Using dynamic object filter

Question

I am trying to access names of all the students having marks 100.

def get_names(request):
    students = Result.objects.filter(marks=100)
    student_name = []
    for x in students:
        student_name.append(x.student)
    for x in student_name:
        print (x.name)
    return render(request, 'exam/index.html', {'names': student_name})

When I run this view, 'Student has no attribute '__getitem__'' is displayed on the line print(x.name). I read something about dynamic object filter but cannot figure it out in this case.

Model structure

class Student(models.Model):
    name = models.CharField(max_length=20)
    stream = models.CharField(max_length=20)


class Result(models.Model):
    student = models.ForeignKey(Student, on_delete=models.CASCADE)
    marks = models.IntegerField()

Paulo Almeida · Accepted Answer · 2017-08-24 20:07:30Z

You would be helping yourself if you used more informative variable names, instead of seemingly going out of your way to come up with confusing ones. In your code snippet:

def get_names(request):
    results = Result.objects.filter(marks=100)
    students = []
    for result in results:
        students.append(result.student)
    for student in students:
        print(student.name)
    return render(request, 'exam/index.html', {'names': student_name})

That said, I don't understand where your Student has no attribute '__getitem__' is coming from, or why it is being printed and not raising an exception. __getitem__ is for accessing items of sequences with integer or slice keys, and you don't seem to be doing that anywhere. From the models you presented here, x (or student in my code) should be a Student instance, and doing print(x.name) should work.

In any case, you could do this in a much simpler way:

def get_names(request)
    students = Student.objects.filter(result__marks=100).distinct()
    return render(request, 'exam/index.html', {'students': students})

Then you can iterate students in the template and acess student.name. If you just want to pass a list of names to the template, you could use values_list('name', flat=True) in the query.

It worked. Thanks! I'll modify the variable names. Thanks for the suggestion

Dharmesh Fumakiya · Accepted Answer · 2017-08-24 19:22:07Z

0

If you want to just print the student name

for x in students:
    print(x.student.name)
    student_name.append(x.student)

answered Aug 24, 2017 at 19:22

Dharmesh Fumakiya

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1 Comment

rohit1248 Over a year ago

My main objective is to pass the list of names to a web page. But when the above mentioned error occurred, I added few extra lines to print the list on Python console.

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