Get array value based on variable and indexes as string - php

Question

I'm trying to execute variable which part of it is a string.
Here it is:
$row = array(
'index_1' => array(
'index_2' => 'my-value'
)
);
$pattern = "['index_1']['index_2']";
I tried to do it in following ways:
// #1
$myValue = $row{$pattern};
// #2
$myValue = eval("$row$pattern");
I also trying to get it working with variable variable, but not successful.
Any tips, how should I did it? Or myabe there is other way. I don't know how may look array, but I have only name of key indexes (provided by user), this is: index_1, index_2

Answer 1

You could use eval but that would be quite risky since you say the values come from user input. In that case, the best way might be to parse the string and extract the keys. Something like this should work:
$pattern = "['index_1']['index_2']";
preg_match('/\[\'(.*)\'\]\[\'(.*)\'\]/', $pattern, $matches);
if (count($matches) === 3) {
$v = $row[$matches[1]][$matches[2]];
var_dump($v);
} else {
echo 'Not found';
}

Answer 2

This can help -
$row = array(
'index_1' => array(
'index_2' => 'my-value'
)
);
$pattern = "['index_1']['index_2']";
$pattern = explode("']['", $pattern); // extract the keys
foreach($pattern as $key) {
$key = str_replace(array("['", "']"), '', $key); // remove []s
if (isset($row[$key])) { // check if exists
$row = $row[$key]; // store the value
}
}
var_dump($row);
Storing the $row in temporary variable required if used further.
Output
string(8) "my-value"

Answer 3

If you always receive two indexes then the solution is quite straight forward,
$index_1 = 'index_1';// set user input for index 1 here
$index_2 = 'index_2';// set user input for index 2 here
if (isset($row[$index_1][$index_2])) {
$myValue = $row[$index_1][$index_2];
} else {
// you can handle indexes that don't exist here....
}
If the submitted indexes aren't always a pair then it will be possible but I will need to update my answer.

Answer 4

As eval is not safe, only when you know what you are ding.
$myValue = eval("$row$pattern"); will assign the value you want to $myValue, you can add use return to make eval return the value you want.
here is the code that use eval, use it in caution.
demo here.
<?php
$row = array(
'index_1' => array(
'index_2' => 'my-value'
)
);
$pattern = 'return $row[\'index_1\'][\'index_2\'];';
$myValue = eval($pattern);
echo $myValue;