NotperlyConfigured：导入后端时出错

Question

在我的设置文件中，我定义为

SHOP_ADDRESS_MODEL = 'app.accounts.models.Address'
SHOP_PRODUCT_MODEL = 'app.products.models.Product'

但我得到这样的错误

ImproperlyConfigured: Error importing backend app.products.models: "cannot import name AddressModel". Check your SHOP_PRODUCT_MODEL settings

当我使用python manage.py runserver运行应用程序时，它运行正常。但是我在使用gunicorn运行时遇到此错误。我在gunicorn配置中包含了virtualenv路径

产品/ models.py

from decimal import Decimal, InvalidOperation

from django.db import models
from django.contrib import admin
from django.conf import settings

from shop.models_bases import BaseProduct
from app.utils import is_foreign

from haystack import indexes

def safewrite(s):
    try:
        with open("foreigntest.txt",'a') as f:
            f.write(s)
            f.write('\n')
    except:
        print "(error)"
        print s

class Product(BaseProduct, indexes.Indexable):
    # General fields
    part_number = models.CharField(max_length=255)
    category = models.CharField(max_length=255, blank=True, null=True)
    summary = models.TextField(blank=True, null=True)

    def get_price(self, request=None):
        safewrite("get_price() REQUEST")
        if is_foreign(request):
            safewrite("FOREIGN")
            try:
                return Decimal(self.curr_intl_base_price_a_stored)
            except InvalidOperation:
                return Decimal(0)
        else:
            safewrite("NO")
            try:
                return Decimal(self.curr_domestic_base_price_a_stored)
            except InvalidOperation:
                return Decimal(0)

    def get_price_b(self, request=None):
        safewrite("get_price_b() REQUEST")
        if is_foreign(request):
            safewrite("FOREIGN")
            try:
                return Decimal(self.curr_intl_base_price_b_stored)
            except InvalidOperation:
                return Decimal(0)
        else:
            safewrite("NO")
            try:
                return Decimal(self.curr_domestic_base_price_b_stored)
            except InvalidOperation:
                return Decimal(0)

    # webmfg fields:
    AM_Number = models.CharField(max_length=255, blank=True, null=True)
    Angle_of_Incidence = models.CharField(max_length=255, blank=True, null=True)
    BW_Spec_minus = models.CharField(max_length=255, blank=True, null=True)
    BW_Spec_plus = models.CharField(max_length=255, blank=True, null=True)
    Bandwidth = models.CharField(max_length=255, blank=True, null=True)
    Bandwidth_num = models.FloatField()
    Blocking = models.CharField(max_length=255, blank=True, null=True)
    Clear_Aperture = models.CharField(max_length=255, blank=True, null=True)
    Description = models.CharField(max_length=255, blank=True, null=True)
    Dimensions = models.CharField(max_length=255, blank=True, null=True)
    Dimensions_Spec_minus = models.CharField(max_length=255, blank=True, null=True)
    Dimensions_Spec_plus = models.CharField(max_length=255, blank=True, null=True)
    Flatness = models.CharField(max_length=255, blank=True, null=True)
    Item_category = models.CharField(max_length=255, blank=True, null=True)
    Item_classification = models.CharField(max_length=255, blank=True, null=True)
    MODID = models.CharField(max_length=255, blank=True, null=True)
    Minimum_Transmission = models.CharField(max_length=255, blank=True, null=True)
    Operating_Temperature = models.CharField(max_length=255, blank=True, null=True)
    Parallelism = models.CharField(max_length=255, blank=True, null=True)
    RECORDID = models.CharField(max_length=255, blank=True, null=True)
    Revision_Date = models.CharField(max_length=255, blank=True, null=True)
    Revision_Letter = models.CharField(max_length=255, blank=True, null=True)
    Ring_Depth = models.CharField(max_length=255, blank=True, null=True)
    Scratch_Dig = models.CharField(max_length=255, blank=True, null=True)
    Set_Components = models.TextField()
    Special_Specifications = models.CharField(max_length=255, blank=True, null=True)
    Special_Specs_A = models.CharField(max_length=255, blank=True, null=True)
    Special_Specs_B = models.CharField(max_length=255, blank=True, null=True)
    Special_Specs_C = models.CharField(max_length=255, blank=True, null=True)
    StdOrResale = models.CharField(max_length=255, blank=True, null=True)
    Thickness = models.CharField(max_length=255, blank=True, null=True)
    Thickness_Spec_minus = models.CharField(max_length=255, blank=True, null=True)
    Thickness_Spec_plus = models.CharField(max_length=255, blank=True, null=True)
    URL = models.CharField(max_length=1024, blank=True, null=True)
    WL_Spec_minus = models.CharField(max_length=255, blank=True, null=True)
    WL_Spec_plus = models.CharField(max_length=255, blank=True, null=True)
    Wavelength = models.CharField(max_length=255, blank=True, null=True)
    Wavelength_num = models.FloatField()    

    set_components = models.CharField(max_length=255, blank=True, null=True)

    # webqty fields
    quantity = models.IntegerField(default=0, blank=True, null=True)

    # Pricing/web_all fields
    curr_intl_base_price_a_stored = models.CharField(max_length=255, blank=True, null=True)
    curr_intl_base_price_b_stored = models.CharField(max_length=255, blank=True, null=True)
    curr_domestic_base_price_a_stored = models.CharField(max_length=255, blank=True, null=True)
    curr_domestic_base_price_b_stored = models.CharField(max_length=255, blank=True, null=True)
    Weight = models.FloatField(default='0.05')
    wavelength_range_high = models.CharField(max_length=255, blank=True, null=True)
    wavelength_range_low = models.CharField(max_length=255, blank=True, null=True)
    blocking_option_1 = models.CharField(max_length=255, blank=True, null=True)
    blocking_option_2 = models.CharField(max_length=255, blank=True, null=True)
    tx_option_1 = models.CharField(max_length=255, blank=True, null=True)
    tx_option_2 = models.CharField(max_length=255, blank=True, null=True)

    class Meta:
        pass

# class ProductIndex(indexes.SearchIndex, indexes.Indexable):
#     pass

class ProductAdmin(admin.ModelAdmin):
    list_display = ('part_number', 'category',)
    list_filter = ('category',)
    search_fields = ('part_number',)

admin.site.register(Product, ProductAdmin)