Allow passing validation rule parameters to the error message bag

[nhedger]

Idea

Allowing the validator to optionally return the validation rule parameters within the error message bag.

Use case

In a multilingual SPA, this would allow us to return the error from Laravel as a translation key while retaining access to the rule parameters, enabling us to reconstruct the error message on the frontend. That way, you only have to manage one set of translation files.

Example

Given the following validator

$validator = Validator::make($request->all(), [
    'name' => 'min:5',
], [
    'name.min' => 'my.translation.key',
]);

We'd currently get the following JSON

{
  "name": [
    "my.translation.key"
  ]
}

By passing the rule parameters we'd get the following JSON instead

{
  "name": [
    {
      "message": "my.translation.key",
      "parameters": [
        "5"
      ]
    }
  ]
}

Implementation

I am willing to implement this feature and send a PR.

I've already done some preliminary work to test my idea and it would most likely consist of modifying the following lines.

framework/src/Illuminate/Validation/Validator.php

Lines 822 to 824 in 7920ca5

	$this->messages->add($attribute, $this->makeReplacements(
	$this->getMessage($attribute, $rule), $attribute, $rule, $parameters
	));

It would be replaced by something like this only if parameters inclusion is enabled (how this is managed remains to be defined).

$this->messages->add($attribute, (object) [
    'message' => $this->makeReplacements(
        $this->getMessage($attribute, $rule),$attribute, $rule, $parameters
    ),
    'parameters' => $parameters
]);

Things to keep in mind

• Ensure blade @error directive works

Any thoughts ?

Please share your thoughts about this idea and don't hesitate to point out any potential problems.