Combine two foreach loops for better inefficiency? - php

Question

I have the following code but I am wondering how I can make it more efficient.
if ($genres){
$arr = array();
foreach ($genres as $i) {
$arr[] = $i->name;
}
$genres_arr = $arr;
}
if ($themes){
$arr = array();
foreach ($themes as $i) {
$arr[] = $i->name;
}
$themes_arr = $arr;
}
var_dump($genres_arr);
var_dump($themes_arr);
I've tried putting them into an if statement but because they both always exists only the first one runs. I want to check to see if both exist and always run them both through a foreach loop. If only one exists I want only the one to run.
These are the array structures.
["genres"]=>
array(1) {
[0]=>
object(stdClass)#1579 (2) {
["id"]=>
int(25)
["name"]=>
string(26) "Hack and slash/Beat 'em up"
}
}
["themes"]=>
array(3) {
[0]=>
object(stdClass)#1576 (2) {
["id"]=>
int(1)
["name"]=>
string(6) "Action"
}
}
I want to have them as flattered as at the moment they are inside objects. I am then going to implode them into a list for WordPress use.
This code works but its repetitive and some help would be great!

Answer 1

I think you can use array column because it can read values from "A multi-dimensional array or an array of objects from which to pull a column of values from" like this:
if ($genres) {
$genres_arr = array_column($genres, 'name');
}
if ($themes) {
$themes_arr = array_column($themes, 'name');
}
var_dump($genres_arr);
var_dump($themes_arr);

Answer 2

In this way the easiest simplification would be to introduce a new function, which builds the array.
function getNames($arr) {
if (!is_array($arra)) return false;
return array_map(function($item) {
return $item->name;
}, $arr);
}
$themes_arr = getNames($themes);
$genre_arr = getNames($genres);

Answer 3

This is how I would combine them
$sets = [];
if ($genres){
$sets['genres'] = $genres;
}
if ($themes){
$sets['themes'] = $themes;
}
$arr = array();
foreach( $sets as $type => $data ){
foreach ($genres as $i) {
$arr[$type][] = $i->name;
}
}

Answer 4

claudio's answer is perfect for this situation, but in the more general case you can also define a mapping function, which you then use with array_map for both sets of objects, e.g.
$mapper = function ($item) { return $item->name; };
$genres_arr = array_map($mapper, $genres);
$themes_arr = array_map($mapper, $themes);
This has the advantage of being able to run more complex logic (using a getter function instead of direct property access, etc), if you need it in future.
Ideally, both objects would implement a common interface, so that it was clear exactly what kinds of objects the mapping function was designed for.