get-in

Functions for hash map (assoc array) traversal.

When dealing with nested associative structures, traversing them can become quite a pain. Mostly because of the amount of isset checking that is necessary.

For example, to access a nested key ['foo']['bar']['baz'], you must do something like this:

$baz = (isset($data['foo']['bar']['baz'])) ? $data['foo']['bar']['baz'] : null;

Enough already! get-in provides a better way:

$baz = igorw\get_in($data, ['foo', 'bar', 'baz']);

Installation

Through composer:

$ composer require igorw/get-in:~1.0

Usage

get_in

Retrieve value from a nested structure using a list of keys:

$users = [
    ['name' => 'Igor Wiedler'],
    ['name' => 'Jane Doe'],
    ['name' => 'Acme Inc'],
];

$name = igorw\get_in($users, [1, 'name']);
//= 'Jane Doe'

Non existent keys return null:

$data = ['foo' => 'bar'];

$baz = igorw\get_in($data, ['baz']);
//= null

You can provide a default value that will be used instead of null:

$data = ['foo' => 'bar'];

$baz = igorw\get_in($data, ['baz'], 'qux');
//= 'qux'

update_in

Apply a function to the value at a particular location in a nested structure:

$data = ['foo' => ['answer' => 42]];
$inc = function ($x) {
    return $x + 1;
};

$new = igorw\update_in($data, ['foo', 'answer'], $inc);
//= ['foo' => ['answer' => 43]]

You can variadically provide additional arguments for the function:

$data = ['foo' => 'bar'];
$concat = function (/* $args... */) {
    return implode('', func_get_args());
};

$new = igorw\update_in($data, ['foo'], $concat, ' is the ', 'best');
//= ['foo' => 'bar is the best']

assoc_in

Set a value at a particular location:

$data = ['foo' => 'bar'];

$new = igorw\assoc_in($data, ['foo'], 'baz');
//= ['foo' => 'baz']

It will also set the value if it does not exist yet:

$data = [];

$new = igorw\assoc_in($data, ['foo', 'bar'], 'baz');
//= ['foo' => ['bar' => 'baz']]

Inspiration

The naming and implementation is inspired by the get-in, update-in and assoc-in functions from clojure.