Improve type safety of Request input methods

[supun-io]

This discussion is about the following methods implemented in InteractsWithInput for Request class.

• str()
• string()
• boolean()
• integer()
• float()
• enum()
• date()

Suggestion 1: A way to get a string, not Stringable

Both string() and str() methods return a Stringable object, not a string. Therefore, we have to always cast it to a string in our code, which is repetitive.

$name = (string) $request->string('name');

The problem with Stringable is when you use strict types in PHP. Most (almost all) dependencies are typed to take strings as parameters, never Stringable.

<?php declare(strict_types=1);

$name = $request->string('name');
SomeLibrary::process($name); // <- this throws an type error when the dependency uses strict types

For that reason, my first suggestion is that there should be a way to get a string directly from the request. However, I am not sure what the best way to implement this.

• Change string() method (backward incompatible and risky)
• Add a new method like stringRaw()

Suggestion 2: Null inconsistency

enum() and date() methods can return null values. For this reason, these functions are almost not useful when writing strictly type-safe code.

$type = $request->enum('type', TypeEnum::class); // TypeEnum|null
SomeLibrary::process($type); // this shows a static error because `enum()` cannot guarantee a non-null value

Therefore we have to always do this, which is verbose.

$type = TypeEnum::from((string) $request->string('type'));
SomeLibrary::process($type); // no static errors

The ideal solution would be throw an exception on invalid enums in enum() method. Currently, it uses ::tryFrom - it could be changed to ::from().

But, again, this will be backward incompatible.

Suggestion 3: A new nullable method

Sometimes, you need to get inputs that may be null. Currently, here's how you would do that (there could be a less complicated way).

$nullableInt = $request->input('limit');
$nullableInt = $nullableInt === null ? null : (int) $nullableInt;

My suggestion is:

$nullableInt = $request->nullable()->integer('limit');

#1 and #2 suggestions needs to be discussed because of the backward compatibility issues. #3 can be easily implemented (though it won't make sense with enum() and date()). I'm happy to work on a PR for #3.