Encrypted Array Won't Save in Eloquent Model - laravel

Question

I'm having an odd error with saving an encrypted array in Laravel. The model never updates even when save() is called.
There are no console or SQL errors.
When the encryption is disabled, there are no errors and the model updates successfully.
In a Controller, I'm calling the model like so:
$userData = UserData::where('user_id', $user_id)->first();
I then pull the array:
$encryptedData = $userData->app_data;
And I want to add to this array e.g.
$encryptedData['new'] = 'axy';
$encryptedData['time'] = time();
I then update the model and save it:
$userData->app_data = $encryptedData;
$userData->save();
However, here is where the problem starts. The model does not update. It remains as if nothing happens. Hence if I refresh(), I get the same data as if I had never added the two new entries. When I log it, it looks like this:
Array
(
[token] => xyz
[access_token] => abc
)
After the addition of two new entries:
Array
(
[token] => xyz
[access_token] => abc
[new] => 'axy'
[time] => 1234
)
And after the save() and refresh():
Array
(
[token] => xyz
[access_token] => abc
)
The model looks like this:
namespace App;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\Crypt;
use Illuminate\Contracts\Encryption\DecryptException;
class UserData extends Model
{
protected $fillable = [
'user_id', 'app_data'
];
protected $casts = [
'user_id' => 'int',
'app_data' => 'array'
];
public function getAppDataAttribute($value)
{
try {
return decrypt($value);
}
catch (DecryptException $e) {
return $value;
}
}
public function setAppDataAttribute($value)
{
$this->attributes['app_data'] = encrypt($value);
}
}
Why are my additions to the array not being saved?
Edit: The strangeness continues
If I call:
UserData::where('id', $userData->id)->update(['app_data' => $encryptedData]);
Then the model does update and does not encrypt, HOWEVER, when I refresh and log the new 'app_data' field, it is returned as a JSON string and not an array as before. I need to cast/decode it to an array each time I want to use it.

Answer 1

Couple of things to look for.
1) The Laravel encrypter uses the app key. Make sure you have one in your .env file. If not, run php artisan key:generate
2) I assume the array is correctly formatted like this:
Array
(
'token' => 'xyz', // You have a = here and no commas after any other value
'access_token' => 'abc'
)
3) Depending on what you are storing this as, you can test by serializing the array before encrypting it:
$arr = serialize($encryptedData); // After you have added new data to the array
$userData->app_data = $arr;
$userData->save();
This is automatic in Laravel, but may give you a help hunting the bug. Test with your mutator using encryptString() and manually unserialize / decryptString() to see if any odd behavior by stepping through the values as they are mutated.