我需要在django上运行一个查询，但我无法生成算法

Question

Django 中有这些模型

class Course(models.Model):
Title = models.CharField(max_length=200, unique=True)
Card_Title = models.CharField(max_length=200, default='Nothing')
Description = RichTextField(blank=True, null=True)
Course_Image = models.FileField(upload_to='CoursesImages')
Progress = models.IntegerField(blank=True, null=True)
date = models.DateField(default=timezone.now, blank=True)
def __str__(self):
return self.Title

class Lesson(models.Model):
Course_id = models.ForeignKey(Course, on_delete=models.CASCADE)
Number = models.IntegerField()
Title = models.CharField(max_length=200)
Completed = models.BooleanField(default=False, blank=True)
date = models.DateField(default=timezone.now, blank=True)
def __str__(self):
return self.Title + ' (' + str(self.Number) + ')'

class Topic(models.Model):
Title = models.CharField(max_length=100)
Topic = models.FileField()
Lesson = models.ForeignKey(Lesson, on_delete=models.CASCADE)
Completed = models.BooleanField(default=False, blank=True)
date = models.DateField(default=timezone.now, blank=True)
def __str__(self):
return self.Title

工作原理：

• 每节课都有一门课
• 所以我们在一门课上有很多课
• 一个主题可以有一节课
• 所以我们在一节课上有很多主题

我需要弄清楚为什么查询是这样的：

{'Lesson1':[Topic1,Topic2,Topic,3,Topic,4],'Lesson':[Topic1,Topic2,Topic,3,Topic,4],........}

课程ID、相关课程和主题必须提取

Answer 1

ans = {}
lessons = course.lesson_set
for lesson in lessions:
ans[lession.title] = lesson.topic_set