Error in updating the input field,Laravel - php

Question

So I have this edit form it contains a field for the building name and an image.
The problem is when I try to edit and click update the building name it show this error:
Call to a member function getClientOriginalExtension() on null
But when I change the image and click update its working as long as you don't change the building name.
Here is the code:
editbuilding.blade.php
{!! Form::open(array('route' => ['editbuilding',$id], 'class' => 'form' , 'files'=>'true')) !!}
<div class="container">
<div class="form-group">
{!! Form::label('Building Name') !!}
{!! Form::text('buildingname', $building->name, array('required',
'class'=>'form-control',
'placeholder'=>'Building Name')) !!}
</div>
<div class="form-group">
{!! Form::label('Building Name') !!}
{!! Form::file('buildingpics',
array('onchange'=>'previewFile()')) !!}
#if ($building->picture)
<br/><img src="{{asset('assets/'.$building->picture)}}" id="previewImg" style="height:300px; width:300px;" alt="">
#else
</br><p>No image found</p>
#endif
</div>
<div class="form-group">
{!! Form::submit('Update',
array('class'=>'btn btn-primary')) !!}
Back
</div>
</div>
{!! Form::close() !!}
<script type="text/javascript">
function previewFile() {
var preview = document.querySelector('#previewImg');
var file = document.querySelector('input[type=file]').files[0];
var reader = new FileReader();
reader.addEventListener("load", function () {
preview.src = reader.result;
}, false);
if (file) {
reader.readAsDataURL(file);
}
}
</script>
#endsection
#section('scripts')
#endsection
BuildingController.php
public function saveBuilding(Request $request)
{
$file = $request->file('buildingpics');
$building = new Building();
$building->name = $request->buildingname;
$building->picture = $building->name.'.'.$file->getClientOriginalExtension();
$file->move('assets',$building->name.'.'.$file->getClientOriginalExtension());
$building->save();
\Session::flash('building_flash', 'Created successfully!');
return redirect('/');
}
public function edit($id)
{
$building = Building::find($id);
return view('editbuilding')->withBuilding($building)->with('id',$id);
}
/**
* Update the specified resource in storage.
*
* #param \Illuminate\Http\Request $request
* #param int $id
* #return \Illuminate\Http\Response
*/
public function update(Request $request, $id)
{
$building = Building::find($id);
$building->name = $request->buildingname;
$file = $request->file('buildingpics');
$building->picture = $building->name.'.'.$file->getClientOriginalExtension();
// print_r(FCPATH);
// dd($file);
$file->move('assets',$building->name.'.'.$file->getClientOriginalExtension());
$building->update();
\Session::flash('building_flash', 'Updated successfully!');
return redirect()->back();
}

Answer 1

You have to add test if there is an uploaded file or not :
public function update(Request $request, $id)
{
$building = Building::find($id);
$building->name = $request->buildingname;
$file = $request->file('buildingpics');
if($file != null) {
$building->picture = $building->name.'.'.$file->getClientOriginalExtension();
// print_r(FCPATH);
// dd($file);
$file->move('assets',$building->name.'.'.$file->getClientOriginalExtension());
}
$building->update();
\Session::flash('building_flash', 'Updated successfully!');
return redirect()->back();
}

Answer 2

You should check it first if there is any file posted by the request. You can check it with function:
$request->hasFile('buildingpics');
So your code should be look like:
public function update(Request $request, $id)
{
...
if ($request->hasFile('buildingpics'))
// do saving file and set picture field here
}
...
}