在Django模型中没有生成QR码

Question

我目前正在尝试为我的Django模型中的员工档案生成QR码。我正在关注此网站的教程：https://gilang.chandrasa.com/generate-qr-code-in-django-model/ 但不幸的是，当我创建个人资料时，没有生成QR码。

注意：我正在使用qr-code 5.3而不是5.1，如教程所示。

models.py

from django.db import models
from django.conf import settings
from django.core.urlresolvers import reverse
from django.core.files.uploadedfile import InMemoryUploadedFile

import random, qrcode
from io import StringIO


def upload_location(instance, filename):
    return '%s/profile_images/%s/' % (instance.user.username, filename)


def qrcode_location(instance, filename):
    return '%s/qr_codes/%s/' % (instance.user.username, filename)


# Create your models here.
class EmployeeProfile(models.Model):
    user = models.ForeignKey(settings.AUTH_USER_MODEL,  on_delete=models.CASCADE)
    image = models.ImageField(upload_to=upload_location,
                          null=True,
                          blank=True,
                          width_field='width',
                          height_field='height'
                          )
    qrcode = models.ImageField(upload_to=qrcode_location, null=True, blank=True)
    height = models.IntegerField(default=0)
    width = models.IntegerField(default=0)
    first_name = models.CharField(max_length=30)
    middle_name = models.CharField(max_length=30, null=True, blank=True)
    last_name = models.CharField(max_length=30)
    phone_number = models.CharField(max_length=12)
    email = models.CharField(max_length=254, unique=True)
    address_line1 = models.CharField(max_length=60)
    address_line2 = models.CharField(max_length=20, null=True, blank=True)
    city = models.CharField(max_length=60)
    state = models.CharField(max_length=2)
    employee_id = models.CharField(unique=True, max_length=11)
    hire_date = models.CharField(max_length=19, null=True, blank=True)
    last_screen = models.CharField(max_length=19, null=True, blank=True)
    active = models.CharField(max_length=3, default='yes')

    def __str__(self):
        return self.first_name

    """
    Check to see if an image is provided, if not then use a default profile pic
    """
    def image_url(self):
        if self.image:
            return self.image.url
        else:
            return '/static/images/default-profile-pic.jpg'

    def save(self):
        first_initial = self.first_name[0].upper()
        second_initial = self.last_name[0].upper()
        id_number = first_initial + second_initial + str(random.randint(1000000, 9999999))

        if not EmployeeProfile.objects.filter(employee_id=id_number).exists():
            self.employee_id = id_number
            super(EmployeeProfile, self).save()

    def generate_qrcode(self):
        qr = qrcode.QRCode(
            version=1,
            error_correction=qrcode.constants.ERROR_CORRECT_L,
            box_size=10,
            border=4,
        )
        qr.add_data(reverse('ppm:view-profile', kwargs={'pk': self.id}))
        qr.make(fit=True)

        img = qr.make_image()

        buffer = StringIO()
        img.save(buffer)
        filename = 'qrcode-%s.png' & self.id
        filebuffer = InMemoryUploadedFile(
            buffer, None, filename, 'image/png', buffer.len, None
        )
        self.qrcode.save(filename, filebuffer)

任何想法我可能做错了什么？

--------------------- SOLUTION UPDATE --------------------- ----

在玩了一些代码后，我终于想出了如何生成qr代码：

def save(self):
    first_initial = self.first_name[0].upper()
    second_initial = self.last_name[0].upper()
    id_number = first_initial + second_initial + str(random.randint(1000000, 9999999))
    self.generate_qrcode()

    if not EmployeeProfile.objects.filter(employee_id=id_number).exists():
        self.employee_id = id_number
        super(EmployeeProfile, self).save()



def generate_qrcode(self):
    qr = qrcode.QRCode(
        version=1,
        error_correction=qrcode.constants.ERROR_CORRECT_L,
        box_size=10,
        border=4,
    )
    qr.add_data('Some data')
    qr.make(fit=True)

    filename = 'qrcode-code1.png'

    img = qr.make_image()
    img.save('media_cdn/' + qrcode_location(self, filename))