如何设置django中manytomany字段的初始值?

我正在使用ModelForm创建表单,并且我已经为表单中的每个字段设置了初始值,除了一个多字段。

我知道我需要给它一个清单,但我不能让它工作。我现在看到的代码是:

        userProfile = request.user.get_profile()
        employer = userProfile.employer
        bar_memberships = userProfile.barmembership.all()
        profileForm = ProfileForm(
            initial = {'employer': employer, 'barmembership' : bar_memberships})

但那不管用。我是不是错过了什么?

根据评论中的要求,以下是我的模型的相关部分:

# a class where bar memberships are held and handled.
class BarMembership(models.Model):
    barMembershipUUID = models.AutoField("a unique ID for each bar membership",
        primary_key=True)
    barMembership = USStateField("the two letter state abbreviation of a bar membership")

    def __unicode__(self):
        return self.get_barMembership_display()

    class Meta:
        verbose_name = "bar membership"
        db_table = "BarMembership"
        ordering = ["barMembership"]

以及正在扩展的用户配置文件:

# a class to extend the User class with the fields we need.
class UserProfile(models.Model):
    userProfileUUID = models.AutoField("a unique ID for each user profile",
        primary_key=True)
    user = models.ForeignKey(User,
        verbose_name="the user this model extends",
        unique=True)
    employer = models.CharField("the user's employer",
        max_length=100,
        blank=True)
    barmembership = models.ManyToManyField(BarMembership,
        verbose_name="the bar memberships held by the user",
        blank=True,
        null=True)

希望这有帮助。