I have basic enum
enum Fruit
{
case APPLE;
case ORANGE;
case BANANA;
}
and some function that uses typing with that enum:
function eatFruit (Fruit $fruit)
{
// do stuff
}
and variable with unknown content
$fruit = $_POST['fruit']; // user choosed "MILK"
if (?????) { // how to check if it's fruit?
eatFruit($fruit); // this should not be executed
}
I cannot find in documentation simple way to check if enum contains specific case.
It is possible with backed enums like that
enum Fruit
{
case APPLE = 'APPLE';
case ORANGE = 'ORANGE';
case BANANA = 'BANANA';
}
Fruit::from('');
Fruit::tryFrom('');
This will work, but from
does not exist on non-backed enums form my first example.
Fatal error: Uncaught Error: Call to undefined method Fruit::from()
You can use the static method cases()
for this. This returns an array of all values in the enum. The values have a "name" property that is a string representation you can check against (backed enums also have a "value" property that contains the string value you defined in the enum).
So an example implementation could be something like:
enum Fruit {
case APPLE;
case ORANGE;
case BANANA;
}
// String from user input
$fruit = $_POST['fruit'];
// Find matching fruit in all enum cases
$fruits = Fruit::cases();
$matchingFruitIndex = array_search($fruit, array_column($fruits, "name"));
// If found, eat it
if ($matchingFruitIndex !== false) {
$matchingFruit = $fruits[$matchingFruitIndex];
eatFruit($matchingFruit);
} else {
echo $fruit . " is not a valid Fruit";
}
function eatFruit(Fruit $fruit): void {
if ($fruit === Fruit::APPLE) {
echo "An apple a day keeps the doctor away";
} elseif ($fruit === Fruit::ORANGE) {
echo "When life gives you oranges, make orange juice";
} elseif ($fruit === Fruit::BANANA) {
echo "Banana for scale";
}
}
Working version with sample data: https://3v4l.org/ObD3s
If you want to do this more often with different enums, you could write a helper function for this:
function getEnumValue($value, $enumClass) {
$cases = $enumClass::cases();
$index = array_search($value, array_column($cases, "name"));
if ($index !== false) {
return $cases[$index];
}
return null;
}
$fruit = getEnumValue($_POST['fruit'], Fruit::class);
if ($fruit !== null) {
eatFruit($fruit);
} else {
echo $_POST['fruit'] . " is not a valid Fruit";
}
Example with the same sample data: https://3v4l.org/bL8Wa