Coalesce isn't really the right word as it returns the first non-NULL value, but hopefully it conveys the intent.
Is there a more-readable and concise way to do get the first defined value of foo from $arr, $_GET, and then $_POST?
function foo($arr=array())
{
$arr['bar']=isset($arr['bar'])?$arr['bar']:(isset($_GET['bar'])?$_GET['bar']:(isset($_POST['bar'])?$_POST['bar']:NULL));
// ....
}
array_merge is the function you're looking for. Precedence given to the last parametric array.
$allData = array_merge($_POST, $_GET, $arr);
return $allData['bar'];
There are a few answers here that could work, although none are great to look at: Using short circuiting to get first non-null variable
Chosen answer from above modified for your variables:
@$arr['bar'] = $arr['bar'] ?: $_GET['bar'] ?: $_POST['bar'] ?: NULL;
There are a couple issues with using array_merge or the + operator with arrays assuming there is a defined offset but the value happens to be null.
Here are three different approaches and the output from each.
<?php
$a = ['foo' => null];
$b = ['foo' => 'bar_b'];
$c = ['foo' => 'bar_c'];
var_dump($a + $b + $c);
var_dump(array_merge($c, $b, $a)); //reverse order here!
function getFirstSetOffsetFromArrays($key, $arr) {
foreach($arr as $v) {
if (isset($v[$key]) && !empty($v[$key])) {
return $v[$key];
}
}
}
var_dump(getFirstSetOffsetFromArrays('foo', [$a, $b, $c]));
Output:
array(1) { ["foo"]=> NULL }
array(1) { ["foo"]=> NULL }
string(5) "bar_b"
There are several good examples here already, but I'd prefer to:
$arr['bar'] =
current(filter_var_array($arr, ['bar' => FILTER_DEFAULT])) ?:
filter_input(INPUT_GET, 'bar', FILTER_DEFAULT) ?:
filter_input(INPUT_POST, 'bar', FILTER_DEFAULT) ?:
null;
@.$_GET and $_POST are used, otherwise too complicated.