Drupal 7 retain file upload - drupal

Question

I have a file upload form
how can I retain this file when there are other validation errors so that the user doesn't have to upload the file again?
I tried this in my validation function but it doesn't work:
function mymodule_someform_validate($form, &$form_state) {
$form_state["values"]["some_field"] = some_value;
}
the $form_state["values"] variable is not available in my form definition function - mymodule_someform($form, &$form_state)
Any ideas?

Answer 1

Just use the managed_file type, it'll do it for you:
$form['my_file_field'] = array(
'#type' => 'managed_file',
'#title' => 'File',
'#upload_location' => 'public://my-folder/'
);
And then in your submit handler:
// Load the file via file.fid.
$file = file_load($form_state['values']['my_file_field']);
// Change status to permanent.
$file->status = FILE_STATUS_PERMANENT;
// Save.
file_save($file);
If the validation fails and the user leaves the form, the file will be automatically deleted a few hours later (as all files in the file_managed table without FILE_STATUS_PERMANENT are). If the validation doesn't fail, the submit handler will be run and the file will be marked as permanent in the system.

Answer 2

Admin form example for others who may be looking:
function example_admin_form(){
$form = array();
$form['image'] = array(
'#type' => 'managed_file',
'#name' => 'image',
'#title' => t('upload your image here!'),
'#default_value' => variable_get('image', ''),
'#description' => t("Here you can upload an image"),
'#progress_indicator' => 'bar',
'#upload_location' => 'public://my_images/'
);
// Add your submit function to the #submit array
$form['#submit'][] = 'example_admin_form_submit';
return system_settings_form($form);
}
function example_admin_form_submit($form, &$form_state){
// Load the file
$file = file_load($form_state['values']['image']);
// Change status to permanent.
$file->status = FILE_STATUS_PERMANENT;
// Save.
file_save($file);
}