Sometimes, you may end up with a collection that contains null values.

Removing those null values from the collection can be done very smoothly with the filter method.

When you look at the source code of the filter method in the Illuminate\Support\Collection class, you will see that $callback is an optional parameter:

public function filter(callable $callback = null)
{
    if ($callback) {
        return new static(Arr::where($this->items, $callback));
    }

    return new static(array_filter($this->items));
}

When no callback is provided, array_filter will be executed, also without a callback.

The PHP Manual states that:

If no callback is supplied, all empty entries of the array will be removed.

Values that are false or null are considered empty. This means you can just call filter without arguments:

$collection = collect([1, 2, null, 4, null, null, 7]);

$collection->filter();

// [1, 2, 4, 7]

All null values will be removed from the collection.