codeigniter flatten array of query result

Question

I'm using a query in Codeigniter to return the ids of all the rows that belong to a user.

$this->db->select('id');
$this->db->where('user_id', 99);
$query = $this->db->get('my_table');
return $query->result_array();

This returns

Array ( [0] => Array ( [id] => 8 ) [1] => Array ( [id] => 7 ) [2] => Array ( [id] => 6 ) )

Is it possible to return a flat array like

Array ( [0] => 8 [1] => 6 [2] => 7 )

?

score 8 · Accepted Answer · edited Apr 25 '22 at 01:50

8

The CodeIgniter documentation (most particularly, query results) doesn't list anything that will produce a flat array result (like the PDO::FETCH_COLUMN mode provided for PDOStatement::fetchAll). As such, array results will need to be flattened in your code, such as with a foreach loop:

$flat = array();
foreach($query->result_array() as $row) {
    $flat[] = $row['id'];
}

or with the special purpose array_column:

array_column($query->result_array(), 'id');

or with the general purpose array_reduce:

array_reduce(
    $results, 
    fn ($accum, $row) => array_merge($accum, [$row['id']]),
    []);

If you're to lazy to add few lines each time you select one column, you would need to tweak CodeIgniter. Like adding some option or returning flattened array when single column is selected. I would suggest adding an option

edited Apr 25 '22 at 01:50

outis

75,655
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answered Sep 22 '12 at 17:20

Minimihi

408
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1

Thanks! I was hoping that codeignter had a built in function. – CyberJunkie Sep 22 '12 at 17:26
Wouldn't it be better to store the result of the function in a variable rather than calling the function each for loop? – user2019515 May 26 '13 at 03:41
Unless modifying by reference, `foreach()` "makes a copy" and plays with that. As a consequence of that behavior, the `result_array()` method is not called iteratively. @user2019515 – mickmackusa Oct 10 '19 at 00:13

score 0 · Answer 2 · answered Sep 02 '14 at 07:56

Following can be another way of dong it. I don't know what is the advantage of it over the accepted answer.

Let's say you are storing output of function in $result. Then you can do as following:

array_unshift($result, null);
$transposed = call_user_func_array("array_map", $result);
print_r($transposed);

It will print

Array( [0] => Array ( [0] => 8 [1] => 6 [2] => 7 ))

And you can access what you want by $transposed[0]

Array ( [0] => 8 [1] => 6 [2] => 7 )

codeigniter flatten array of query result

2 Answers2