class ContentType(models.Model):
    app_label = models.CharField(max_length=100)
    model = models.CharField(_(‘python model class name‘), max_length=100)
    objects = ContentTypeManager()

    class Meta:
        verbose_name = _(‘content type‘)
        verbose_name_plural = _(‘content types‘)
        db_table = ‘django_content_type‘
        unique_together = ((‘app_label‘, ‘model‘),)

    def __str__(self):
        return self.name

    @property
    def name(self):
        model = self.model_class()
        if not model:
            return self.model
        return force_text(model._meta.verbose_name)

    def model_class(self):
        "Returns the Python model class for this type of content."
        try:
            return apps.get_model(self.app_label, self.model)
        except LookupError:
            return None

    def get_object_for_this_type(self, **kwargs):
        """
        Returns an object of this type for the keyword arguments given.
        Basically, this is a proxy around this object_type‘s get_object() model
        method. The ObjectNotExist exception, if thrown, will not be caught,
        so code that calls this method should catch it.
        """
        return self.model_class()._base_manager.using(self._state.db).get(**kwargs)

    def get_all_objects_for_this_type(self, **kwargs):
        """
        Returns all objects of this type for the keyword arguments given.
        """
        return self.model_class()._base_manager.using(self._state.db).filter(**kwargs)

    def natural_key(self):
        return (self.app_label, self.model)

from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
from django.contrib.contenttypes.models import ContentType
class Survery(models.Model):
    """
    问卷
    ID        name            by_class      creator
    1    第一次班级调查      三年级五班     李老师
    """
    name = models.CharField(verbose_name="调查问卷名称", max_length=128, unique=True)
    by_class = models.ForeignKey(verbose_name="问卷调查班级", to="ClassList")
    date = models.DateTimeField(verbose_name="问卷创建日期", auto_now_add=True)
    creator = models.ForeignKey(verbose_name="创建者", to="UserInfo")


class SurveryItem(models.Model):
    """
    问卷题目
    ID                 survery                       name                   date          answer_type
     1    1(代表上面创建的第一次班级调查)      您最喜欢吃什么水果?       xxx-xxx-xx           1
     1    1(代表上面创建的第一次班级调查)      您最喜欢什么玩具?         xxx-xxx-xx           2
     1    1(代表上面创建的第一次班级调查)      您最喜欢什么英雄人物?     xxx-xxx-xx           3
    """
    survery = models.ForeignKey(verbose_name=‘问卷‘, to=‘Survery‘)
    name = models.CharField(verbose_name="调查问题", max_length=255)
    date = models.DateField(auto_now_add=True)
    answer_type_choices = (
        (1, "打分(1~10分)"),
        (2, "单选"),
        (3, "建议"),
    )
    answer_type = models.IntegerField(verbose_name="问题类型", choices=answer_type_choices, default=1)


class SurveryChoices(models.Model):
    """
    问卷选项答案(针对选项类型)
    ID    item    content   points
    1       2       A         10分
    1       2       B         9分
    1       2       C         8分
    1       2       D         7分
    """
    item = models.ForeignKey(verbose_name=‘问题‘, to=‘SurveryItem‘)
    content = models.CharField(verbose_name=‘内容‘, max_length=256)
    points = models.IntegerField(verbose_name=‘分值‘)
    surveryrecord = GenericRelation("SurveryRecord")


class Score(models.Model):
    item = models.ForeignKey(verbose_name=‘问题‘, to=‘SurveryItem‘)
    points = models.IntegerField(verbose_name=‘分值‘)
    surveryrecord = GenericRelation("SurveryRecord")


class Suggestion(models.Model):
    item = models.ForeignKey(verbose_name=‘问题‘, to=‘SurveryItem‘)
    suggests = content = models.CharField(verbose_name=‘内容‘, max_length=256)
    surveryrecord = GenericRelation("SurveryRecord")


class SurveryRecord(models.Model):
    """
    问卷记录
    ID    survery      student_name   survery_item  content_type  object_id  
    1        1            1               1              1             1
    1        1            1               2              1              2
    1        1            1               3              1               3
    """
    survery = models.ForeignKey(Survery, verbose_name="问卷")
    student_name = models.ForeignKey(verbose_name="学员姓名", to="Student")
    survery_item = models.ForeignKey(verbose_name="调查项", to=‘SurveryItem‘)

    content_type = models.ForeignKey(ContentType, blank=True, null=True)
    object_id = models.PositiveIntegerField(blank=True, null=True)
    content_object = GenericForeignKey(‘content_type‘, ‘object_id‘) # 這个字段不会再数据库中存在,只是在查询时有用

    date = models.DateTimeField(verbose_name="答题日期", auto_now_add=True) 

from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
from django.contrib.contenttypes.models import ContentType

# Create your models here.

class DegreeCourse(models.Model):
    """学位课程
     ID    名称
     1    学位课1
     2    学位课2

    """
    name = models.CharField(max_length=128, unique=True)

    x1 = GenericRelation("Coupon")

class Course(models.Model):
    """课程
     ID    名称
     1    普通课1
     2    普通课2
    """
    name = models.CharField(max_length=128, unique=True)

class Coupon(models.Model):
    """优惠券生成规则

    ID     优惠券名称         content_type_id(表)         object_id（表中数据ID）
     1       通用                 null                    null
     2       满100-10               8                      1
     3       满200-30               8                      2
     4       满200-30               9                      1
    总结：
    """
    name = models.CharField(max_length=64, verbose_name="活动名称")
    brief = models.TextField(blank=True, null=True, verbose_name="优惠券介绍")

    # 给你的model设置一个 ForeignKey 字段到ContentType. 一般命名为“content_type”.用来放想要关联的那个表在contenttype表中的id
    content_type = models.ForeignKey(ContentType, blank=True, null=True)
    # 对象ID，用来储存你想要关联的model主键值，对于大多数model,，这是一个 PositiveIntegerField字段。并且通常命名为 “object_id”.
    object_id = models.PositiveIntegerField("绑定课程", blank=True, null=True, help_text="可以把优惠券跟课程绑定")

    content_object = GenericForeignKey(‘content_type‘, ‘object_id‘)

from django.shortcuts import render,HttpResponse
from django.contrib.contenttypes.models import ContentType
def test(request):



    content = ContentType.objects.get(app_label=‘app01‘,model=‘coupon‘)
    model_class = content.model_class()
    print(content)  # coupon
    print(model_class)  # <class ‘app01.models.Coupon‘>
    print(model_class.objects.all())    #<QuerySet [<Coupon: 通用>, <Coupon: 满100-10>, <Coupon: 满200-30>, <Coupon: 满200-30>]>


    # 给学位课1或普通课创建优惠券
    # d1 = models.DegreeCourse.objects.get(id=1)
    # models.Coupon.objects.create(name=‘优惠券‘, brief=‘2000-30‘, content_object=d1)

    # d1 = models.Course.objects.get(id=1)
    # models.Coupon.objects.create(name=‘优惠券‘, brief=‘100-90‘, content_object=d1)
    #或 models.Coupon.objects.create(name=‘优惠券‘, brief=‘100-90‘, content_object_id=1)

    # 当前优惠券，绑定的课程？
    # obj = models.Coupon.objects.get(id=2)
    # print(obj.content_object)   #普通课1
    ‘‘‘通过content_object直接找到与其关联的models对象‘‘‘
    #正向查找：models对象.content_object得到的是models对象



    # 当前课程，都有哪些优惠券？
    # obj = models.DegreeCourse.objects.get(id=1)
    # print(obj.x1.all()) # [<Coupon: 满200-30>]>
    # v = models.DegreeCourse.objects.values(‘name‘,‘x1__brief‘)
    # print(v)    # <QuerySet [{‘name‘: ‘学位课1‘, ‘x1__brief‘: ‘‘}, {‘name‘: ‘学位课2‘, ‘x1__brief‘: None}]>

    # 反向查找：models对象.反向关联字段.all() 得到的是QuerySet对象

    return HttpResponse(‘...‘)