[5.7] Add new conditional rule for validation

[krve]

This PR adds a new conditional rule that allows conditionally adding rules based on a closure or boolean.

Example

$this->validate($data, [
    'user_id' => [
        'numeric',
        Rule::conditional(Auth::user()->isAdmin())->passes(['required', 'numeric'])->fails('nullable'),
    ],
]);

This also allows complex nested rules if you want. (These can be nested as far as you need - even with a conditional rule inside a conditional rule)

$this->validate($data, [
    'user_id' => [
        'numeric',
        Rule::conditional(Auth::user()->isAdmin())->passes(new MyCustomRule),
    ],
]);

This would also replace some of the usage of $v->sometimes.

Sometimes approach:

$v->sometimes('reason', 'required|max:500', function ($input) {
    return $input->games >= 100;
});

Conditional Rule approach:

$this->validate($input, [
    'reason' => Rule::conditional($input->games >= 100)->passes('required', 'max:500'),
]);

This to me is a much simpler way of doing conditional validation and looks alot cleaner too.

[garygreen]

What's the benefit of doing:

$this->validate($data, [
    'user_id' => [
        'numeric',
        Rule::conditional(Auth::user()->isAdmin())->passes('required')->fails('nullable'),
    ],
]);

vs

$this->validate($data, [
    'user_id' => [
        'numeric',
        Auth::user()->isAdmin() ? 'required' : 'nullable',
    ],
]);

To me the latter is more readable.

Why must we have a wrapper around every little thing like this? Just branch code as and when you need to.

[krve]

In your example there is no benefit. But as soon as you need more than 1 rule to be merged in, you are going to run into trouble.

$this->validate($data, [
    'user_id' => [
        'numeric',
        Rule::conditional(Auth::user()->isAdmin())
            ->passes('required', Rule::exists('users', 'id'))
            ->fails('nullable'),
    ],
]);

Without the conditional rule, this would not be possible without merging the entire array of rules conditionally.

Just branch code as and when you need to.

I have something similar to this in my own project, but I cannot use it in the same way because of the way the Laravel Validator parses rules. So instead I have to do as stated above - conditionally merge the rules-array - which quickly becomes a huge burden to maintain.

[garygreen]

Instead of:

$this->validate($data, [
    'user_id' => [
        'numeric',
        Rule::conditional(Auth::user()->isAdmin())
            ->passes('required', Rule::exists('users', 'id'))
            ->fails('nullable'),
    ],
]);

I would write:

$this->validate($data, [
    'user_id' => collect([
        'numeric',
        Auth::user()->isAdmin() ? ['required', Rule::exists('users', 'id')] : 'nullable'
    ])->flatten()
]);

The conditional wrapper might add a bit of syntax sugar but imo it's not as readable and adds Yet Another Wrapper™. I try to avoid "clever code" like this and just keep things simple. Meh.

[krve]

I see your point and yes the code you wrote is simple and readable, but I still think this is more readable to me - especially without the need to wrap the rules in a collection and then flatten them.

What about renaming some of the methods to be more readable? Something like Rule::if()

[garygreen]

But why? This PR is essentially just flattening the rules in the same sort of way. If you want that kind of syntax sugar, maybe a package would be better - all you need to do is flatten the rules.

You could just add a helper method which calls collect(..)->flatten()

$this->validate($data, [
    'user_id' => conditionalRules([
        'numeric',
        Auth::user()->isAdmin() ? ['required', Rule::exists('users', 'id')] : 'nullable'
    ])
]);

I would prefer to see a PR that adds a flatten rule that will flatten all the rules before processing, IMO.

$this->validate($data, [
    'user_id' => [
        'flatten',
        'numeric',
        Auth::user()->isAdmin() ? ['required', Rule::exists('users', 'id')] : 'nullable'
    ]
]);

But it's not really needed. This is kind of an edge case.

[krve]

Thanks for the discussion. After giving it some thought I think I will make it a package instead. I never really liked the way it works right now, because it always has to loop through every rule to check if a conditional rule exist.

The whole collect(..)->flatten() gave me an idea on how to handle the conditional rules in my package - so thanks! 👍