Form validation on radio buttons Codeigniter - codeigniter

Question

I am trying to add validation for radio buttons on a html form in Codeigniter. The form is prepopulated with data from a database, including a list of uploaded documents (this field may be empty if the item has no associated docs). The user can upload a new document, adding it to the existing docs or adding a new doc deleting the current ones.
So I have a text field containing the org doc names and a file upload field for new:
<label for="orgdocs">Documents</label>
<input type="text" id="orgdocs" readonly="readonly" value="<?php echo $fetched_row['pdocs']; ?>" />
<input type="file" id="newdocs" name="newdocs[]" multiple="multiple" />
and radio buttons: (ignore the bad attempt at Spanish names)
<label for="mas"><b>Añada mas</b></label>
<input type="radio" name="docsacion" style="margin-right: 0" <?php if (isset($docsacion) && $docsacion=="mas") echo "checked";?> value="mas" title="Add another document to existing docs"><br />
<label for="otra"><b>Borrar y añada otra</b></label>
<input type="radio" name="docsacion" style="margin-right: 0" <?php if (isset($docsacion) && $docsacion=="otra") echo "checked";?> value="otra" title="Remove all current docs and add new">
I just want to add validation. IF a new document has been selected(newdocs is not empty), dosacion is required.
I have tried:
if(isset($_FILES['newdocs']['name']) && (!empty($_FILES['newdocs']['name'])))
{$this->form_validation->set_rules('docascion','Documentation upload', 'required');}
but this gives the error even if the newdocs field is empty and I´ve no idea why!?

Answer 1

Try this
if(!empty($_FILES['newdocs']['name'])){
$this->form_validation->set_rules('docascion','Documentation upload', 'required');
}