Laravel 5.8 and datatable form validation - laravel

Question

I am using Laravel 5.8 and Yajra datatable package.
I have to build a dynamic form from the controller (it works well).
After submitting the form, when the validation fails, I want to display the old values in the form.
Display the form/datatable and validation work fine. I need the way to display the old values.
Controller (build the form) (just an excerpt as it works fine)
if (request()->ajax())
{
return datatables()
->of($memberships)
->addIndexColumn()
->addColumn('amount', function($data) use ($membership, $amounts) {
$link = '<input type="text" id="membership_id[]" name="membership_id[]" value="' . $data->id . '" style="width:100px" class="form-control">';
$link .= '<input type="number" id="amount[]" name="amount[]" value="">';
return $link;
})
->rawColumns(['amount'])
->make(true);
}
return view('my_blade', compact('memberships', 'id'));
My question here is How to set the value attribute in the amount input field when the validation fails?
my_blade (display datatable form) (just an excerpt as it works fine)
#if (count($errors) > 0)
<div class="alert alert-danger">
<ul>
#foreach ($errors->all() as $error)
<li>{{ $error }}</li>
#endforeach
</ul>
</div>
#endif
<form method="POST" id="my_form" action="{{ route('my_submit_route') }}">
#csrf
<input type="text" id="id" name="id" value="{{ $id }}">
<table id="my_datatable" class="table table-hover table-striped table-responsive">
<thead class="crud-header">
<tr>
<th>No</th>
<th>Name</th>
<th>Description</th>
<th>Status</th>
<th>Amount</th>
</tr>
</thead>
<tbody>
</tbody>
</table>
<div class="form-group row">
<div class="col text-center">
<button type="submit" class="btn btn-primary">
Save
</button>
</div>
</div>
</form>
</div>
</div>
#endsection
#section('script')
<script>
$(document).ready(function() {
/* Start Datatable */
$.ajaxSetup({
headers: {
'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
}
});
$.noConflict();
$('#my_datatable').DataTable({
iDisplayLength: 100,
serverSide: true,
processing: true,
ajax: {
url: "{{ route('my_route', ['id' => $id]) }}",
type: 'GET',
},
columnDefs: [
{className: "dt-center", targets: "_all"}
],
columns: [
{data: 'DT_RowIndex', name: 'DT_RowIndex', orderable: false},
{data: 'name', name: 'name'},
{data: 'given_name', name: 'given_name'},
{data: 'amount', name: 'amount'}
],
order: [[1, 'desc']]
});
/* End Datatable */
});
</script>
#endsection
My validation works fine. Just don't know how to display the old value when validation fails
My Controller (to process form submit)
/* get the array of membership IDs */
$membershipIDs = $request->membership_id;
$validate_array = [];
/* Loop through membership for validation */
for($i = 0; $i < count($membershipIDs); $i++)
{
$validate_array['amount.'. $i] = 'sometimes|nullable|numeric|gte:0';
}
$validator = Validator::make($request->all(), $validate_array);
if ($validator->fails())
{
/* Get the array of amounts */
$amounts = $request->amount;
// How to manage here to return in the form and display the old values and the error message on the failed fields?
}
else
{
//Process the form;
}
My question: How to manage in the controller to return in the form and display the old values and the error messages on the failed fields?
I also use the following for validation, the validation works well but I cannot display the old values in the form after the validation fails.
$this->validate($request, $validate_array);
Thanks

Answer 1

Try this in your controller:
if ($validator->fails()) {
return back()->withInput()->withErrors($validator);
}
Not sure if this also works in Laravel 5. But an alternate to this is:
if ($validator->fails()) {
return redirect('post/create')
->withErrors($validator)
->withInput();
}
Which works in Laravel 5