laravel-beginning/form-app/app/Http/Controllers/FormController.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use Illuminate\Support\Facades\File;
use Carbon\Carbon;

class FormController extends Controller
{
    private $path;

    public function __construct()
    {
        $this->path = storage_path('app/forms/contacts.json');
    }
    
    public function index() 
    {
        return view('form');
    }

    public function submit(Request $request)
    {
        $validated = $request->validate([
            'name' => 'required|string|min:3|max:15',
            'email' => 'required|email|max:50',
            'message' => 'required|string|min:10|max:100'
        ]);

        File::ensureDirectoryExists(dirname($this->path));

        $data = [];
        if (File::exists($this->path)) {
            $content = File::get($this->path);
            $data = json_decode($content, true) ?: [];
        }

        $validated['created_at'] = now()->toDateTimeString();
        $data[] = $validated;

        File::put($this->path, json_encode($data, JSON_UNESCAPED_UNICODE));

        return redirect()->back()->with('success', 'Данные сохранены!');
    }

    public function showData() 
    {
        $data = [];
        if (File::exists($this->path)) {
            $content = File::get($this->path);
            $data = json_decode($content, true) ?: [];
        }

        $submissions = collect($data)->map(function ($item) {
            return (object) [
                'name' => $item['name'],
                'email' => $item['email'],
                'message' => $item['message'],
                'created_at' => Carbon::parse($item['created_at'])
            ];
        }) -> sortBy('createdAt');

        return view('admin', compact('submissions'));
    }
}