PHP Form Validation white space issue - php

Question

I am trying to validate a form. I have my code as follows:
if(isset($_POST['data'])) {
$id = $this->input->post('id');
$action = $this->input->post('action');
$table = $this->input->post('table');
$data = $this->input->post('data');
$out = array();
$out['id'] = $id;
$out['error'] = '';
$out['fieldErrors'] = '';
$out['data'] = array();
$out['row'] = $data;
if($action=="create" && $data['display_name'] === '') {
if (empty($data['display_name']))
{
$this->_out['error'] = "Display name is required";
echo json_encode( $this->_out );
exit;
}
}
}
Now this is working fine if there is no data inserted in the form, but if there is a space (whitespace) it doesn't work.
Any suggestion?

Answer 1

There are a few options to solve this:
Replace all whitespaces with nothing:
if (strlen(preg_replace('/\s/', '', $data['display_name'])) == 0)
{
Use trim to remove leading and trailing whitespaces:
if (strlen(trim($data['display_name'])) == 0)
{
Use str_replace() to get rid of invalid characters:
if (strlen(str_replace(array(' ', "\t"), array('', ''), $data['display_name'])) == 0)
{
Use regular expression to validate a name:
if (!preg_match('/^([A-Za-z0-9-_]+)$/', $data['display_name']))
{

Answer 2

=== checks for type as well along with value comparison, using trim function on variable containing values would give you expected results.

Answer 3

Try this. I have used the ctype_space function below to check for whitespaces
if($action=="create" && ($data['display_name'] === '' || ctype_space($data['display_name']))) {
$this->_out['error'] = "Display name is required";
echo json_encode( $this->_out );
exit;
}

Answer 4

Just use trim function and check if its empty string:
if ($action=="create") {
if (trim($data['display_name']) == '') {
$this->_out['error'] = "Display name is required";
echo json_encode( $this->_out );
exit;
}
}