如何将实例传递给视图？答案

【问题标题】：How do I pass an instance to a view?如何将实例传递给视图？
【发布时间】：2021-04-26 06:55:18
【问题描述】：

我无法理解系统正在返回的投诉。这是系统的视图

 def AddMarksView(request):
        class_name = request.session.get('class_name')
        subject = Subject.objects.filter(name='Maths')
        exam = Exam.objects.filter(name='Endterm')
        students =  Students.objects.filter(school=request.user.school,klass__name = class_name,stream__name='South')
        if request.method == 'POST':
            for student in students:
                marks = int(request.POST['marks'])
                marks_object = Marks.objects.create(student=student,marks=marks,subject=subject,exam=exam)
        else:
            return render(request,'feed_marks.html')
        return redirect('search_m')

返回的错误是

Cannot assign "<QuerySet [<Exam: Endterm>]>": "Marks.exam" must be a "Exam" instance.

Marks odel 的模型是

class Marks(models.Model):
    exam = models.ForeignKey(Exam,on_delete=models.SET_NULL,null=True,blank=True)
    subject = models.ForeignKey(Subject,on_delete=models.SET_NULL,null=True,blank=True)
    student = models.ForeignKey(Students,on_delete=models.SET_NULL,null=True,blank=True)
    marks = models.IntegerField(validators=[MinValueValidator(0), MaxValueValidator(100),] ,null=True,blank=True)

如何格式化视图以使其不返回错误？

【问题讨论】：

标签： python-3.x django django-views

【解决方案1】：

尝试获取而不是过滤器，以便您的代码读取。

def AddMarksView(request):
        class_name = request.session.get('class_name')
        subject = Subject.objects.get(name='Maths')
        exam = Exam.objects.get(name='Endterm')
        students =  Students.objects.filter(school=request.user.school,klass__name = class_name,stream__name='South')
        if request.method == 'POST':
            for student in students:
                marks = int(request.POST['marks'])
                marks_object = Marks.objects.create(student=student,marks=marks,subject=subject,exam=exam)
        else:
            return render(request,'feed_marks.html')
        return redirect('search_m')

【讨论】：