Function to replace only some values in multidimensional array in PHP

April 20, 2022

I have a base set of rules stored in an array as follows:

$base_settings = [
    'ruleset1' => [
        'rule1' => ['param1' => 50, 'param2' => 100],
        'rule2' => ['param1' => 6, 'param2' => 3, 'param3' => 2],
        'rule3' => ['param1' => 1500, 'param2' => 300, 'param3' => 100],
        'rule4' => 2
    ],
    'ruleset2' => 'date',
    'ruleset3' => [
        'param1' => ['string1', 'string2', 'string3', 'string4'],
        'param2' => ['string1', 'string2']
    ]
];

I also have a user-specific array which contains values that need to override the values in the array above. For example:

$priority_setting = [
    'ruleset1' => [
        'rule2' => ['param2' => 4, 'param3' => 6]
    ]
];

The $priority_settings array can be any ‘subset’ of the $base_settings array allowing the updating of many different rulesets. I am looking for a function that overrides the specific parts of the base array with those of the user-specific array, but without affecting the other elements. The result for the two arrays above should be:

$final_settings = [
    'ruleset1' => [
        'rule1' => ['param1' => 50, 'param2' => 100],
        'rule2' => ['param1' => 6, 'param2' => 4, 'param3' => 6],
        'rule3' => ['param1' => 1500, 'param2' => 300, 'param3' => 100],
        'rule4' => 2
    ],
    'ruleset2' => 'date',
    'ruleset3' => [
        'param1' => ['string1', 'string2', 'string3', 'string4'],
        'param2' => ['string1', 'string2']
    ]
];

The built-in PHP function, array_merge_recursive nearly does the trick, but adds rather than replaces. I am having problems with the fact that there are different depths to the rulesets leading to problems such as the $priority_settings array above ‘deleting’ param1 of rule 2, rather than just replacing param2 and param3 in the $final_settings array. Any help would be very much appreciated!

>Solution :

You are very close!

To add key/values into an array and replace key/values if they already exist you are looking for array_replace_recursive()

This function will recurse down the second parameter array, replacing any existing values, and adding any key/value pairs that do not exist.

$base_settings = [
    'ruleset1' => [
        'rule2' => ['param1' => 1, 'param2' => 2, 'param3' => 3],
    ],
];

$priority_setting = [
    'ruleset1' => [
        'rule2' => ['param2' => 420, 'param3' => 69]
    ]
];

//Update base settings with new values from priority settings
$base_settings = array_replace_recursive($base_settings, $priority_setting);

This results in the new $base_settings array:

Array(
    [ruleset1] => Array(
        [rule2] => Array(
            [param1] => 1
            [param2] => 420
            [param3] => 69
        )
    )
)