Django報錯之...doesn't declare an explicit app_label...

Django 啟動項目服務的時候可能會報以下錯誤：以下Apps.userPage是應用名，換成你自己的！！！

單項目不太可能會遇到這個問題，一般多應用放在一個Apps下時可能會出現.doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS

  File "D:\Fineex WorkSpace\DatasPlat\Apps\userPage\urls.py", line 18, in <module>
    from . import views
  File "D:\Fineex WorkSpace\DatasPlat\Apps\userPage\views.py", line 6, in <module>
    from . import models
  File "D:\Fineex WorkSpace\DatasPlat\Apps\userPage\models.py", line 6, in <module>
    class Department(models.Model):
  File "D:\Fineex WorkSpace\DatasPlat\venv\lib\site-packages\django\db\models\base.py", line 113, in __new__
    raise RuntimeError(
RuntimeError: Model class Apps.userPage.models.Department doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS.

如果你確信在models.py中正確添加了對應的Model：

class Department(models.Model):
    code = models.CharField(max_length=64, blank=False, null=False, primary_key=True, unique=True)
    name = models.CharField(max_length=128, blank=False, null=False)
    pcode = models.CharField(max_length=64)
    desc = models.CharField(max_length=255, blank=True, null=True)
    lever= models.IntegerField(blank=False, null=False)
    class Meta:
        db_table = 'department'
        verbose_name_plural = db_table

如果你確信在settings.py中已正確注冊App

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'Apps.userPage',
    .......

且在Apps/userPage/view.py中按照正確路徑（一般為相對路徑）

from . import models

如果你覺得不應該報錯，甚至你Apps下面的其它App沒有這個錯誤，或者刪除上面的引入都可以正常啟動項目的話，錯誤大概率出險在Apps/userPage/apps.py的AppConfig類中，

class UserpageConfig(AppConfig):
    default_auto_field = 'django.db.models.BigAutoField'
    name = 'userPage' # 出錯點在這里

改成

class UserpageConfig(AppConfig):
    default_auto_field = 'django.db.models.BigAutoField'
    name = 'Apps.userPage' 

或者直接在apps.py中刪掉這個Config，再次啟動這個項目，已成功！

只是Django項目啟動報錯的一種情況，不一定適用於其它類型，先判斷好。