Question

I’m having difficulty constructing a multidimensional array based on queries fetched from a mysql database. The purpose is to prepare the result for json encoding. Having problems here.

Structure I’m aiming for:

Array ( 
    [68] => Array ( 
        [0] => Array ( 
            [id] => 64 
            [description] => yada, yada, yada... ) 
        [1] => Array ( 
            [id] => 65 
            [description] => yada, yada, yada...) 
        [2] => Array ( 
            [id] => 66 
            [description] => yada, yada, yada... ) ) 
    [69] => Array ( 
        [0] => Array ( 
            [id] => 64 
            [description] => yada, yada, yada... ) 
        [1] => Array ( 
            [id] => 65 
            [description] => yada, yada, yada...) 
        [2] => Array ( 
            [id] => 66 
            [description] => yada, yada, yada... ) ) 
...etc
)

From:

//this is a list of unknown length
$array_ids = (68, 69, 70, etc... );   // or:

Array ( 
    [0] => 68 
    [1] => 69
    [2] => 70 
    [3] => 71 
    etc..  
)


//this is a known length 
$array_contents = ( array ( array ( [id], [description]) );  // or:

Array ( 
    [0] => Array ( 
        [id] => 64 
        [description] =>yada, yada, yada... ) 
    [1] => Array ( 
        [id] => 65 
        [description] => yada, yada, yada... ) 
    [2] => Array ( 
        [id] => 66 
        [description] => yada, yada, yada... ) )

My attempt:

foreach($array_ids as $row){
    $result = array($row=>array());
    foreach($array_contents as $key => $value){
        $result [$row][$key] = $value;
    }
}

Result:

Array ( 
    [68] => Array ( 
        [0] => Array ( 
            [id] => 64 
            [description] => yada, yada, yada... ) 
        [1] => Array ( 
            [id] => 65 
            [description] => yada, yada, yada...) 
        [2] => Array ( 
            [id] => 66 
            [description] => yada, yada, yada... ) ) 

)

…and that’s where it stops. It doesn’t go on to the next row id of 69, 70, etc…

What am I doing wrong?

Answer 1

This line seems to be the problem:

$result = array($row=>array());

Every pass through $array_ids it’s completely wiping out $result and repopulating it with one single item from $array_contents, rather than appending it to the end.

Replacing it with this should work:

$result[$row] = array();

Here’s a full working version:

$array_ids = array(68,69,70);

$array_contents = array(
    array( 
        'id' => 64, 
        'description' => 'yada, yada, yada...'
    ),
  array( 
        'id' => 65,
        'description' => 'yada, yada, yada2...'
    ),
    array( 
    'id' => 66,
    'description' => 'yada, yada, yada3...'
    ),
);

foreach($array_ids as $row){
    $result[$row] = array();
    foreach($array_contents as $key => $value){
        $result [$row][$key] = $value;
    }
}

var_dump($result);
?>

Here’s the output:

array(3) {
  [68]=>
  array(3) {
    [0]=>
    array(2) {
      ["id"]=>
      int(64)
      ["description"]=>
      string(19) "yada, yada, yada..."
    }
    [1]=>
    array(2) {
      ["id"]=>
      int(65)
      ["description"]=>
      string(20) "yada, yada, yada2..."
    }
    [2]=>
    array(2) {
      ["id"]=>
      int(66)
      ["description"]=>
      string(20) "yada, yada, yada3..."
    }
  }
  [69]=>
  array(3) {
    [0]=>
    array(2) {
      ["id"]=>
      int(64)
      ["description"]=>
      string(19) "yada, yada, yada..."
    }
    [1]=>
    array(2) {
      ["id"]=>
      int(65)
      ["description"]=>
      string(20) "yada, yada, yada2..."
    }
    [2]=>
    array(2) {
      ["id"]=>
      int(66)
      ["description"]=>
      string(20) "yada, yada, yada3..."
    }
  }
  [70]=>
  array(3) {
    [0]=>
    array(2) {
      ["id"]=>
      int(64)
      ["description"]=>
      string(19) "yada, yada, yada..."
    }
    [1]=>
    array(2) {
      ["id"]=>
      int(65)
      ["description"]=>
      string(20) "yada, yada, yada2..."
    }
    [2]=>
    array(2) {
      ["id"]=>
      int(66)
      ["description"]=>
      string(20) "yada, yada, yada3..."
    }
  }
}