Get a value from a multidimensional array using the dot syntax

Question

I have the following array:

$conf = array(
'db'    => array(
    'server'    =>  'localhost',
    'user'      =>  'root',
    'pass'      =>  'root',
    'name'      =>  'db',
    ),
'path'  =>  array(
    'site_url'  =>  $_SERVER['SERVER_NAME'],
    'site_dir'  => CMS,
    'admin_url' => conf('path.site_url') . '/admin',
    'admin_dir' => conf('path.site_dir') . DS .'admin',
    'admin_paths' => array(
                'assets' => 'path'
                ),
    ),
);

I would like to get a value from this array using a function like so:

/**
 * Return or set a configuration setting from the array.
 * @example
 * conf('db.server')    => $conf['db']['server']
 *
 * @param  string $section the section to return the setting from.
 * @param  string $setting the setting name to return.
 * @return mixed           the value of the setting returned.
 */
function conf($path, $value = null) {
    global $conf;
    // We split each word seperated by a dot character
    $paths = explode('.', $path);

    return $conf[$paths[0]][$paths[1]];
}

But i would like it if the function resolves all dimensions of the array and not just the first two.

Like this

conf('path.admin_paths.assets');

would resolve to

=> $conf['path']['admin_paths']['assets']

How would i do this? Also, how would i make this function if it has another param, would set a value rather than return it?

gabrieloliveira · Answer 1 · 2014-03-24T19:35:14.537

This function works:

function conf($path, $value = null) {
    global $conf;
    // We split each word seperated by a dot character
    $paths = explode('.', $path);
    $result = $conf;
    foreach ($paths as $path) {
        $result = $result[$path];
    }
    return $result;
}

Edit:

Add Set:

function conf($path, $value = null) {
    global $conf;
    // We split each word seperated by a dot character
    $paths = explode('.', $path);
    if ($value === null) {
        // Get
        $result = $conf;
        foreach ($paths as $path) {
            $result = $result[$path];
        }
        return $result;
    }
    // Set
    if (!isset($conf)) $conf = array(); // Initialize array if $conf not set
    $result = &$conf;
    foreach ($paths as $i=>$path) {
        if ($i < count($paths)-1) {
            if (!isset($result[$path])) {
                $result[$path] = array();
            }
            $result = &$result[$path];
        } else {
            $result[$path] = $value;
        }
    }
}

This is to get a value. Where is the set? – Xees Mar 24 '14 at 19:24 — Xees, Mar 24 '14 at 19:24

score 3 · Accepted Answer · answered Mar 24 '14 at 18:29

I found @Danijel recursive approach a lot cleaner than my initial try. So here's a recursive implementation of the functionality, supporting setting values.

function array_get_by_key(&$array, $key, $value = null) {
    list($index, $key) = explode('.', $key, 2);
    if (!isset($array[$index])) throw new Exception("No such key: " . $index);

    if(strlen($key) > 0)
        return array_get_by_key(&$array[$index], $key, $value);

    $old = $array[$index];
    if ($value !== null) $array[$index] = $value;
    return $old;    
}

function config($key, $value = null) {
    global $CONFIG;
    return array_get_by_key(&$CONFIG, $key, $value);
}

Test run:

$CONFIG = array(
'db'    => array(
    'server'    =>  'localhost',
    'user'      =>  'root',
    'pass'      =>  'root',
    'name'      =>  'db',
    ),
'path'  =>  array(
    'site_url'  =>  'localhost',
    'site_dir'  => 'CMS',
    'admin_url' => 'localhost/admin',
    'admin_dir' => 'localhost/res/admin',
    'admin_paths' => array(
                'assets' => 'path'
                ),
    ),
);

try {
    var_dump(config('db.pass'));
    var_dump(config('path.admin_url', 'localhost/master'));
    var_dump(config('path.admin_url'));
    var_dump(config('path.no_such'));
} catch (Exception $e) {
    echo "Error: trying to access unknown config";
}

// string(4) "root"
// string(15) "localhost/admin"
// string(16) "localhost/master"
// Error: trying to access unknown config

Pierre Granger · Answer 3 · 2014-03-24T17:11:10.270

2

function conf($path,$value=null) {
    global $conf;
    // We split each word seperated by a dot character
    $paths = explode('.', $path);
    $temp = $conf ;
    $ref = &$conf ;
    foreach ( $paths as $p )
    {
        $ref = &$ref[$p] ; // Register the reference to be able to modify $conf var
        if ( isset($temp[$p]) )
            $temp = $temp[$p] ;
        elseif ( $value !== null ) // This key does not exist, and we have a value : time to modify
            $ref = $value ;
        else // Key does not exist and no value to add
            return false ;
    }
    return $temp ;
}

edited Mar 24 '14 at 17:11

answered Mar 24 '14 at 16:20

Pierre Granger

1,993
2
15
21

But, how would i use this function to also set values to the global config array. See my edit above. – Xees Mar 24 '14 at 16:42
I updated with help of swordofpain reference trick, it should do the stuff. – Pierre Granger Mar 24 '14 at 17:12

score 2 · Answer 4 · edited May 23 '17 at 12:24

function conf($path, $value = null) {
    global $conf;
    $paths = explode('.', $path);

    $array = &$conf; // Reference to the config array

    foreach ($paths as $k) {
        if (!is_array($array)) throw new Exception("No such key: " . $path);
        if (!isset($array[$k])) throw new Exception("No such key: " . $path);

        // In order to walk down the array, we need to first save the ref in
        // $array to $tmp
        $tmp = &$array;
        // Deletes the ref from $array
        unset($array);
        // Create a new ref to the next item
        $array =& $tmp[$k];
        // Delete the save
        unset($tmp);
    }

    $val = $array

    if ($value !== null) $array = $value;

    return $array
}

(Code inpired by this SO question and Pierre Granger's answer)

Gives an Fatal error: Uncaught exception 'Exception' with message '0' — Xees, Mar 24 '14 at 16:57
throw new Exception("No such key: " . $path); Try a dot instead of the + — Pierre Granger, Mar 24 '14 at 17:02

Danijel · Answer 5 · 2014-03-24T18:52:03.857

As I see it, to get any value from the multidimensional array, recursion is the proper way. Also, you can't use conf() function inside the $conf array before the array is initialized ( the global $conf; will be NULL, eg. not set )

function conf( $path ) {
    global $conf;
    return recurse( $conf, explode( '.', $path ) );
}

function recurse( $array, $keys ) {

    if ( isset( $keys[0] ) && isset( $array[$keys[0]] ) ) {

        $array = $array[$keys[0]];
        array_shift( $keys );
        return recurse( $array, $keys );

    } else return is_string( $array ) ? $array : false ;

}


print_r2( conf('path.admin_paths.assets') );    // @str  "path"
print_r2( conf('path.admin_paths') );           // @bool false ( path is invalid )
print_r2( conf('path.admin_url') );             // @str  "/admin" 
print_r2( conf('db.server') );                  // @str  "localhost"

How can i use the conf, function inside the array? I want the array to use other parts of the array itself. — Xees, Mar 24 '14 at 19:27

score 1 · Answer 6 · answered Nov 11 '16 at 14:46

I have implemented array access class CompositeKeyArray, that hides away the recursion so you can simply get and set nested keys.

Given that class the original problem can be solved like this:

$conf = new CompositeKeyArray($conf);

var_dump($conf[['path', 'admin_paths', 'assets']]); // => string(4) "path"

If you want you can change the value:

$conf[['path', 'admin_paths', 'assets']] = 'new path';

var_dump($conf[['path', 'admin_paths', 'assets']]); // => string(8) "new path"

Or even unset it:

unset($conf[['path', 'admin_paths', 'assets']]);

var_dump(isset($conf[['path', 'admin_paths', 'assets']])); // => bool(false)

Here is working demo.

Get a value from a multidimensional array using the dot syntax

6 Answers6

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