Question

How to merge and overwrite multidimensional array with same key and value with array_merge_recursive ? Supposed I Have two array like below:

$arr1 = array(       
   // OVERWRITE
   array('prop_id' => 1, 'prop_value' => 'batman'),
   array('prop_id' => 2, 'prop_value' => 'ironman'),
   // NOT OVERWRITE
   array('prop_id' => 5, 'prop_value' => 'wonderwoman'),
);

$arr2 = array(
   array('prop_id' => 1, 'prop_value' => 'robin'),
   array('prop_id' => 2, 'prop_value' => 'superman'),
   array('prop_id' => 4, 'prop_value' => 'catwoman'),
);

I want to merge and overwrite it with new value (the rule is comparison key with the same value it not overwrite), the expected result is

 $result = array_merge_overwrite($arr1, $arr2, array('prop_id') /* Comparison Key */);
 $result = array(       
   array('prop_id' => 1 /* Comparison Key */, 'prop_value' => 'robin' /* Comparison value */),
   array('prop_id' => 2, 'prop_value' => 'superman'),
   array('prop_id' => 4, 'prop_value' => 'catwoman'),
   array('prop_id' => 5, 'prop_value' => 'wonderwoman'),
);

With array_merge_recursive it appended not overwrited, I try with array_replace_recursive like below:

$result = array_replace_recursive(
    array(
       1 => array('prop_id' => 1, 'prop_value' => 'batman'),
       2 => array('prop_id' => 2, 'prop_value' => 'ironman'),
       5 => array('prop_id' => 5, 'prop_value' => 'wonderwoman'),
    ),
    array(
       1 => array('prop_id' => 1, 'prop_value' => 'robin'),
       2 => array('prop_id' => 2, 'prop_value' => 'superman'),
       4 => array('prop_id' => 4, 'prop_value' => 'catwoman'),
    ),
);

It works, but my code look nasty and dirty. Any better solution than mine

Answer 1

Here is a function that would work as you described:

function array_merge_overwrite($arr1, $arr2, $uniques=array('prop_id'), $delimiter='-')
{
    $result = array();
    $uk = array();
    foreach($arr1 as $a1)
    {   
        $uk = array();
        foreach($uniques as $u) $uk[] = $a1[$u];
        $result[implode($delimiter, $uk)] = $a1;
    }   

    foreach($arr2 as $a2)
    {   
        $uk = array();
        foreach($uniques as $u) $uk[] = $a2[$u];
        $result[implode($delimiter, $uk)] = $a2;
    }   
    return $result;
}

If passed $arr1 and $arr2 as defined in the question, the above function will return an array:

Array
(
    [1] => Array
        (
            [prop_id] => 1
            [prop_value] => robin
        )

    [2] => Array
        (
            [prop_id] => 2
            [prop_value] => superman
        )

    [5] => Array
        (
            [prop_id] => 5
            [prop_value] => wonderwoman
        )

    [4] => Array
        (
            [prop_id] => 4
            [prop_value] => catwoman
        )

)

Of course, if you were to always and only use prop_id as the unique element then the function could be quite a bit simpler:

function array_merge_overwrite($arr1, $arr2)
{
    $tmp = array();
    foreach($arr1 as $a1) $tmp[$a1['prop_id']] = $a1['prop_value'];
    foreach($arr2 as $a2) $tmp[$a2['prop_id']] = $a2['prop_value'];
    $result = array();
    foreach($tmp as $k=>$v) $result[] = array('prop_id'=>$k, 'prop_value'=>$v);
    return $result;
}

The only difference in the returned array in this later function is that the keys of the element arrays will be the standard numerical values instead of matching the prop_ids