Laravel ORM relationship returns error when value not present in DB - laravel

Question

I have an issue with querying relationships.
I am querying relations between Projects, Companies and Products. However, whenever a Project ID is not present in the database an fatal exception is trown:
Call to a member function companies() on a non-object
public function index($i) {
return $this->returnTop($i, Array(
'projectid' => 5,
'products' => Array(1, 2, 3)
)
);
}
public function returnTop($count = 6, $args = Array()) {
$companies = Project::find($args['projectid'])->companies()->whereHas('products', function($q) use($args) {
$q->whereIn('products.id', $args['products']);
})->with('products')->limit($count)->get();
return Response::json($companies);
}
Now, I know that project id 5 is not present in the DB, and this is likely to be the cause of this error, but I want to return a message instead of the application throwing a fatal error....
Any ideas?

Answer 1

Just check if find() returns null. Something like this:
$project = Project::find($args['projectid']);
if(is_null($project)){
return Response::json(['message' => 'Project not found']);
}
$companies = $project->companies()->whereHas('products', function($q) use($args) {
$q->whereIn('products.id', $args['products']);
})->with('products')->limit($count)->get();
return Response::json($companies);
An alternative would be findOrFail which throws a ModelNotFoundException. You could handle the exception globally or catch it inside the controller:
try {
$companies = Project::findOrFail($args['projectid'])->companies()->whereHas('products', function($q) use($args) {
$q->whereIn('products.id', $args['products']);
})->with('products')->limit($count)->get();
return Response::json($companies);
} catch (\Illuminate\Database\Eloquent\ModelNotFoundException $e){
return Response::json(['message' => 'Project not found']);
}

Answer 2

You first have to test whether the returned object is actually not null. Blindly assuming a database query succeeds is waiting for sh*t to hit the fan.
public function returnTop($count = 6, $args = Array()) {
$project = Project::find($args['projectid']);
if($project) {
$companies = $project->companies()->whereHas('products', function($q) use($args) {
$q->whereIn('products.id', $args['products']);
})->with('products')->limit($count)->get();
return Response::json($companies);
}
else {
return; // .. your error or whatever
}
}
Also the "call to a member function on a non-object" is quite specific, it tells you that a method (member function) could not be called due to the fact that you are trying to call it on a non-object.