I am practising Laravel and building a blog for Activity holidays.

I have a posts table which describes the holidays, then an activities table which just has the activity name. I have a joins table that links between them. The two tables share a many-to-many relationship. What I am struggling to achieve is that I would like to add 1 or more activities in the to the table using the select form when adding the posts. Currently it is not registering the activities table but creating the posts to my blog.

I would be grateful for any advise and assistance

See my relevant code below:

// App\ActivityController

namespace App\Http\Controllers;

use App\Activity;
use Illuminate\Http\Request;

class ActivityController extends Controller
{
    protected $fillable = [
      'activity_name'
    ];

    public function posts()
    {
        return $this->belongsToMany('App\Post')->using('App\activityPost')->withTimestamps();

    }
   
    public function create()
    {

        return view('activities.create');
    }

    public function store()
    {
      $activity = new Activity;
      $activity->activity_name = request('activity_name');
      $activity->save();
      return redirect('activities/create');
    }

 
}



// App\PostController

namespace App\Http\Controllers;

use App\Post;
use Carbon\Carbon;
use Illuminate\Http\Request;


class PostController extends Controller
{

    public function __contruct()
    {
        $this->middleware('auth')->except(['index', 'show']);
    }
    

   

    public function create()
    {
      $activities = \App\Activity::pluck('activity_name', 'activity_name');
        return view('posts.create', compact('activities'));


    }

    public function store(Request $request)
    {
        $this->validate(request(), [
            'title' => 'required',
            'body' => 'required',

        ]);
      Post::create([
        'title' =>request('title'),
        'body' =>request('body'),
        'user_id' => auth()->id()
      ]);



        return redirect('/');
    }
        public function activities()
    {
        return $this->belongsToMany('App\Activity')->using('App\activityPost');
    }
 



}


//App\Post.php

namespace App;

class Post extends Model

{
    public function activities()
    {
        return $this->belongsToMany('App\Activity');
    }
    

}




// App\Activity.php

namespace App;


class Activity extends Model
{
    protected $table = 'activities';
    protected $fillable = ['activity_name'];

    public function posts()
    {
        return $this->belongsToMany('App\Post');
    }
    public function index()
    {
        $activities = Activity::orderBy('activity_name', 'asc')->paginate(10);
        return view('activities.index', ['activities'=>$activities]);
    }
    public function store()
    {
        return $this->belongsToMany('App\Post');
    }

    public function create()
    {
        return view ('activities.create');
    }


}



// Routes\web.php

<?php


Route::get('/', 'PostController@index')->name('home');
Route::get('/posts/create', 'PostController@create');
Route::post('/posts', 'PostController@store');

Route::get('/posts/activities/{activity}', 'ActivityController@index');
Route::get('/activities/create', 'ActivityController@create');
Route::post('/activities', 'ActivityController@store');

// resources\views\posts.create.blade.php

<form method="POST" action="/posts">

{{csrf_field() }}

<div class="form-group">
    <label for="title">Name</label>
    <input type="text" class="form-control" id="title" name="title" required>
</div>

<div class="form-group">
    <label for="body">Description</label>
    <textarea name="body" id="body" class="form-control" required></textarea>
</div>


<!-- create form with select multiple
convert activity into array -->


<div class="form-group">
  <label for="activities">Select your Activity</label>
  <select class="form-control" name="activities" size="{{$activities->count()}}" required multiple>
    @foreach ($activities as $activity)
    <option value="activities">
      {{$activity}}
    </option>
        @endforeach
  </select>
</div>



<div class="form-group">
    <button type="submit" class="btn btn-primary">Publish</button>
</div>

</form>


//ActivityPost Table

  public function up()
    {
        if(!Schema::hasTable('activity_post')) {
            Schema::create('activity_post', function (Blueprint $table) {
                $table->integer('activity_id')->unsigned()->index();
                $table->foreign('activity_id')->references('id')->on('activities')->onDelete('cascade');

                $table->integer('post_id')->unsigned()->index();
                $table->foreign('post_id')->references('id')->on('posts')->onDelete('cascade');

            });
        }
    }

//Activity Table

    public function up()
    {
        if(!Schema::hasTable('activities')) {
            Schema::create('activities', function (Blueprint $table) {
                $table->increments('id');
                $table->string('activity_name');
                $table->timestamps();
            });
        }
    }


//Posts Table

    public function up()
    {
            if(!Schema::hasTable('posts')){
            Schema::create('posts', function (Blueprint $table) {
                $table->increments('id');
                $table->integer('user_id');
                $table->string('title');
                $table->text('body');
                $table->timestamps();
                });
            }
    }