Global variable in laravel controller

问题

I want the $year variable to be available in all functions of my PagesController. I tried this code but I didn't succeed.

class PagesController extends Controller
{
    public function __construct()
    {
        $dt = Carbon::parse();
        $year = $dt->year;
    }

    public function index()
    {
        return view('pages.index');
    }

    public function about()
    {
        return view('pages.about', compact('year'));
    }

    public function create()
    {
        return view('pages.create', compact('year'));
    }
}

回答1:

1. Option: Use the AppServiceProvider

In this case $year is available to ALL views!

<?php

namespace App\Providers;

use Carbon;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        view()->share('year', Carbon::parse()->year);
    }

    /**
     * Register the service provider.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}

2. Option: Use a View Composer

In this case, the variable is only available to the views where you need it.

Don't forget to add the newly created provider to config/app.php!

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Carbon;

class ComposerServiceProvider extends ServiceProvider
{
    /**
     * Register bindings in the container.
     *
     * @return void
     */
    public function boot()
    {
        // Using Closure based composers...
        view()->composer('pages.*', function ($view) {
            $view->with('year', Carbon::parse()->year);
        });
    }

    /**
     * Register the service provider.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}

3. Use Blades @inject-method

Within the views that need the year you could inject a Carbon instance like this:

@inject('carbon', 'Carbon\Carbon')

{{ $carbon->parse()->year }}

回答2:

Try this:

//give private declaration
private $year;
public function __construct()
{
    $dt = Carbon::parse();
    $this->year = $dt->year;
}

public function index()
{
    return view('pages.index');
}

public function about()
{
    $year = $this->year;
    return view('pages.about',compact('year') );
}

public function create()
{
     $year = $this->year;
    return view('pages.create',compact('year') );
}

回答3:

You can create a global singleton within App::before event

App::before(function($request) {
    App::singleton('customYear', function(){
        $dt = Carbon::parse();
        $customYear = $dt->year;
        return $customYear;
    });

    // If you use this line of code then it'll be available in any view
    View::share('customYear', app('customYear'));

    //To get the same data in any controller you may use:
    $customYear = app('customYear');
});

来源：https://stackoverflow.com/questions/32942379/global-variable-in-laravel-controller