method links does not exist - laravel 5.4 - laravel

Question

I am using filter by serial number in table,, but when I click the button error like this
" method links does not exist"
this is my controller
public function show(Request $request)
{
$instrument = Instrument::when($request->serial_number, function ($query) use ($request) {
$query->where('serial_number', 'like', "%{$request->serial_number}%");
})->paginate(5);
$instrument->appends($request->only('serial_number'));
return view('settinginstrument.index', compact('settinginstrument'));
}
this is my blade:
<table class="table">
#foreach ($instruments as $instrument)
<tr>
<td>
Serial Number : {{ $instrument->serial_number }}
#if($instrument->customer !== NULL)
<div class="text-muted"><i class="fa fa-hospital-o" aria-hidden="true"></i> {{ $instrument->customer->name }}</div>
#endif
#if($instrument->contractType !== NULL)
<div class="text-muted"><i class="fa fa-compress" aria-hidden="true"></i> {{ $instrument->contractType->name }}</div>
#endif
</td>
<td>
<div class="pull-right">
<a type="button" href="{{ route('instrument.edit', ['instrumentType' => $instrumentType->id, 'instrument' => $instrument->id]) }}"
class="btn btn-success ">
<i class="fa fa-pencil"></i> Edit
</a>
#if($instrument->customer == NULL || $instrument->contractType == NULL)
<a href="{{ route('instrument.destroy', ['instrumentType' => $instrumentType->id, 'instrument' => $instrument->id]) }}"
data-method="delete" data-confirm="" class="btn btn-danger">
<i class="fa fa-trash"></i> <span class="hidden-xs">Delete</span>
</a>
#endif
</div>
</td>
</tr>
#endforeach
</table>
<div class="paginator text-center">{{ $instruments->links() }}</div>
#else
....................................
where wrong with my code?

Answer 1

You are not passing the param to the view:
public function show(Request $request)
{
$instruments = Instrument::when($request->serial_number, function ($query) use ($request) {
$query->where('serial_number', 'like', "%{$request->serial_number}%");
})->paginate(5);
$instrument->appends($request->only('serial_number'));
return view('settinginstrument.index',['instruments' => $instruments);
}
Then on the blade:
{{$instruments->links()}}

Answer 2

When you have zero counts of record and you are trying to access the links() then such issue occurs
Add on condition to check the record exists.
#if($instruments)
<div class="paginator text-center">{{ $instruments->links() }}</div>
#endif
Also in the controller you have one typo error $instruments and $instrument
I recommend that add the condition above the foreach
and on blank result show some message that record not found.
Update
Also pass the $instruments to the balde
$instruments = Instrument::when($request->serial_number, function ($query) use ($request) {
$query->where('serial_number', 'like', "%{$request->serial_number}%");
})->paginate(5);
$instruments->appends($request->only('serial_number'));
return view('settinginstrument.index', compact('instruments'));