Your route is calling a controller, but not the function in the controller as @nepras mentions. Your route should be:

Route::get('/{id}/','PostsController@show');

or

Route::get('/{id}',['as' => 'id','uses' => 'PostsController@show']);

Thank you for your replies.

rberlin01 said:

Your route is calling a controller, but not the function in the controller as @nepras mentions.

This is RESTful Controller, by defining this route:

Route::resource('/', 'PostsController');

I can use these methods: index, create, store, show, edit, update, destroy

docs

This solution is worked for me, but after doing so, I needed to define other route like so either:

Route::resource('/', 'PostsController');
Route::get('/{id}', 'PostsController@show');
Route::get('/{id}/edit', 'PostsController@edit');
Route::put('/{id}', 'PostsController@update');
Route::delete('/{id}', 'PostsController@destroy');

Anyway, thank you!