Say I have a data structure like this:
array(3) {
["id"]=>
int(1)
["name"]=>
string(3) "foo"
["message"]=>
array(1) {
["action"]=>
string(3) "PUT"
}
}
Where 'message' and 'action' are both optional. To check if they're present my first attempt would be to write something like this:
if (array_key_exists('message', $array) && array_key_exists('action', $array['message'])){
}
Is there a cleaner implementation?
No, this is just the way of doing it.
Even when I'm not limited to a certain script language, I can't think of an cleaner solution?
You can just do this!
if (isset($array["message"]["action"])) { /*...*/ }
Proof:
<?php
error_reporting(E_ALL);
ini_set('error_reporting', E_ALL);
ini_set('display_errors', 1);
$array = [
"id" => 1,
"name" => "foo",
"message" => [
"action" => "PUT",
],
];
var_dump(isset($array["message"]["action"])); // true
$array = [
"id" => 1,
"name" => "foo"
];
var_dump(isset($array["message"]["action"])); // false
No log entries.
Do note that if your value is null, then isset will also return false. You probably shouldn't be creating values with null.
) and may cause a log entry to be generated due to not checking isset($array['message']) before dereferencing it.
\$\endgroup\$
– Brythan
Nov 1 '14 at 23:13
).
\$\endgroup\$
– CMCDragonkai
Nov 2 '14 at 5:10
Not clearer but probably the fastest solution:
if ((isset($array["message"]["action"]) ||
(array_key_exists('message', $array) && array_key_exists('action', $array['message']))) {
/* ... */
}
The second check is needed because some values evaluated with isset() will result false despite the index does exist.
I'm using this in a project of mine, but I'm using null as a muted state. (php 5.6)
<?php
function &option_select($options, $default, ...$path) {
if(!isset($path[0])) { return $options; }
$cursor = &$options;
foreach($path as $key) {
if(isset($cursor[$key])) { $cursor = &$cursor[$key]; } else { return $default; }
} return $cursor;
}
It's a function that will lookup a path in a tree.
echo option_select([A=>[B=>[C=>'hello world']]], 'NO?', 'A', 'B', 'C');
As you can see. I'm looping over the values over a array: path. In the beginning I'm setting a cursor as reference to a array I have to search in. Every time I find a new key, I'm setting the reference of the cursor to the current key I'm searching for. If you have xdebug and a good GUI, you can rewrite it to the algorithm you want. It's the isset($cursor[$key]) you have to change. Or inject it as a function: f($cursor, $key, $default) => (bool)
Been looking for a similar solution myself and came up with this. Works to determine if the key is set at all - and will return TRUE even if the value of the "action" key is NULL.
if (isset($array['message']) && array_key_exists('action',$array['message'])) {
/* ... */
}
If $array['message'] has no keys, the isset will return FALSE stopping the IF statement. If $array['message'] has any keys - even ones with NULL values - isset will return TRUE, allowing you to safely check if the 'action' array key exists in $array['message'].
