[YAJRA-DATATABLE]Cannot get pivot object on eager load many to many relationship

I don't know how to get the pivot object of the M2M relationship on this package. show me an exhaustive tutorial how to get the pivot object as well as the related data on the model object. I don't know how to render that data on dataTable() too

returned data

{
    data: [
        {
            id: 1,
            name: "aaaa",
            groupmap:[
                {
                    id: 1,
                    name: "a",
                    number: "123123",
                    pivot: {
                        id: 1,
                        group_id: 2,
                        contact_id: 3
                    }
                },
                {
                    id: 2,
                    name: "b",
                    number: "1",
                    pivot: {
                        id: 3,
                        group_id: 6,
                        contact_id: 7
                    }
                },
            ]
        },
        {
            id: 2,
            name: "ddddd",
            groupmap:[
                {
                    id: 1,
                    name: "ww",
                    number: "7777",
                    pivot: {
                        id: 1,
                        group_id: 2,
                        contact_id: 3
                    }
                },
                {
                    id: 2,
                    name: "6666",
                    number: "234234",
                    pivot: {
                        id: 7,
                        group_id: 3,
                        contact_id: 1
                    }
                },
            ]
        },

    ]
}

Code

$groupModelWith = GroupModel::with('groupmap')->select('group.*')->where('id', $gid);

     return datatables()->of($groupModelWith)
         ->addColumn('group-name', function ($groupModelMember) {
             // get groupmap->name
         })
         ->addColumn('group-number', function ($groupModelMember) {
             // get groupmap->number
         })
         ->addColumn('action', function ($groupModelMember) {
             // get pivot->id
         })
         ->addIndexColumn()
         ->make(true);

System details

• Operating System: Windows 10
• PHP Version: v7.1.0
• Laravel Version: 5.6.39
• Laravel-Datatables Version: 1.2.0