When saving an object(null=True, blank=True) with an empty string __str__ in the admin page.

[Antoliny]

When a field that allows blank and null is used as __str__, an issue occurs when saving the object in the admin page if the value is empty.

TestCase

class Comment(models.Model):
    author = models.CharField(max_length=128, null=True, blank=True)
    content = models.CharField(max_length=128)

    def __str__(self):
        return self.author

When clicking the save-related button, the following error is returned.

Everytime an object is saved in the admin page, a LogEntry is also created. It seems that an issue occurs when LogEntry tries to use the object's __str__.

My guess is that the to_python method in the CharField(Form) performs a strip() process, causing the value entered in the admin page to be "instead of "". As a result, it is treated as None, and an issue occurs when LogEntry tries to use __str__ on that value.