Django的多對多場過濾器使用時間創建

Question

我有一個名爲ClassRoom模型，

class ClassRoom(model.Model): 
    class_name = models.CharField(max_lenth=100) 
    students = models.ManyToManyField(User) 

和view.py這樣。

def addstudents(request): 
    class_room = ClassRoom.objects.get(id=1) 
    class_name.students.add(request.user) 

我將學生添加到ClassRoom這樣。 我想列出所有今天加入課堂的學生。 我如何過濾their joining time？

當我們使用django ManyToManyField時，然後Django在數據庫中創建一個額外的表。在該表中包含created時間。我可以使用此字段進行過濾嗎？

Answer 1

您可以使用自定義表（docs here）向M2M關係表中添加額外字段。

class ClassRoom(models.Model): 
    class_name = models.CharField(max_length=100) 
    students = models.ManyToManyField(User, through='ClassMate') 


class ClassMate(models.Model): 
    class_room = models.ForeignKey(ClassRoom, on_delete=models.CASCADE) 
    user = model.ForeignKey(User, on_delete=models.CASCADE) 
    date_joined = models.DateField(auto_now_add=True) 

然後，你可以這樣做：

class_room = ClassRoom.objects.get(...) 

class_room.students.filter(date_joined=datetime.today()) 

請記住，（如文檔說）現在你必須實例ClassMate對象添加一個關係：

class_room = ClassRoom.objects.get(...) 
user = request.user 
class_mate = ClassMate(class_room=class_room, user=user) 
class_mate.save()