The relationship in the data table is empty

Question

I'm getting this error in DataTables: DataTables warning: table id=DataTables_Table_0 - Exception message:

Attempted to read null property "name".

Although each position_id has an id in the position table, so it should not be empty. If anyone would like to help I would be grateful. My model:

public function position()
    {
        return $this->belongsTo(Position::class);
    }

My controller:

class EmployeeController extends Controller
{
    public function index(Request $request)
    {
        if ($request->ajax()) {
            $data = Employee::with('position')->select('id','name','email')->get();
            return Datatables::of($data)->addIndexColumn()
            ->addColumn('position', function (Employee $employee) {
                return $employee->position->name;
            })->addColumn('action', function($data){
                    $button = '<button type="button" name="edit" id="'.$data->id.'" class="edit btn btn-primary btn-sm"> <i class="bi bi-pencil-square"></i>Edit</button>';
                    $button .= '   <button type="button" name="edit" id="'.$data->id.'" class="delete btn btn-danger btn-sm"> <i class="bi bi-backspace-reverse-fill"></i> Delete</button>';
                    return $button;
                })
                ->make(true);
        }

        return view('admin.employees.index');

    }
}

script:

$(document).ready(function() {
        var table = $('.user_datatable').DataTable({
            processing: true,
            serverSide: true,
            ajax: "{{ route('admin.employees.index') }}",
            columns: [
                {data: 'id', name: 'id'},
                {data: 'name', name: 'name'},
                {data: 'email', name: 'email'},
                {data: 'position', name: 'position.name'},
                {data: 'action', name: 'action', orderable: false, searchable: false},
            ]
        });

migrate:

public function up()
    {
        Schema::create('employees', function (Blueprint $table) {
            $table->id();
            $table->string('name');
            $table->foreignId('position_id')->nullable();
            $table->string('phone_number');
            $table->date('recruitment_date');
            $table->string('email')->unique();
            $table->string('image_path')->nullable();
            $table->string('payment');
            $table->timestamps();
            $table->string('admin_created_id')->nullable();
            $table->string('admin_updated_id')->nullable();
        });
    }

Answer 1

This error means that when the Datatable tries to get data from $data, there is no collection or array to locate it inside the get() method

{ collection[0]{
0 => 'Models/Employees'[0],
1 => 'Models/Employees'[1]
}

So when you look at $raw the above returns no position or attributes

From that point on, we will change the controller to look like this

public function index(Request $request)
    {
        if ($request->ajax()) {
            $data = Employee::query()->with('position')->select('id','name','email')->get();
            return Datatables::of($data)->addIndexColumn()
            ->addColumn('position', function (Employee $employee) {
                return $employee->position->name;
            })->addColumn('action', function($data){
                    $button = ' Edit';
                    $button .= '     Delete';
                    return $button;
                })
                ->make(true);
        }

        return view('admin.employees.index');

    }

If that doesn't work, you can try changing the database query But for this I need to dump $data You can see the result in the Network section of the Inspect element in your browser dd($data);

Answer 2

The problem is because of choice. It seems that if you want to use relations you have to add a foreign key to the select (in my case "position_id"), or remove it completely and just use get . Thanks to everyone who helped in the comments.