Given the following array and a given id, how can I return the corresponding elem? For instance, given id=6, it should return goodby. The id values are the PKs from a database, thus will always be unique.
Obviously, I could just iterate over the first array, check the values, and break and return the elem upon match, but I expect there is a much more elegant way to do this.
array(
array('id'=>2,'elem'=>"hello"),
array('id'=>6,'elem'=>"goodby"),
array('id'=>8,'elem'=>"goodnight")
);
A basic alternative to consider would be to collect the columns with array_column (indexed by the id column) and then dereferencing the array to access the passed index value $id, something like:
$myArray = array(
array('id'=>2,'elem'=>"hello"),
array('id'=>6,'elem'=>"goodby"),
array('id'=>8,'elem'=>"goodnight")
);
function getValue($id, $a)
{
return array_column($a, 'elem', 'id')[$id];
}
var_dump(getValue(6, $myArray));
Enhancing the proof to get more control:
function getValueAlternative($where, $get, $fromSource)
{
$where = explode("=", $where);
return array_column($fromSource, $get, $where[0])[$where[1]];
}
var_dump(getValueAlternative("id=2", "elem", $myArray));
var_dump(getValueAlternative("elem=hello", "id", $myArray));
See this :
myfunction($products, $needle)
{
foreach($products as $key => $product)
{
if ( $product['id'] === $needle )
return $key;
}
return false;
}
Similar : PHP Multidimensional Array Searching (Find key by specific value)
Why don't you use the following structure?:
array(
2 => array('elem'=>"hello", ...),
6 => array('elem'=>"goodby", ...),
8 => array('elem'=>"goodnight", ...)
);
Then you could access them like:
$array[$id];
You told that you've used PDOStatement::fetchAll() to obtain your array. You can tell fetchAll() to return a structure like I've suggested, you need to use the fetch mode PDO::FETCH_GROUP:
$pdo->query('SELECT * FROM table')->fetchAll(PDO::FETCH_GROUP);
Well defined data structures are the essential basics of a good program. In your case an associative array having the ids as their keys and the whole records as the value portion,will be better than a numeric array as it allows you to perform fast, id based access. Of course you have to pay for this - with a little more memory.
fetch().. fetchAll() makes no sense at all in the most cases.PDO::FETCH_GROUPYou could use the array_search PHP function:
/**
* @param array $array
* @param int $id
* @return string|null
*/
function getElem(array $array, $id) {
foreach($array as $subArr) {
if(($key = array_search($id, $subArr, true)) !== false) {
if(strcmp($key, "id") === 0) {
return $subArr['elem'];
}
}
}
return null;
}
$array = array(
array('id'=>2,'elem'=>"hello"),
array('id'=>6,'elem'=>"goodby"),
array('id'=>8,'elem'=>"goodnight")
);
echo getElem($array, 6);
