Custom datetime casting works, but not if you define custom format

[apeisa]

Thanks to #2653 casting works now, but not in all cases. When using date casts, you can also define the format in the string format, like this (docs):

   protected $casts = [
        'mydate' => 'datetime:j.n.Y H:i',
    ];

When using cast like that, it doesn't work. Without formatting set, it does work as expected:

   protected $casts = [
        'mydate' => 'datetime',
    ];

Here is simple class that can be used for testing:

<?php

namespace App\Models;

use Carbon\Carbon;
use MongoDB\Laravel\Eloquent\Model;

class Car extends Model
{
    protected $guarded = [];

    protected $casts = [
        'sold_at' => 'datetime:j.n.Y H:i',
    ];

    public function sell()
    {
        $this->sold_at = Carbon::now();
        $this->save();
        return $this;
    }
}

And to test this run these commands on Tinker:

> $car = App\Models\Car::create();
= App\Models\Car {#8065
    updated_at: MongoDB\BSON\UTCDateTime {#8071
      +"milliseconds": "1698741994126",
    },
    created_at: MongoDB\BSON\UTCDateTime {#8071},
    _id: MongoDB\BSON\ObjectId {#8075
      +"oid": "6540beea13e41d27cd036b52",
    },
  }

> $car->sell();
= App\Models\Car {#8065
    updated_at: MongoDB\BSON\UTCDateTime {#8063
      +"milliseconds": "1698742000466",
    },
    created_at: MongoDB\BSON\UTCDateTime {#8071
      +"milliseconds": "1698741994126",
    },
    _id: MongoDB\BSON\ObjectId {#8075
      +"oid": "6540beea13e41d27cd036b52",
    },
    sold_at: Illuminate\Support\Carbon @1698742000 {#8066
      date: 2023-10-31 08:46:40.461974 UTC (+00:00),
    },
  }

As you can see the sold_at has Carbon object in database, it should be MongoDB\BSON\UTCDateTime. If you remove the :j.n.Y H:i part from $casts then it works as expected. Here is tinker output without the date formatting:

App\Models\Car {#8065
    updated_at: MongoDB\BSON\UTCDateTime {#8063
      +"milliseconds": "1698742105625",
    },
    created_at: MongoDB\BSON\UTCDateTime {#8071
      +"milliseconds": "1698742103464",
    },
    _id: MongoDB\BSON\ObjectId {#8075
      +"oid": "6540bf576b0d0e380a0cd942",
    },
    sold_at: MongoDB\BSON\UTCDateTime {#8078
      +"milliseconds": "1698742105624",
    },
  }

Originally posted by @apeisa in #2653 (comment)