Add custom validator to a filefield
Sometimes, it might be necessary to add validation code to a filefield field. For example, in case you allow uploading a very specific file type, you might want to check that the user is uploading a valid file and not just one with the correct file extension. In order to do so, a validator must be added to filefield.
This can be done by changing (altering) the code of the form, which includes the filefield. Therefore, you have to implement hook_form_alter() in a custom module:
function example_form_alter(&$form, $form_state, $form_id) {
if ($form_id != 'ID_OF_YOUR_FORM')
return;
$form['FIELDNAME'][0]['#upload_validators']['example_FUNCTIONNAME'] = array();
return $form;
}Now, the validator function must be provided, too.
function example_FUNCTIONNAME($field) {
// variable for error messages
$errors = array();
// do some processing on the field
$filepath = $field->filepath;
...
// in case of error, add error message
$errors[] = t('Validation failed, because...');
return $errors;
}It is important that your module gets processed after the modules filefield and CCK. If your module is processed before, the filefield code won't be present in the $form variable in hook_form_alter(...) and it is impossible to add a validation handler. The processing order of modules is controlled by their weight stored in the {system} table. The example module must have a larger value than content (CCK) and filefield. See http://drupal.org/node/110238 for details on how to adjust the weight value.
hi there, i need to validate
hi there,
i need to validate a file field. this is my first custom module, so maybe i just miss something very trivial...
actually there is no real validation yet but i just return $errors[] = t('Validation Error'); so in my understanding there should be an error everytime i save the node
unfortunately the code doesn't seem to work.
function upload_duration_form_alter(&$form, $form_state, $form_id) {//if ($form_id != 'page_node_form')
// return;
$form['field_videoclip'][0]['#upload_validators']['upload_duration_ckeckduration'] = array();
return $form;
function upload_duration_checkduration($field) {$errors = array();
$errors[] = t('Validation Error');
return $errors;
thank you for any suggestions?
edit:
i set the module weight to 99 with the util module.
solved
i don't know exactly what was wrong with my code, but the additional validation is now working. thanks for your code snipplets :)