aaronrussell aaronrussell - 25 days ago 6x
PHP Question

How to convert all keys in a multi-dimenional array to snake_case?

I am trying to convert the keys of a multi-dimensional array from CamelCase to snake_case, with the added complication that some keys have an exclamation mark that I'd like removed.

For example:

$array = array(
'!AccountNumber' => '00000000',
'Address' => array(
'!Line1' => '10 High Street',
'!line2' => 'London'));

I would like to convert to:

$array = array(
'account_number' => '00000000',
'address' => array(
'line1' => '10 High Street',
'line2' => 'London'));

My real-life array is huge and goes many levels deep. Any help with how to approach this is much appreciated!


This is the modified function I have used, taken from soulmerge's response:

function transformKeys(&$array)
  foreach (array_keys($array) as $key):
    # Working with references here to avoid copying the value,
    # since you said your data is quite large.
    $value = &$array[$key];
    # This is what you actually want to do with your keys:
    #  - remove exclamation marks at the front
    #  - camelCase to snake_case
    $transformedKey = strtolower(preg_replace('/([a-z])([A-Z])/', '$1_$2', ltrim($key, '!')));
    # Work recursively
    if (is_array($value)) transformKeys($value);
    # Store with new key
    $array[$transformedKey] = $value;      
    # Do not forget to unset references!