PHP Add New Index to Multidimentional Array Without Notice - php

Question

Take this example:
$data = array();
$data['a']['one'] = 'test';
This will throw a notice because $data['a'] doesn't exist. So instead, I always do this:
$data = array();
$data['a'] = array();
$data['a']['one'] = 'test';
Or if I'm in a loop, something like this:
$data = array();
foreach ($items as $item) {
if (!isset($data['a'])) {
$data['a'] = array();
}
$data['a']['one'] = $item->getId();
}
This gets really reptitive in the code and messy. I know that I could write some kind of array_push alternative function to handle this, but I'm wondering if there is a way to do this with existing PHP methods.

Answer 1

Initialising the entire array (all keys, sub arrays etc) somewhere first is not practical.
This means remembering and maintaining it - when you have new data not previously accounted for, you have to also add it to the array initialisation.
(Urgh)
I would least delcare the var as an array ($data = array();) then you don't need is_array() - which is an annoying single line of code before you even do anything useful (two lines including the closing brace..).
However, your checking is not needed.
Your code checks if the array's sub array has been set, and if not you set it as an array and then set the data onto it.
This is not necessary, as you can set data in an array even if some of the sub keys/arrays had not previously been set.
For example this code (this is the entire file and all code ran) won't throw an error, warning, or notice:
$data['a']['one']['blah']['foo'] = 'test';
print_r($data);
echo $data['a']['one']['blah']['foo'];
The above outputs:
Array ([a] => Array ( [one] => Array ( [blah] => Array ( [foo] => test ) ) ) )
test
The above code will not return any warning/notice/errors.
Also notice I didn't even have $data = array().
(although you want to, as you likely use foreach and that initialisation negates the need for using is_array).
That was with error_reporting(-1);
TL;DR; - The Answer
So to answer your question, in your code you could do this (and receive no errors/notices/warnings):
$data = array();
// more data setting the array up
foreach ($items as $item) {
$data['a']['one'] = $item->getId();
}

Answer 2

You might wish to look into ArrayObject class, the following runs without errors or warnings
<?php
error_reporting(E_ALL| E_NOTICE);
ini_set('display_errors', 1);
$ar = new ArrayObject();
$ar['foo']['bar'] = 1;
assert($ar['foo']['bar'] === 1);
Checkout the ideone

Answer 3

Create the array during assignment:
$data=[];
$data['a'] = ['one' => 'test'];
Or create the whole structure in one go
$data = ['a'=>['one'=>'test']];

Answer 4

I dont believe there are any built in methods that suit your needs: PHP array functions
Maybe creating your own function would be the neatest way to achieve this. Or, depending on your use case you could create your array of data to add to key a separately like below:
$data = array();
$array_data = array();
foreach ($items as $key => $item) {
$array_data[$key] = $item->getId(); // presuming your 'one' is a dynamic key
}
$data['a'] = $array_data;
Whether or not this a better than your approach is a matter of opinion I suppose.

Answer 5

You can bypass notices by adding #. Also you can disable notices which I don't recommend at all.
I think there are better ways to write such codes:
$a['one'] = 'test';
$a['two'] = 'test';
$data['a'] = $a;
or:
$data['a'] = ['one'=>'test', 'two'=>'test']
or:
$data = ['a'=>['one'=>'test', 'two'=>'test']];

Answer 6

The methods that multiple people have suggested to simply create the array as a multidimensional array from the beginning is typically not an option when dealing with dynamic data. Example:
$orderItems = array();
foreach ($items as $item) {
$oId = $order->getId();
if (!isset($orderItems[$oId])) {
$orderItems[$oId] = array();
}
$pId = $item->getPackageNumber();
if (!isset($orderItems[$oId][$pId])) {
$orderItems[$oId][$pId] = array('packages'=>array());
}
$orderItems[$oId][$pId][] = $item;
}
It sounds like I need to create a function to do this for me. I created this recursive function which seems to do the job:
function array_md_push(&$array, $new) {
foreach ($new as $k => $v) {
if (!isset($array[$k])) {
$array[$k] = array();
}
if (!is_array($v)) {
array_push($array[$k], $v);
} else {
array_md_push($array[$k], $v);
}
}
}
$test = array();
$this->array_md_push($test, array('a' => array('one' => 'test')));
$this->array_md_push($test, array('a' => array('one' => 'test two')));
$this->array_md_push($test, array('a' => array('two' => 'test three')));
$this->array_md_push($test, array('b' => array('one' => 'test four')));
Which gives me this:
array(2) {
["a"] => array(2) {
["one"] => array(2) {
[0] => string(4) "test"
[1] => string(8) "test two"
}
["two"] => array(1) {
[0] => string(10) "test three"
}
}
["b"] => array(1) {
["one"] => array(1) {
[0] => string(9) "test four"
}
}
}

Answer 7

This works. You do not need to set as an empty array
$data['a']['one'] = 'test';