如何在laravel中验证json数据？

My code to validate data like this :

public function register(Request $request)
{
    //echo '<pre>';print_r($request->all());echo '</pre>';die();
    $this->validate($request, [
        'email'=>'required',
        'password'=>'required',
        'data_cache.dataCache.id'=>'required|numeric'
        'data_cache.dataCache.quantity'=>'required|numeric'
    ]);
}

The result of echo '<pre>';print_r($request->all());echo '</pre>';die(); like this :

Array
(
    [data_cache] => {"dataCache":{"id":112,"quantity":1,"information":"stamford bridge","request_date":"15-08-2017 02:30:00"},"expired":"2017-08-14T16:30:26.272Z"}
    [email] => chelsea@gmail.com
    [password] => 87654321
)

The data_cache is json data

On the view blade, I add this to display the message validation :

@if ($errors->has('data_cache'))
    <span class="help-block">
        <strong>{{ $errors->first('data_cache') }}</strong>
    </span>
@endif

If the code executed, there is no display message validation

Seems the validation json data is still wrong

How can I do it correctly?