https://codereview.stackexchange.com/questions/35516/using-a-csv-file-to-insert-data-into-the-django-model

で知りました。bulk createを使うそう（Django 1.4かららしい）

bulk createを使った場合


    def read_user_data(path):
        with open(path) as f:
            reader = csv.reader(f, delimiter=',')
            _header = next(reader)
            User.objects.bulk_create([User(
                id=row[0],
                hoge=row[1],
            ) for row in reader])

forを使った場合


    def read_user_data(self):
        path = self.user_data_path

        with open(path) as f:
            reader = csv.reader(f)
            _header = next(reader)
            for row in reader:
                _, created = User.objects.get_or_create(
                    id=row[0],
                    hoge=row[1],
                )

こんなModel


from django.db import models

class User(models.Model):
    id = models.PositiveIntegerField(primary_key=True)
    hoge = models.CharField(max_length=128)