Django:一个模型中是否存在多个通用关系设计错误？

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。该模型是在“地点”和/或“节日”发生的“演出”或音乐事件，并具有“音乐家”和/或“合奏”。

变得复杂的是，每个“演出”都有主持人，发起人和代理人。这些设置为与其他模型(如“PresenterCompany”)的通用关系。演示者公司可以是发起人，演示者或代理，也可以是同一演唱会的所有人。这是模型(简化为引用):

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，当我尝试获取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，即{presentercompany.presented_gig.all％}中的演出的％，依此类推...这似乎是多余的代码。

有没有更好的方法来构造这种结构，例如对演示者，发起者和代理使用中间模型？谢谢你的建议!

最佳答案

通用关系肯定很难处理。我只会在没有其他选择的情况下使用它们。

就您而言，我看到了其他两个选择。您可以使用穿透表指定关系的类型(https://docs.djangoproject.com/en/2.0/topics/db/models/#extra-fields-on-many-to-many-relationships)，在PresenterCompany和Gig之间建立ManyToMany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)

关于Django:一个模型中是否存在多个通用关系设计错误？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/17688352/