如何使用外键Django显示来自父模型的数据

Question

我想在查询集中显示子模型数据和父模型数据

这是我在model.py中的模型

class Shareholders(models.Model):
    sharehold_IC = models.CharField(primary_key=True, unique=True, validators=[RegexValidator(r'^\d{12,12}$'), only_int], max_length=12)
    sharehold_name = models.CharField(max_length=100, null=True)
    sharehold_email = models.CharField(max_length=50, null=True, unique=True)
    sharehold_address = models.TextField(null=True, blank=True)
    password = models.CharField(max_length=100)

    def __str__(self):
        return self.sharehold_name

class Meeting(models.Model):

    MEETING_STATUS = (
        ('Coming Soon', 'Coming Soon'),
        ('Live', 'Live'),
        ('Closed', 'Closed')

    )
    meeting_ID = models.CharField(primary_key=True, max_length=6, validators=[RegexValidator(r'^\d{6,6}$')])
    meeting_title = models.CharField(max_length=400, null=True)
    meeting_date = models.DateField()
    meeting_time = models.TimeField()
    meeting_desc = models.CharField(max_length=500, null=True)

    meeting_status = models.CharField(max_length=200, null=True, choices=MEETING_STATUS)
    date_created = models.DateTimeField(default=timezone.now, null=True)
    


    def __str__(self):
        return self.meeting_ID


class Question(models.Model):
    question_ID = models.AutoField(primary_key=True)
    question = models.CharField(max_length=400, null=True)
    meeting_id = models.ForeignKey(Meeting, on_delete=CASCADE)
    shareholder_IC = models.ForeignKey(Shareholders_Meeting, on_delete=CASCADE, related_name='shareholder_ic')
    date_created = models.DateTimeField(default=timezone.now, null=True)


    def __str__(self):
        return str(self.meeting_id)

我尝试显示问题模型中的所有数据，以及股东模型中的股东详细信息，如股东姓名。 这就是我在Views.py中尝试的方法

视图.py

def getMessages(response, meeting_id):
    meeting = Meeting.objects.get(meeting_ID=meeting_id)
    questions = Question.objects.filter(meeting_id=meeting.meeting_ID)
    # print(list(questions.values('shareholder_IC_id')))
    for i in questions:
        print(i.shareholder_ic.all())
    
    return JsonResponse({"questions":list(questions.values())})

但不知怎的，我得到了这个错误。 我想得到这样的结果：

{'question_ID': 141, 'question': "I'm good. How are you?", 'meeting_id_id': '731404', 'shareholder_IC_id': '122311221231', 'date_created': datetime.datetime(2021, 10, 7, 3, 40, 12, 160029, tzinfo=<UTC>), 'sharehold_name':'John Steve', 'sharehold_email':'john@gmail.com'}

如何解决这个问题，或者是否有其他方式显示数据？ 提前谢谢

Answer 1

你必须使用反向关系

questions = Question.shareholder_ic.filter(meeting_id=meeting.meeting_ID)

不要触摸物体

对于其他设置，请在管理器中创建所需的查询集

Answer 2

首先，您没有在Question模型中正确使用related_name属性。它不是使用替代名称来引用相关模型，相反，它是您希望用于引用相关模型中的Question模型的名称，在您的案例中Shareholders。您必须重新制作您的模型：

class Question(models.Model):
    question_ID = models.AutoField(primary_key=True)
    question = models.CharField(max_length=400, null=True)
    meeting_id = models.ForeignKey(Meeting, on_delete=CASCADE)
    shareholder_IC = models.ForeignKey(Shareholders_Meeting, on_delete=CASCADE, related_name='questions')
    date_created = models.DateTimeField(default=timezone.now, null=True)


    def __str__(self):
        return str(self.meeting_id)

然后，在views.py中，需要在Question模型中使用正确的属性名，即shareholders_IC：

def getMessages(request, meeting_id):  # <- Shouldn't the first param be request?
    meeting = Meeting.objects.get(meeting_ID=meeting_id)
    # No need to use meeting.meeting_ID here, you can use the meeting instance
    questions = Question.objects.filter(meeting_id=meeting)
    for i in questions:
        print(i.shareholder_IC)  # <- No .all(), a question has only one shareholder
    
    return JsonResponse({"questions":list(questions.values())})

但是，为了实现您想要的，您应该使用Django REST Framework，或者自己序列化您将获得的不同实例：

def getMessages(request, meeting_id):
    meeting = Meeting.objects.get(meeting_ID=meeting_id)
    questions = Question.objects.filter(meeting_id=meeting)
    questions_list = []
    for i in questions:
        questions_list.append(
            {
                "question_ID": i.question_ID,
                "question": i.question,
                "shareholder_IC_id": i.shareholder_IC.shareholder_IC,
                ...
            }
        )
    
    return JsonResponse(questions_list)

我想推荐两件主要的事情：

1. 了解Django中的关系以及如何在模型中表示它们。例如，在Question中不应该有属性meeting_id。尽管在内部id确实被用于查询Meeting，但属性与模型有关系，而不是与id
2. 使用DRF。这真的会帮你很多忙