Use a parameter from URL in a controller Laravel 5.8.22 - php

Question

I'm trying to pass anINT from this URL: myapp.build/courses/anINT (implemented in the CoursesController) to $id in the Lesson_unitsController function below. I've tried a lot of solutions, but I can't seem to get it right.
The function in the CoursesController which implements the url is:
public function show($id)
{
$course = Course::find($id);
return view('courses.show')->with('course', $course);
}
Part of the show.blade.php file is:
#if(!Auth::guest())
#if(Auth::user()->id == $course->user_id)
Edit Course
Lesson Units
{!!Form::open(['action'=> ['CoursesController#destroy', $course->id], 'method' => 'POST', 'class' => 'float-right'])!!}
{{Form::hidden('_method', 'DELETE')}}
{{Form::submit('Delete', ['class' => 'btn btn-danger'])}}
{!!Form::close()!!}
#endif
#endif
The Lesson_unitsController functions are:
public function index()
{
$lesson_units = Lesson_unit::orderBy('title','asc')->paginate(10);
return view('lesson_units.index')->with('lesson_units', $lesson_units);
}
public function specificindex($id)
{
$course = Course::find($id);
return view('lesson_units.specificindex')->with('lesson_units', $course->lesson_units);
}
And the specificindex.blade.php file is:
#extends('layouts.app')
#section('content')
<div class="container">
<div class="row justify-content-center">
<div class="col-md-8">
<div class="card">
<div class="card-header">Dashboard</div>
<div class="card-body">
Create lesson unit
<p>
<h3>Your lesson_units</h3>
#if(count($lesson_units) > 0)
<table class="table table-striped">
<tr><th>Title</th><th></th><th></th></tr>
#foreach($lesson_units as $lesson_unit)
<tr><td>{{$lesson_unit->title}}</td>
<td>Edit</td>
<td>
{!!Form::open(['action'=> ['Lesson_unitsController#destroy', $lesson_unit->id], 'method' => 'POST', 'class' => 'float-right'])!!}
{{Form::hidden('_method', 'DELETE')}}
{{Form::submit('Delete', ['class' => 'btn btn-danger'])}}
{!!Form::close()!!}
</td>
</tr>
#endforeach
</table>
#else
<p>You have no lesson unit.</p>
#endif
#if (session('status'))
<div class="alert alert-success" role="alert">
{{ session('status') }}
</div>
#endif
You are logged in!
</div> </div> </div> </div> </div>
#endsection
The routes in web.php are:
Route::resource('courses', 'CoursesController');
Route::resource('lesson_units', 'Lesson_unitsController');
Route::get('/courses/{id}', 'Lesson_unitsController#specificIndex');
I want that when the link for Lesson Units is clicked on the page, the id in the url is passed to the specificindex function in the Lesson_unitsController. Now, I get just a blank page. What am I doing wrong?

Answer 1

Try to understand the concept of RESTful and CRUD.
By using Route::resource('courses', 'CoursesController');, Laravel has helped you to register the following routes:
Route::get('courses', 'CoursesController#index');
Route::get('courses/create', 'CoursesController#create');
Route::post('courses/{course}', 'CoursesController#store');
Route::get('courses/{course}/edit', 'CoursesController#edit');
Route::put('courses/{course}', 'CoursesController#update');
Route::delete('courses/{course}', 'CoursesController#destroy');
Then, when you make GET request to myapp.build/courses/123, Laravel will pass the request to the show function of your CoursesController like:
public function show(Course $course)
{
return view('lesson_units.index')->with('lesson_units', $course->lesson_units);
}
Laravel will automatically resolve the Course from your database using the parameter passed into the route myapp.build/courses/{course}.
Note: The variable name $course has to match with the one specify in route /{course}.

Answer 2

You don't have a route set up to handle the $id coming in. The resource method within the Route class will provide a GET route into your Lesson_unitsController controller without an expectation of any variable. It is the default index route, and by default doesn't pass a variable.
There are a couple of ways to do this, but the easiest is to just create a new route for your specific need:
Route::get('lesson_units/{id}', 'Lesson_unitsController#specificIndex');
And then make your specificIndex function in your controller with an incoming variable:
public function specialIndex($id)
{
$course = Course::find($id);
// return view to whatever you like
}
HTH