Laravel 5 session()->keep method not working - laravel

Question

I have a view with an input date field and a table beneath that. The table is populated based on the date entered. When the date is entered I use a POST method on the form which handles the DB request and returns the same view with the data. I'd like to also return the original date that was entered. I tried session()->keep and flashOnly methods. None return the input date to the view.
My controller:
public function groupTestAthletes(Request $request)
{
$inputDate = null;
$tests = null;
if ($request['tgroupdate']){
$inputDate = Carbon::createFromFormat('d/m/Y', $request['tgroupdate']);
$tests = Test::where('test_date', '=', $inputDate->format('Y-m-d'))
->orderBy('athlete_id', 'desc')
->get();
}
$request->session()->keep(['tgroupdate']);
//$request->flashOnly(['tgroupdate']);
return view('npr.test_athletes', ['tests' => $tests]);
My view:
<form class="form-inline" role="form" method="POST" action="{{ route('admin.search_tgroup') }}">
{{ csrf_field() }}
<div class="form-group">
<label for="tgroupdate" class="control-label">Test Date</label>
<div class="input-group date" id="testgroupdatepicker">
<input name="tgroupdate" type="text" style="background-color:#ffffff" readonly=""
value="{{ Session::get('tgroupdate') }}" class="form-control">
<div class="input-group-addon">
<span class="glyphicon glyphicon-th"></span>
</div>
</div>
</div>
<div class="form-group">
<button type="submit" class="btn btn-primary">Search Athletes
</button>
<input type="hidden" name="_token" value="{{ Session::token()}}">
</div>
</form>

Answer 1

You dont need to save the date in session. You can save the date in a variable,send it to the view and in the view you can check if variable exist using isset php function.
In Controller
public function groupTestAthletes(Request $request)
{
$inputDate = null;
$tests = null;
if ($request['tgroupdate']){
$inputDate = Carbon::createFromFormat('d/m/Y', $request['tgroupdate']);
$tests = Test::where('test_date', '=', $inputDate->format('Y- m-d'))
->orderBy('athlete_id', 'desc')
->get();
}
return view('npr.test_athletes', ['tests' => $tests,'selected_date' => $request['tgroupdate']]);
And in the view,
<form class="form-inline" role="form" method="POST" action="{{ route('admin.search_tgroup') }}">
{{ csrf_field() }}
<div class="form-group">
<label for="tgroupdate" class="control-label">Test Date</label>
<div class="input-group date" id="testgroupdatepicker">
<input name="tgroupdate" type="text" style="background-color:#ffffff" readonly=""
value="#if(isset($selected_date)) $selected_date #endif" class="form-control">
<div class="input-group-addon">
<span class="glyphicon glyphicon-th"></span>
</div>
</div>
</div>
<div class="form-group">
<button type="submit" class="btn btn-primary">Search Athletes
</button>
<input type="hidden" name="_token" value="{{ Session::token()}}">
</div>
</form>
Edit: This minor change in the view gave the optimal solution.
value="#if(isset($selected_date)){{$selected_date}}#endif"