在for循环中，python访问数据库中的下一个对象 [英] python-accessing the next object in database while in for loop

问题描述

这是我的视图代码。我迭代了DB中的所有条目，当rollno匹配时，我想一次存储上一个，当前和下一个学生的学生名称。有没有办法实现？

This is my view code. I iterate over all the entries in DB and when rollno matches, I want to store the student name for previous,current and next student in one go. Is there any way to implement it?

if request.method == 'POST':
        rollno = request.POST.get('roll',None)
        studentlist = Students.objects.all()
        for st in studentlist:
          if st.roll_no == rollno:
             three_students=[*prev_student,current_student,next_student*]

推荐答案

理解你正确的这是你想要的

If I understood you correctly this is what you want

# create generator that will provide you with 3 neighobring students at the same time
def student_gen():
    triple = []    
    for s in Students.objects.all():
        triple.append(s)
        if len(triple) == 3:
            yield triple
            triple.pop(0)


# and inside your view
...
if request.method == 'POST':
    rollno = request.POST.get('roll',None)
    for three_students in student_gen():
        if three_students[1].roll_no == rollno:
            break
    print(three_students)

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