PHP - Get key from another key value through a multi dimensional array - php

Question

I have the following multidimensional array that is obtained through an API.
$exchangeID = array(
0 => array(
'id' => 'vcxz',
'currency' => 'GBP',
),
1 => array(
'id' => 'mnbv',
'currency' => 'EUR',
),
2 => array(
'id' => 'lkjh',
'currency' => 'USD',
),
3 => array(
'id' => 'poiuy',
'currency' => 'KRN',
),
);
I would like to obtain the id of USD which is lkjh. I know this can be obtained by simply doing $exchangeID[2]['id']. The problem is that the array is dynamic. For example when it is loaded the first subarray may be EUR instead of GBP, and the third subarray may be KRN instead of USD.
Basically, what I have in mind is to look for the subarray where there is the currency first, then accordingly find the corresponding id. E.g. if I want to find EUR. First I find the EUR, then get 'mnbv'.
I tried this $key = array_search('USD', array_column($exchangeID, 'currency')); but I got the following error in my error_log PHP Fatal error: Call to undefined function array_column() to get at least the array number e.g. in this case 2.

Answer 1

You can simply filter your array, like this:
$usd_exchanges = array_filter($exchangeID, function($row) {
return $row['currency'] == "USD";
}));
var_dump($usd_exchanges[0]);
You can also return the first element of the filter, using the current method:
$usd_exchange = current(array_filter($exchangeID, function($row) {
return $row['currency'] == "USD";
})));
var_dump($usd_exchange);

Answer 2

Try this:
foreach ($exchangeID as $key => $arr)
if($arr['currency'] == 'USD')
echo $key;
It is possible to use following custom function to get the key:
echo getKeyRecursive('USD', $exchangeID);
function getKeyRecursive($needle, $haystack, $strict = false)
{
foreach ($haystack as $key => $item){
if(($strict ? $item === $needle : $item == $needle) || (is_array($item) && getKeyRecursive($needle, $item, $strict))) return $key;
}
return false;
}

Answer 3

foreach($exchangeID as $key=>$value)
{
if($exchangeID[$key]['currency']=='USD'){
$usdId=$exchangeID[$key]['id'];
break;
}
}
//echo $usdId;
//Result:ikjh

Answer 4

<?php
$exchangeID = array(
0 => array(
'id' => 'vcxz',
'currency' => 'GBP',
),
1 => array(
'id' => 'mnbv',
'currency' => 'EUR',
),
2 => array(
'id' => 'lkjh',
'currency' => 'USD',
),
3 => array(
'id' => 'poiuy',
'currency' => 'KRN',
),
);
$db=new PDO('sqlite::memory:','','',array(PDO::ATTR_EMULATE_PREPARES => false, PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
$db->query('CREATE TABLE `troll` (`dbid` TEXT, `dbcurrency` TEXT);');
$stm=$db->prepare("INSERT INTO `troll` (`dbid`,`dbcurrency`) VALUES(:id,:currency);");
array_walk($exchangeID,function($arr)use($stm){$stm->execute($arr);});
$res=$db->query("SELECT `dbid` AS `id` FROM `troll` WHERE `dbcurrency` = ".$db->quote('USD').' LIMIT 1');
$id=$res->fetch(PDO::FETCH_ASSOC);
$id=$id['id'];
var_dump($id);
see working example here http://codepad.viper-7.com/1lg2Gj

Answer 5

Try this if this works:
foreach($exchangeID as $key => $val)
{
if(array_key_exists('currency', $val))
if($val['currency'] == 'USD'){
echo $val['id'];
echo $val['currency'];
elseif($val['currency'] == 'GBP'){a1
echo $val['id'];
echo $val['currency']);
elseif($val['currency'] == 'EUR'){
echo $val['id'];
echo $val['currency'];
}else{
echo $val['id'];
echo $val['currency'];
}
}
}