django: admin.StackedInline show full name instead of user name

my inline:

class CollaboratorInLine(admin.StackedInline):
    model = Collaborator
    extra = 0

my model:

class Collaborator(models.Model):
    report = models.ForeignKey(Report)
    collaborator = models.ForeignKey(User, limit_choices_to={'groups__name':u'team1'})
    def reutnName(self):
        return self.collaborator.get_full_name()

    def __unicode__(self):
        return self.collaborator.get_full_name()

The inline collaborator is shown as a drop downlist, and the ppl are shown as usernames intead of full names. does anyone know how to change it to full name开发者_StackOverflow?

thanks

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i got it using formfield_for_manytomany and formfield_for_foreignkey i thought they could only be used in modeladmin, but it could also be used for StackedInline :)