Valid extensions for the upload field on Drupal 7

Question

I need to make a form to upload a CSV file. I get the following error when I try to use the form item below:

Only files with the following extensions are allowed: jpg jpeg gif png txt doc xls pdf ppt pps odt ods odp.

  $form['data_file'] = array(
    '#type' => 'file',
    '#title' => t('Data File'),
    '#description' => t('CSV file to upload.'),
    '#upload_validators' => array(
      'file_validate_extensions' => array('csv'),
      'file_validate_size' => array(32*1024*1024),
    ),
  );

How can I let a CSV file pass through the validator?

Answer 1

I was able to do it with the following code in the form validation hook.

function mymodule_myform_validate($form, $form_state) {
  $validators = array('file_validate_extensions' => array('csv'));
  $file = file_save_upload('zipdata_file', $validators);
  ...
}

Answer 2

If you look at The forms API reference this comment explains how to do it.

I can't exactly test it out, but possibly something like this

  $form['data_file'] = array(
    '#type' => 'file',
    '#title' => t('Data File'),
    '#description' => t('CSV file to upload.'),
    '#upload_validators' => array(
      'file_validate_extensions' => array(0 => 'csv'),
      'file_validate_size' => array(32*1024*1024),
    ),
  );

Answer 3

Your form function

// don't forget this line
$form['#attributes'] = array('enctype' => "multipart/form-data");

$form['container']['csv_file'] = array(
'#type' => 'file' ,  
'#title' => t('csv FILE') , 
'#description' => t('insert your csv file here') , 
) ; 

Your validate function

function _your_function_validate($form, $form_state) {
$extensions = 'csv' ; 
$validators = array(
 'file_validate_extensions' => array($extensions),
);
// if the file not uploaded or the extension is wrong set error
if(!file_save_upload('csv_file', $validators)) { // cvs_file is the form name
  form_set_error('csv_file', 'Please select the csv file') ;    
}else{ 
// now the form is uploaded lets make another validation for extension
  $file = file_save_upload('csv_file', $validators, file_directory_path()) ; 

// another validator for the extension
if($file->filemime != 'text/csv' ) {
 form_set_error('csv_file', 'Extensions Allowed : csv') ;       
}       
}       
}