django自定义模板标签-导入模型博客错误

Question

I am trying to import a model class called BlogDetails to use in my customised template tags page.

Here is the structure of my app:

appname (directory)
  -->core (directory)
    -->models.py (file)
    -->templatetags (directory)
      -->customised_template_tags.py (file)

Here is the import statements in the customised_template_tags.py file. This is the same structure of other import statements I have used in my view files:

import datetime
import os

from django import template
from django.conf import settings
from django.templatetags.static import static
from django.utils.safestring import mark_safe
from django.utils.translation.trans_real import gettext

from appname.common.utils import get_supported_language_code
from appname.core.models import BlogDetails

register = template.Library()

Here is the import statement on the models.py file at line 76 (refered to in the error message) that imports code from the customised_template_tags.py file:

from appname.core.templatetags.customised_template_tags import absolute_static, alternative_file, \
    file_url

Here is the error message:

  File "C:\Users\me\desktop\appname\appname\core\models.py", line 76, in <module>
    from appname.core.templatetags.customised_template_tags import absolute_static, alternative_file, \
  File "C:\Users\me\desktop\appname\appname\core\templatetags\customised_template_tags.py", line 11, in <module>
    from appname.core.models import BlogDetails
ImportError: cannot import name 'BlogDetails'

I have re-started my development server and I have read this thread and followed the suggestions in the answer and I have also read the django docs .

Can anyone suggest the solution to my issue?

Answer 1

You do a circular import:

1. appname.core.models tries to import appname.core.templatetags.customised_template_tags
2. appname.core.templatetags.customised_template_tags tries to import appname.core.models
3. Because appname.core.models hasn't finished to load, it can't be imported, so it fails.

A quick fix:

Import your model inside your tag function.
Or the opposite, import your tag only in the function where you use it.