Why does it throw an error in the view during foreach?

Question

Laravel

Hello, there are three tables which are connected by the relations.
In the controller, we pass data to the template:

$calculators = $request->user()->calculators()->get();
return view('test-view', [ 'temp' => $calculators ]);

When I display in the template
echo $temp[0]->category->name;
, it displays the name of the category, and if so:

echo $temp[0]->category->name;
// или
foreach ($temp as $calculator) {
    echo '<pre>'; var_dump($calculator->category->name); echo '</pre>';
}

then it ends with an error.

Trying to get property of non-object

All entities have categories specified.
How can I get the category name?

Answer 1

When in the template I
echo $temp[0]->category->name;
then displays the name of the category, and if you run it through foreach:

Because in this way you display the name of the category of the first entity, and foreach passes through all, it means that some entity does not have a category

Answer 2

Everything is very simple, one of the $calculator does not have a category, specifically the first one obviously does.
Check like this:

foreach ($temp as $key=>$calculator) {
    echo (isset($calculator->category))?$calculator->category->name:'не задано для '.$key;
}