$query->result_array() wipes away list_fields() data - php

Question

I'm having an issue where I call the result_array() function on n query object from in codeigniter:
$this->db->select(array('a','b','c'));
$query = $this->db->get('basic');
print_r($query->list_fields());
$test = $query->result_array();
print_r($query->list_fields());
When I run this code, or:
$query = $this->db->get('basic');
print_r($query->list_fields());
print_r($query->list_fields());
or:
$query = $this->db->get('basic');
$test = $query->result_array();
print_r($query->list_fields());
The second list_fields() function always returns an array size 0, the first returns the correct list of field names.
In the last example where there is only one list_fields() function, the array is again size zero.
Any guidance in this matter will be greatly appreciated. I need the list_fields() function to be accessible after I read the result_array().
Here is the result of the first block of code:
Array
(
[0] => site_id
[1] => institution
[2] => caller
[3] => call_complete
[4] => call_details
[5] => id
[6] => timestamp
)
Array
(
)
Thank you, for your help

Answer 1

That looks to be a bug in the database driver. For example, in CI_DB_mysqli_result:
public function list_fields()
{
$field_names = array();
while ($field = $this->result_id->fetch_field())
{
$field_names[] = $field->name;
}
return $field_names;
}
A subsequent call will return array() because the while loop seeks over all the fields and leaves the pointer at the end of the list.
However, in the result class, result_id is public, so you can use mysqli_result::field_seek:
$query = $this->db->get('basic');
var_dump($query->list_fields());
// this should be called before any call to list_fields()
$query->result_id->field_seek(0);
var_dump($query->list_fields());
However, this is bad practise, as this only works for mysqli; for mysql, you'll need this:
mysql_field_seek($query->result_id, 0);
and for mssql:
mssql_field_seek($query->result_id, 0);
The correct way to do this is really to fix it in the database drivers. See this pull request :-)