Many to many relations have the same value in old and attributes

[peirix]

Describe the bug
Basically the same as #1081 but that got closed, so thought I'd create a new one.

We have an Item class that has a many-to-many relationship to Color through the colors():

public function colors()
{
    return $this->belongsToMany(Color::class, 'item_color');
}

And then our getActivitylogOptions is set up as following:

public function getActivitylogOptions(): LogOptions
{
    return LogOptions::defaults()
        ->logFillable()
        ->logOnly(['colors'])
        ->logOnlyDirty();
}

The first thing is that I can't tell it to log ['colors.id'] which I would like to, I then get an error saying id attribute does not exist on collection. But also the old colors array and the attribute colors array are always the same. And I found that if I sync the colors first the arrays will have the new value, and if I save the item before syncing the colors it will have the old value

$item->save(); // in this log the arrays are both the old colors
$item->colors()->sync($request->input('colors'));
$item->save(); //  in this log the arrays are both the new colors

To Reproduce

Schema::create('items', function (Blueprint $table) {
    $table->id();
    $table->string('name')->nullable();
    $table->softDeletes();
    $table->timestamps();
});
Schema::create('colors', function (Blueprint $table) {
    $table->id();
    $table->string('name');
    $table->string('slug');
    $table->string('hex_code');
    $table->timestamps();
});
Schema::create('item_color', function (Blueprint $table) {
    $table->foreignIdFor(Item::class)->constrained('items')->onUpdate('cascade')->onDelete('cascade');
    $table->foreignIdFor(Color::class)->constrained('colors')->onUpdate('cascade')->onDelete('cascade');

    $table->primary(['item_id', 'color_id']);
});

Expected behavior
First off I would expect the arrays to be different, but I would also like to be able to specify what attribute of the related model I would like to be in the array

Versions (please complete the following information)

• PHP: 8.3
• Database: mysql8
• Laravel: 11.19.0
• Package: 4.8.0

[Jacobs63]

I believe this library is not suited for logging relations due to the nature of the issue.

To log everything properly, you should not only log the colors of an item changing, but also the items of a color changing, meaning inverse relations should also be logged to have a fully working log.

After finding this out, we've decided to ditch this package and instead create a custom logging solution for this.

[peirix]

I think that would be overkill, at least for our use case. I don't want it to log anything if the colors themselves change, I just want to log if an item has changed its colors.

So if an item is set to be blue and black first, and then brown gets added as a color later on, I'd like that to be in the activity log. But since it's a many-to-many relationship the colors attribute isn't set directly on the item and it won't pick it up.

Right now I'm handling it with a batch log, so I manually log any changes to the colors as a separate log, and then when I'm viewing the logs I merge them in the view. It works but feels like an unnecessary workaround.

[Jacobs63]

It's not an unnecessary workaround. The package simply doesn't support such relations.