Broken default value for Code/JSON fields

[jacob418]

• Laravel Version: 8.75.0
• Nova Version: 3.30.0
• PHP Version: 8.0.9
• Database Driver & Version: Docker-Image: postgres:13
• Operating System and Version: Linux 5.4.0-96-generic
• Browser type and version: Google Chrome/96.0.4664.110

Description:

For fields of type \Laravel\Nova\Fields\Code with the mode = application/json option it is not possible to define default values via the \Laravel\Nova\Fields\Code::default method.

Detailed steps to reproduce the issue on a fresh Nova installation:

1. Create a Laravel/Nova Project
2. Create a Model/Table with JSON column
3. Create a Nova Resource for the Model
4. Add a Code field and set the JSON-Option
5. Set '{}' as default value for the Field
6. Browser: open the 'create a new resource' form for the Model in Nova UI

Expected behavior

• Field gets default-value ({}) displayed as content

Observed behavior

• Field gets null displayed as content

Reason

The problem originates in \Laravel\Nova\Fields\Code::resolveAttribute.
When the JSON option is set, the current value is encoded as JSON in line 66/56.
However, encoding null with JSON will result in the string 'null'.

Later in the \Laravel\Nova\Fields\Field::jsonSerialize method, the default value is resolved only if the current value is nullish.
However the string 'null' is not nullish (even though the encoded value is nullish) so the default value will not be resolved.

Workaround

A way to work around this by extending the code field with your own class:

app/Nova/Fields/code.php

<?php

namespace App\Nova\Fields;

use Laravel\Nova\Fields\Field;

class Code extends \Laravel\Nova\Fields\Code
{
    protected function resolveAttribute($resource, $attribute): mixed
    {
        $value = Field::resolveAttribute($resource, $attribute);

        if ($this->json && !is_null($value)) {
            return json_encode($value, $this->jsonOptions ?? JSON_PRETTY_PRINT);
        }

        return $value;
    }
}

In line 20 we ensure the value to encode is not null before serializing it.
However this introduces a problem in scenarios where a null value is expected to be inserted into db in certain cases so use the workaround with caution! ⚠️⚠️⚠️

[crynobone]

Based on my understanding, the observed behavior is expected at the moment and this is a change request.

[davidhemphill]

👋 Hi there! In order to keep this repository focused on bug reports, we auto-close feature requests and requests for help. Feel free to post your feature requests so others can discuss and add reactions. We'll keep an eye on them for later planning.

[jacob418]

Based on my understanding, the observed behavior is expected at the moment and this is a change request.

No, the expected behavior for a call to the default method is not for it to have NO effect without any warnings or notices. This is completely unexpected and leads to misunderstandings.

If this is intended it should be in the docs for the code field with a BIG exclamation mark! Also an alternative is to thrown an exception on use. Just ignoring the problem is no option in my opinion, if it is not taken care of it should be made clear to the developer in some way!

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.