Laravel order by not working on related columns on datatable - laravel

Question

Basically, my backend is:
$columns = array(
0 => 'purchased_date',
1 => 'supplier',
2 => 'purchased_code',
3 => 'grand_total',
4 => 'paid_amount',
5 => 'overall_due_amount',
6 => 'payment_status',
7 => 'action',
);
$limit = $request->input('length');
$start = $request->input('start');
$order = $columns[$request->input('order.0.column')];
$dir = $request->input('order.0.dir');
$query = Purchase::with(['supplier:id,name','purchasePayments']);
$purchased_date = $request->columns[0]['search']['value'];
if (!empty($purchased_date)) {
$query->where('purchased_date', 'like', '%' . $purchased_date . '%');
}
$supplier_search = $request->columns[1]['search']['value'];
if (!empty($supplier_search)) {
$query->whereHas('supplier', function($q) use($supplier_search){
$q->where('name', 'like', '%' . $supplier_search . '%');
});
}
$purchased_code = $request->columns[2]['search']['value'];
if (!empty($purchased_code)) {
$query->where('purchased_code', 'like', '%' . $purchased_code . '%');
}
$totalData = $query->count();
//HERE HOW COULD I ORDER USING SUPPLIER NAME
//suppliers is the name of the table
//and supplier is the relation defined inside purchase model
$order = 'suppliers.name';
$query->orderBy($order, $dir);
if ($limit != '-1') {
$query->offset($start)->limit($limit);
}
$records = $query->get();
$totalFiltered = $totalData;
$data = array();
if (isset($records)) {
foreach ($records as $k => $v) {
$nestedData['id'] = $v->id;
$nestedData['purchased_date'] = \Carbon\Carbon::createFromFormat('Y-m-d H:i:s', $v->purchased_date)->format('Y-m-d');
$nestedData['supplier'] = $v->supplier->name;
$nestedData['purchased_code'] = $v->purchased_code;
$nestedData['grand_total'] = $v->grand_total;
$nestedData['paid_amount'] = $v->purchasePayments->sum('paid_amount');
$nestedData['overall_due_amount'] = $v->overall_due_amount;
$nestedData['payment_status'] = PaymentHelper::getPaymentStatusBadge($v->purchasePayments->last()->payment_status);
$nestedData['action'] = \View::make('admin.purchases.action')->with('r', $v)->render();
$data[] = $nestedData;
}
}
Here, how could I order the full results based on the supplier name. Here, suppliers is the name of the table and supplier is the name of the relation defined on the purchase model. Is there any way to deal with this situation where I need to order based on the related model

Answer 1

It's because eager loading isn't building your query as you anticipate.
// Instead of:
$query->orderBy($order, $dir); ❌
// Use this:
$query->join('suppliers', 'purchases.id', '=', 'suppliers.purchase_id')
->orderBy('suppliers.name', $dir) ✅
To avoid ambiguous column names. i.e: id (Between purchases and suppliers tables.), modify:
// Instead of:
$records = $query->get(); ❌
// Use this:
$records = $query->get(["purchases.*"]); ✅
NOTE: Eager loading still works with the above implementation.