How to convert null values to empty string in Laravel 5.6 json response?

I have this response from my Laravel 5.6:

{
    "id": 1,
    "name": "Test",
    "email": "[e-mail]",
    "descr": null
}

It comes from this Laravel PHP code:

public function show($id) {
    return Client::find($id);
}

Is there any built-in function in Laravel 5.6 to change the null value to empty sting? I want to get back this json object:

{
    "id": 1,
    "name": "Test",
    "email": "[e-mail]",
    "descr": ""
}

Any idea?

Answer

If you don’t have any choice and you really need it, you can do this using a middleware.

Create a file named NullToBlank.php in the folder app/Http/Middleware with the following code:

<?php

namespace AppHttpMiddleware;

use IlluminateDatabaseEloquentModel;
use Closure;

class NullToBlank
{
    /**
     * Handle an incoming request.
     *
     * @param  IlluminateHttpRequest  $request
     * @param  Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        $output = $next($request);
        if($output instanceof Model)
            return response()->json(array_map(function ($value) {
                return $value === null ? '' : $value;
            }, $output->toArray()));

        return $output;
    }
}

This is the case when you need to change values only on the returned model, not on related models. In the case of returned + all the related models, then the condition if($output instanceof Model) changes to:

if($output instanceof Model) {
    $modelAsArray = $output->toArray();

    array_walk_recursive($modelAsArray, function (&$item, $key) {
        $item = $item === null ? '' : $item;
    });

    return response()->json($modelAsArray);
}

In your app/Http/Kernel.php make sure you add:

AppHttpMiddlewareNullToBlank::class,

under $middleware.

This should do the trick. I haven’t tested it personally, I just did on the go, if you have problems, let me know.

Luca