Backpack 4.1 BelongsToMany with pivot data

App\Http\Controllers\UserCrudController

<?php

namespace App\Http\Controllers;

use Backpack\CRUD\app\Http\Controllers\CrudController;
use Backpack\CRUD\app\Library\CrudPanel\CrudPanelFacade as CRUD;

class UserCrudController extends CrudController
{
    use \Backpack\CRUD\app\Http\Controllers\Operations\ListOperation;
    use \Backpack\CRUD\app\Http\Controllers\Operations\CreateOperation { store as traitStore; } //IMPORTANT HERE
    use \Backpack\CRUD\app\Http\Controllers\Operations\UpdateOperation { update as traitUpdate; } //IMPORTANT HERE
    use \Backpack\CRUD\app\Http\Controllers\Operations\DeleteOperation;
    use \Backpack\CRUD\app\Http\Controllers\Operations\ShowOperation;

    public function setup()
    {
        CRUD::setModel(\App\Models\User::class);
        CRUD::setRoute(config('backpack.base.route_prefix') . '/user');
        CRUD::setEntityNameStrings('user', 'users');
    }

    protected function setupListOperation()
    {
        CRUD::column('name');
    }

    protected function setupCreateOperation()
    {
        CRUD::field('name');
        
        CRUD::field('roles_list')
            ->type('repeatable')
            ->label('Roles')
            ->fields([
                [
                    'name' => 'role_id',
                    'type' => 'select2',
                    'model' => 'App\Models\Role',
                    'attribute' => 'name'
                ],
                [
                    'name' => 'pivot_field',
                    'type' => 'text'
                ]
            ]);
    }

    protected function setupUpdateOperation()
    {
        $this->setupCreateOperation();
    }

    protected function setupShowOperation()
    {
        CRUD::column('name');
    }

    public function store()
    {
        $roles = collect(json_decode(request('roles_list'), true));

        $response = $this->traitStore();

        $this->crud->entry->roles()->sync($roles);

        return $response;
    };

    public function update()
    {
        $roles = collect(json_decode(request('roles_list'), true));

        $response = $this->traitUpdate();

        $this->crud->entry->roles()->sync($roles);

        return $response;
    }

App\Models\User

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class User extends Model
{
    use \Backpack\CRUD\app\Models\Traits\CrudTrait;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name',
    ];

    /**
     * The attributes that should be cast to native types.
     *
     * @var array
     */
    protected $casts = [
        'id' => 'integer',
    ];

    public function roles()
    {
        return $this->belongsToMany(\App\Models\Role::class)->withPivot('pivot_field'); //IMPORTANT: use withPivot!
    }
    
    //acessor to get the roles populated in the repeatable field again
    public function getRolesListAttribute() {
        return json_encode($this->roles->map(function($role) {
            return ['role_id' => $role->id, 'pivot_field' => $role->pivot->pivot_field];
        }));
    }
}

@pxpm - can you rename these files to add the .php extension? Without it there's no syntax highlighting 🙏

The update may generate duplicate records in the pivot table, I encounter this issue.

This is a behavior of the sync method. Then I found the solution

So, for update method, transform the int key into a random string.

$roles = [];
foreach(json_decode(request('roles_list'), true) as $role)
{
    $jobs[Str::random(5)] = $role;
}

Then, the duplication of pivot entries will not happen. Hope it helps.

@kiddtang To avoid this behaviour, saving the main model, we remove all related relations and resave them all from scratch based on what we receive