I want to get a value from the session, but use a default if it is not defined. And ofcourse I want to circumvent the PHP notice.
You can write a function that does this
function get(&$var, $default){
if(isset($var)) return $var;
return $default;
}
echo get($foo, "bar\n");
$foobar = "foobar";
echo get($foobar, "ERROR");
Is there a way to do this without defining this function in every file?
You can define it in one script and then require_once that script in your other scripts
You could also just use the ternary operator:
$myVar = isset($var)?$var:$default;
From PHP 7, you can now use the null coalescing operator :
$var ?? $default
that does exactly like your function
Use this concise alternative:
isset($myVar) || $myvar=$default;
The || operator is short circuit, it will not evaluate second operant if the first one be evaluated true.
The Null coalescing operator has been added to PHP version 7.0, what it does is replaces
$username = isset($_GET['user']) ? $_GET['user'] : 'nobody';
with a shorter version:
$username = $_GET['user'] ?? 'nobody';
What the line above does, is check if $_GET['user'] is set, and not null, then it will assign that to the $username variable, if $_GET['user'] is not set (and thus null) it will default to the 'nobody' string so $username is nobody.
Your code should look like:
echo $foo ?? "bar\n";
$foobar = "foobar";
echo $foobar ?? "ERROR";
Use less code to do what you need.
You don't need to specify the variable again using the _?_:_ format.
echo $var?:"default";
Is the same as
echo $var?$var:"default";
Now as far as an empty check, you could use @ to mute notices, I'm not sure of the technical ramifications, but you're already doing your own checking while using this format:
echo @$non_existing_var?:"default";
Some examples:
<?php
$nope = null;
$yup = "hello";
echo ($nope?:$yup) . "\n" ;
echo ($yup?:$nope) . "\n" ;
$items = [ 'one', 'two', false, 'three', 'four', null ];
foreach($items as $item):
echo($item?:"default shown (".var_export($item,true).")")."\n";
endforeach;
echo(@$non_existing?:"default for non-existant variable!");
?>
Output:
$ php variabledefault.php
hello
hello
one
two
default shown (false)
three
four
default shown (NULL)
default for non-existant variable!%
$v=false; echo $v?:"not set"; will incorrectly yield "not set"false"
print @$_SESSION['derp']?:"default"; That said, yes, if it's false, it will return the default, but that's how logic works.You could use my tiny library ValueResolver in this case, for example:
$myVar = ValueResolver::resolve($var, $default);
and don't forget to use namespace use LapaLabs\ValueResolver\Resolver\ValueResolver;
There are also ability to typecasting, for example if your variable's value should be integer, so use this:
$id = ValueResolver::toInteger('6 apples', 1); // returns 6
$id = ValueResolver::toInteger('There are no apples', 1); // returns 1 (used default value)
Check the docs for more examples
