Undefined URL value

Look at however/wherever you are generating that url in your view or javascript. I'm thinking this is from javascript since php would generally give you an error, but javascript will return "undefined" for something that doesn't exist. Are you using js to build these urls?

Controller

public function add_student(MyClass $my_class)
    {

        $role = Role::where('name', 'shs-student')->first();
        $students = $role->users;

        $users = User::withTrashed()->get();

        return view('my_class.add_student', compact('my_class', 'students', 'users'));
    }

public function list(MyClass $my_class)
        {

            // print_r($my_class);
            // die();
            
            return response()->json($my_class);
        }

Route

Route::get('view/add-student/{my_class}','StudentController@add_student')->name('my_class.add_student');

Route::get('list', 'MyClassController@list')->name('my_class.list');

Blade

<a :href="'add-student/' + my_class.id" class="ui mini green icon button"><i class="plus icon"></i>

Vue.js

getMy_Class(){
            axios.get('{{ route('my_class.list', $my_class->id) }}')
            .then(response => {
                this.my_class = response.data;
            })
            .catch(error => {
                console.log(error.response.data);
            });
        },

@CRONIX - yeah, I've been using vue.js for this, and somewhat thinking to change it to pure php

@TYKUS - yeah, probably it's because of the js, can you suggest a better way for this thing, I'm just willing to learn someways since then

You also have to ask yourself, how come I can see public in my URLs

So in this

<a :href="'add-student/' + my_class.id" 

my_class.id is undefined so you end up with undefined in your URL