form_state) {

  #this leads us to sites/mysite.example.com/files/
  $dir = file_directory_path();
 
  # unlike form submissions, multipart form submissions are not in 
  # $form_state, but rather in $FILES, which requires more checking
  if(isset($_FILES) && !empty($_FILES) && $_FILES['files']['size']['csv'] != 0)){
    
    #this structure is kind of wacky
    $name = $_FILES['files']['name']['csv'];
    $size = $_FILES['files']['size']['csv'];
    $type = $_FILES['files']['type']['csv'];

    #this is the actual place where we store the file
    $file = file_save_upload('csv', array() , $dir);
    if($file){
      drupal_set_message("You uploaded $name!");
    }
    else{
        drupal_set_message("Something went wrong saving your file.");
    }
  }
  else {
    drupal_set_message("Your file doesn't appear to be here.");
  }
}

Here are some of the strange things going on here:

First, the structure of the $_FILES array in php is kind of strange. There's a good diagram of it here: http://www.php.net/manual/en/features.file-upload.post-method.php#91479. Notice that it's the second one in the example.

Next, Drupal's (6) file_save_upload() method. The API documentation is here: http://api.drupal.org/api/drupal/includes--file.inc/function/file_save_upload/6, but the parameters can be kind of confusing so here are some details:

1. $source is the name of the file in the $_FILES array (also the name of the file field on form.
2. $validators are outside the scope of this example.
3. $dest is relative to the drupal root directory.
4. $replace is actually self-explanatory

P.S. At some point, I will figure out how to get some syntax highlighting going here.