We need to define a filter interface and pass it here. Like the rule:

Add a command to create a filter.

Nah, it's not a good idea since the filter function can vary.

Maybe:

type Filter interface {
	// Signature set the unique signature of the filter.
	Signature() string
	// Passes determine if the validation rule passes.
	Handle() func(val any) (any, error)
}

Nah, it's not a good idea since the filter function can vary.

We can only support one style: func(val any) (any, error)

A developer can also create a filter function like this:

func Default(val string, def ...string) string {
    ...
}

which can be used like this:

map[string]string{
   "name" : "default:krishan"
}
// assume registered as "default"

So, let's not add constraints on developers since gookit/validate provides this feature.

Maybe:

type Filter interface {
	// Signature set the unique signature of the filter.
	Signature() string
	// Passes determine if the validation rule passes.
	Handle() func(val any) (any, error)
}

we can change it to ?

type Filter interface {
	// Signature set the unique signature of the filter.
	Signature() string
	// Passes determine if the validation rule passes.
	Handle() any // will mention in docs that any can only be two type of function
}

We also need to add a new Filter method in the FormRequest:

Users can use the Filter feature through the Filter method, instead of set a tag in the struct:

The way of set a tag in the struct is inconsistent with the rule, so I suggest optimize it. cc @devhaozi

So we need to fdmovd the logic in goravel/gin and goravel/fiber and add some new logic:

Great