所以我在django中有这两个模型:
class Course(models.Model):
def get_image_path(self, filename):
return os.path.join('courses', str(self.slug), filename)
def __str__(self):
return self.name
def save(self, *args, **kwargs):
self.slug = slugify(self.name)
super(Course, self).save(*args, **kwargs)
name = models.CharField(max_length=255, verbose_name="Nombre")
description = models.CharField(max_length=255, verbose_name="Descripción")
price = models.DecimalField(max_digits=12,decimal_places=2, verbose_name="Precio")
slug = models.SlugField(blank=True, max_length=255)
icon_img = models.ImageField(upload_to=get_image_path, blank=True, null=True, verbose_name="Imagen")
background_color = ColorField(default="#026085")
class Meta:
verbose_name = "curso"
verbose_name_plural = "cursos"
class UserCourse(models.Model):
user = models.ForeignKey(User)
course = models.ForeignKey(Course)
因此,每当用户“购买”课程时,它都会存储在UserCourse中。我有一个视图,系统显示用户购买的所有课程的列表。这是视图代码:
def user_course_list_view(request, username):
context_dict = {}
try:
user_courses = UserCourse.objects.filter(user=request.user).course_set
context_dict['courses'] = user_courses
context_dict['heading'] = "Mis cursos"
except:
context_dict['courses'] = None
context_dict['heading'] = "Mis cursos wey"
return render(request, 'courses/course_list.html', context=context_dict)
我不知道错误在哪里,我似乎无法捕获异常(我使用django和docker)
答案 0 :(得分:2)
这样的事情应该有效。
usercourse_objects = UserCourse.objects.filter(user=request.user).select_related('course')
user_courses = [x.course for x in usercourse_objects]
有多种方法可以做到这一点,但一种方法是先为当前用户获取所有UserCourse
个对象:
usercourse_objects = UserCourse.objects.filter(user=request.user)
然后,对于每个UserCourse
对象,获取相关的Course
:
user_courses = [x.course for x in usercourse_objects]
现在,第二行导致N个数据库查询(每次我们遵循course
外键关系时一个。为了防止这种情况,第一行可以更改为:
usercourse_objects = UserCourse.objects.filter(user=request.user).select_related('course')
这会预先填充UserCourse对象的course
属性。有关select_related()
的更多信息,请访问here。