HasAttributes::hasChanges null attributes parameter detection

[eidng8]

• Laravel Version: 5.6.17
• PHP Version: 7.1

Description:

The hasChanges() method checks for empty $attributes at entrance.

        // If no specific attributes were provided, we will just see if the dirty array
        // already contains any attributes. If it does we will just return that this
        // count is greater than zero. Else, we need to check specific attributes.
        if (empty($attributes)) {
            return count($changes) > 0;
        }

However, functions like isDirty() and wasChanged() calls the method like these:

    public function isDirty($attributes = null)
    {
        return $this->hasChanges(
            $this->getDirty(), is_array($attributes) ? $attributes : func_get_args()
        );
    }

    public function wasChanged($attributes = null)
    {
        return $this->hasChanges(
            $this->getChanges(), is_array($attributes) ? $attributes : func_get_args()
        );
    }

When called through isDirty() like $this->isDirty(null);, hasChanges() receives the $attributes parameter as an array of [null] due to is_array($attributes) ? $attributes : func_get_args(). Which in turn skips right through the empty check and returns a faulty false.

Steps To Reproduce:

Just call $this->isDirty(null); on any modified model instance.

[staudenmeir]

I'll fix it.

[Miguel-Serejo]

What is there to fix here? Calling isDirty(null) is asking "Is the null property of my Model dirty?" to which the answer should always be "No, because it doesn't exist".

What's your use case for calling isDirty(null)?

[staudenmeir]

Since the default value of the $attributes parameter is NULL, explicitly calling isDirty(null) should work:

$model->isDirty($if ? ['foo'] : null);

[Miguel-Serejo]

If anything, that's an argument for changing the default to [] rather than null just to avoid people thinking null is a valid parameter value.

[staudenmeir]

The result of isDirty([]) on a modified model was (accidentally) changed in #20130. Before, it returned false, now it returns true. So originally null was different from [].