Creating mptt from a django model

Question

I have a django model as follows: (it has both the mptt and the regular model)

from django.db import models
from mptt.models import MPTTModel, TreeForeignKey

class deg_course_cat(models.Model):
    degree_code = models.CharField(max_length=24)
    specialization = models.CharField(max_length=48)
    category_level1 = models.CharField(max_length=48)
    category_level2 = models.CharField(max_length=96)
    category_level3 = models.CharField(max_length=48)
    min_credit = models.IntegerField()
    max_credit = models.IntegerField()
    primarystuff = models.CharField(max_length=24)

class deg_course_cat_mptt(MPTTModel):
    name = models.CharField(max_length=100, unique=False)
    min_credit = models.IntegerField(null=True)
    max_credit = models.IntegerField(null=True)
    parent = TreeForeignKey('self', null=True, blank=True, related_name='children')

    class MPTTMeta:
        order_insertion_by = ['name']

# Create your models here.

I have a python code written to get all the data of the django model and create an mptt model from it automatically. The python code looks like this:

from studentapp.models import deg_course_cat, deg_course_cat_mptt

degreeroot = deg_course_cat_mptt.objects.create(name="DegreeRoot")

for degrees in deg_course_cat.objects.values_list('degree_code', flat=True):
    degreearray = list(set(deg_course_cat.objects.values_list('degree_code', flat=True)))
    for i in range(0,len(degreearray)):
    degree = []
        degree.append(deg_course_cat_mptt.objects.create(name= degreearray[i], parent=degreeroot))

        for categories_l1 in deg_course_cat.objects.values_list('category_level1', flat=True):
        category_l1_array = list(set(deg_course_cat.objects.filter(degree_code=degree[i]).values_list('category_level1', flat=True)))
        for j in range(0,len(category_l1_array)):
        categorylevel1 = []
            categorylevel1.append(deg_course_cat_mptt.objects.create(name= category_l1_array[j], parent=degree[i]))

I am getting the following error :

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/abhishek/projects/studentmptt/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 399, in execute_from_command_line
    utility.execute()
  File "/home/abhishek/projects/studentmptt/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/abhishek/projects/studentmptt/local/lib/python2.7/site-packages/django/core/management/base.py", line 242, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/abhishek/projects/studentmptt/local/lib/python2.7/site-packages/django/core/management/base.py", line 285, in execute
    output = self.handle(*args, **options)
  File "/home/abhishek/projects/studentmptt/local/lib/python2.7/site-packages/django/core/management/base.py", line 415, in handle
    return self.handle_noargs(**options)
  File "/home/abhishek/projects/studentmptt/local/lib/python2.7/site-packages/django/core/management/commands/shell.py", line 83, in handle_noargs
    import code
  File "/home/abhishek/projects/studentmptt/studentsite/code.py", line 12, in <module>
    category_l1_array = list(set(deg_course_cat.objects.filter(degree_code=degree[i]).values_list('category_level1', flat=True)))
IndexError: list index out of range

Answer 1

In your error statement

category_l1_array = list(set(deg_course_cat.objects.filter(degree_code=degree[i]).values_list('category_level1', flat=True)))

It is clear that variable degree doesn't have any value at index i. That's why it give Indexerror:list index out of range.

You can debug problem by using import pdb;pdb.set_trace() statement before error line.