render function in Handler.php not working Laravel 8 - php

Question

I want to return a JSON response instead of the default 404 error page when ModelNotFoundException occurs. To do this, I wrote the following code into app\Exceptions\Handler.php :
public function render($request, Exception $exception)
{
if ($exception instanceof ModelNotFoundException) {
return response()->json([
'error' => 'Resource not found'
], 404);
}
return parent::render($request, $exception);
}
However it doesn't work. When the ModelNotFoundException occurs, Laravel just shows a blank page. I find out that even declaring an empty render function in Handler.php makes Laravel display a blank page on ModelNotFoundException.
How can I fix this so it can return JSON/execute the logic inside the overriden render function?

Answer 1

In Laravel 8x, You need to Rendering Exceptions in register() method
use App\Exceptions\CustomException;
/**
* Register the exception handling callbacks for the application.
*
* #return void
*/
public function register()
{
$this->renderable(function (CustomException $e, $request) {
return response()->view('errors.custom', [], 500);
});
}
For ModelNotFoundException you can do it as below.
use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
public function register()
{
$this->renderable(function (NotFoundHttpException $e, $request) {
return response()->json(...);
});
}
By default, the Laravel exception handler will convert exceptions into an HTTP response for you. However, you are free to register a custom rendering Closure for exceptions of a given type. You may accomplish this via the renderable method of your exception handler. Laravel will deduce what type of exception the Closure renders by examining the type-hint of the Closure:
More info about the error exception

Answer 2

This code doesn't work for me (in Laravel 8.74.0):
$this->renderable(function (ModelNotFoundException$e, $request) {
return response()->json(...);
});
Don't know why, but ModelNotFoundException is directly forwarded to NotFoundHttpException (which is a part of Symfony Component) that used by Laravel and will ultimately triggers a 404 HTTP response. My workaround is checking the getPrevious() method of the exception:
$this->renderable(function (NotFoundHttpException $e, $request) {
if ($request->is('api/*')) {
if ($e->getPrevious() instanceof ModelNotFoundException) {
return response()->json([
'status' => 204,
'message' => 'Data not found'
], 200);
}
return response()->json([
'status' => 404,
'message' => 'Target not found'
], 404);
}
});
And then we will know that this exception come from ModelNotFoundException and return a different response with NotFoundHttpException.
Edit
This is why ModelNotFoundException thrown as NotFoundHttpException

Answer 3

This one is my Handler file:
use Throwable;
public function render($request, Throwable $exception)
{
if( $request->is('api/*')){
if ($exception instanceof ModelNotFoundException) {
$model = strtolower(class_basename($exception->getModel()));
return response()->json([
'error' => 'Model not found'
], 404);
}
if ($exception instanceof NotFoundHttpException) {
return response()->json([
'error' => 'Resource not found'
], 404);
}
}
}
This one is only for all request in API route. If you want to catch all request, so remove the first if.

Answer 4

Please note that by default Laravel emits a JSON representation of an exception ONLY when you send a request with the header parameter Accept: application/json! For all other requests, Laravel sends normal HTML rendered output.