Laravel 5.3 View Composer - 更改从控制器传递到视图的数据

Im getting a bit confused at how to work View Composers in Laravel and i thought i might ask some advice.

For example, my website has plans, in plans table i have the usual ID etc etc but i also have 'space_allowed' which is represented my a number, i have represented 'unlimited' as NULL so that i dont have to change any of my (count) functionalities.

So, in my controller i have something like this

$plans = Plan::where('is_active', 1)->get();
return view('pricing', ['plans' => $plans]);

Now when im in the view i just @foreach over the plans and spit out the details.

BUT, since im storing 'unlimited' space as NULL, the view then reflects that.

So i figure that since ill be referencing this all over the site, it would be a good idea to check if the value is null, and if it is, return 'unlimited' instead, and if the value isnt null, then just spit it out as normal in one place.

Hence the idea for the view composer.

So i have created the ComposerServiceProvider.php, added the boot and register methods and inside the boot method i have the following:

View::composer('*', function ($view) {
});

So i think im almost there.

But im lost on how to implement the code that goes in that closure to check if the storage_allowed is null

Any help would be greatly appreciated.

You can do this in view composer only by duplicating a lot of data, so just do this check in Blade template:

@foreach ($plans as $plan)
    ....
    {{ empty($plan->space) ? 'Unlimited' : $plan->space }}
    ....
@endforeach

Something that is sometimes useful is to add attributes purely for display. I normally postfix these with "nice" so in your case above

class Plan extends Model {

    public function getSpaceNiceAttribute(){
        return is_null($this->space) ? 'Unlimited' : $this->space;
    }

}

Then in your template you can just use {{ $plan->space_nice }}

The benefit of this method is that it keeps the output consistent anywhere you need this logic rather than replicated it everywhere in your templates and allows for more conditionals (e.g. if you wanted to display "none" instead of "0" you could make the the in just this function and all your templates will reflect it).

Probably a bit late for you but I'll just post for future reference. Whatever you pass to the view from your controller is accessible in the closure that you access in the composer method. So, for example if you had a page variable that you passed along from the controller, you would be able to access it from the closure like this:

public function compose(View $view)
{
    $page = $view->getData()['page'];
    $data = ['menu' => $this->generateSideBarHTML($page)];
    $view->with($data);
}

Now, you can access the $menu from your blade template. For your example it would be something like this:

public function compose(View $view)
{
    $plans = $view->getData()['plans'];
    //Iterate on the plans here...
    $view->with($data);
}