Django:一个模型中的多个通用关系设计不好吗？

Question

我有一个具有多个通用关系的模型,在我的模板中使用它变得非常复杂.该模型是一个'演出'或音乐活动,发生在'Venue'和/或'Festival',并有一个'Musician'和/或'Ensemble'.

复杂的地方是每个'Gig'都有一个演示者,推广者和代理人.这些设置为与其他模型(如"PresenterCompany")的通用关系.演示者公司可以是推广者,演示者或代理人,或者是同一个演出者的所有人.以下是模型(简化为参考):

class Gig(models.Model):
    description = models.CharField(max_length=100, blank=True)
    date = models.DateTimeField()
    venue = models.ForeignKey(Venue)
    festival = models.ForeignKey(Festival, blank = True, null=True)
    musician = models.ManyToManyField(Musician, blank=True)
    ensembles = models.ManyToManyField(Ensemble, blank = True)

    presenter_content_type = models.ForeignKey(ContentType,
        limit_choices_to={"model__in": ("Individual", "ArtsOrganization",'Presenter', "BookingAgent","Festival", "OtherOrganization","PresenterCompany", "Venue")}, related_name = "Presenter Type", verbose_name = "Presenter",blank=True, null=True)
    presenter_id = models.IntegerField(db_index=True, blank=True, null=True, verbose_name='Presenter ID')
    presenter = generic.GenericForeignKey('presenter_content_type','presenter_id')

    promoter_content_type = models.ForeignKey(ContentType,
        limit_choices_to={"model__in": ("Individual", "ArtsOrganization","BookingAgent","Presenter", "Festival", "OtherOrganization","PresenterCompany", "Venue")}, related_name = "promotor", verbose_name='Promoter Type', blank=True, null=True)
    promoter_id = models.IntegerField(db_index=True, blank=True, null=True, verbose_name='Promoter ID')
    promoter = generic.GenericForeignKey('promoter_content_type','promoter_id')

    agent_content_type = models.ForeignKey(ContentType,
        limit_choices_to={"model__in": ("Individual", "BookingAgent")}, related_name="agent", verbose_name='Agent Type', blank=True, null=True)
    agent_id = models.IntegerField(db_index=True, blank=True, null=True, verbose_name='Agent ID')
    agent = generic.GenericForeignKey('agent_content_type','agent_id')


class PresenterCompany(models.Model):
    name = models.CharField(max_length=70)
    address =GenericRelation(Address)
    presented_gig = GenericRelation('Gig',
        content_type_field='presenter_content_type',
        object_id_field='presenter_id',
        related_name='presenter_presented_gig'
    )

    promoted_gig = GenericRelation('Gig',
        content_type_field='promoter_content_type',
        object_id_field='promoter_id',
        related_name='presenter_promoted_gig'
    )
    booked_gig = GenericRelation('Gig',
        content_type_field='promoter_content_type',
        object_id_field='promoter_id',
        related_name='presenter_booked_gig'
    )

主要问题是,当我试图获得演示者公司的所有演出时,我必须为每个角色编写三个不同的for循环,例如{%for presentercompany.presented_gig.all%}中的演出,依此类推......这似乎是多余的代码.

有没有更好的方法来构建这个,例如使用中介模型作为演示者,推广者和代理人？谢谢你的建议!

Answer 1

普通的关系肯定很难处理。我只会在没有其他选择的情况下使用它们。

就你的情况而言，我看到了其他几个选择。您可以在之间建立多对多关系PresenterCompany，并Gig使用直通表来指定关系类型（https://docs.djangoproject.com/en/2.0/topics/db/models/#extra-fields-on-many-to-许多关系）：

class Gig(models.Model):
    description = models.CharField(max_length=100, blank=True)
    date = models.DateTimeField()
    venue = models.ForeignKey(Venue)
    festival = models.ForeignKey(Festival, blank=True, null=True)
    musician = models.ManyToManyField(Musician, blank=True)
    ensembles = models.ManyToManyField(Ensemble, blank=True)


class PresenterCompanyGigRelationship(models.Model):
    gig = models.ForeignKey(Gig, on_delete=models.CASCADE)
    presenter_company = models.ForeignKey(
        'PresenterCompany', on_delete=models.CASCADE)
    relationship = models.CharField(
        max_length=10,
        choices=(
            ('presenter', 'Presenter'),
            ('promoter', 'Promoter'),
            ('agent', 'Agent'),
            ))


class PresenterCompany(models.Model):
    name = models.CharField(max_length=70)
    git = models.ManyToManyField(Gig, through=PresenterCompanyGigRelationship)