How to make header rows optional ? causing issue of undefined key

[ahmadkureshi]

hello i would like to know sis there any way to validate the heading row like on my import
i have this code
public function model(array $row)
{
return new ProspectsRecord([
'prospects_id' => $this->prospects_id,
'email' => $row['email'],
'address' => $row['address'],
'city' => $row['city'],
'state' => $row['state'],
'zip_code'=>$row['zip_code'],
'contact'=>$row['contact']
]);
}

some of the fields are optional and allowing the user to import without header of column-like state  but it is throwing error undefined index state( how i can make my header optional) please help i shall be thankful