python - 错误 : book. 书.作者 : (fields. E300) 书.书.作者 : (fields. E307)

Question

我的英语很差，抱歉

这是我的结构:

bookstore
---author(app1)
---book(app2)

或者在代码中:

from django.db import models
from author.models import Profile

from django.contrib import admin

class Book(models.Model):

      title        = models.CharField(max_length = 150)
      page         = models.IntegerField()
      price        = models.IntegerField()
      author = models.ForeignKey(
      'Profile',
      on_delete=models.CASCADE,)
  publish_date = models.DateField()

  class Meta(object):
    db_table = "book"

class BookAdmin(admin.ModelAdmin):
  pass

admin.site.register(Book, BookAdmin)

mysql 有一些数据，现在我想用它们来显示我的网页，而不是在数据库中创建数据。谢谢大家!

我有一个问题:

我的 Django == 1.9，python == 3，windows10

我想用mysql(我的数据库概念确实是这样做的)。当我找到一些资源时，我会看到python manage.py sql [appname] 它是 Django 到 SQL当我想使用Django到mysql时。我可以使用 python manage.pyspectdb 吗？它将有一个 models.pypython manage.py sql [应用程序名称] = python manage.pyspectdb?

错误:

book.Book.author: (fields.E300) Field defines a relation with model 'Profile', which is either not installed, or is abstract.
book.Book.author: (fields.E307) The field book.Book.author was declared with a lazy reference to 'book.profile', but app 'book' doesn't provide model 'profile'.

Answer 1

在您的 Book 中模型，您使用名为 author 的字段来引用到模型 Profile 。由于该模型是在另一个应用程序中定义的，因此您应该将其称为 app_name.ModelName ，很可能是:

class Book(models.Model):
    title = models.CharField(max_length = 150)
    page = models.IntegerField()
    price = models.IntegerField()
    author = models.ForeignKey(
        <b>'app1.Profile'</b>,  # add name of the app
        on_delete=models.CASCADE,
    )
    publish_date = models.DateField()

如果您将此模型命名为 Author但是，正如问题文本(而不是代码)似乎表明的那样，您应该使用 app1.Author 。当然你替换app1使用应用程序的真实名称。

ForeignKey [Django-doc] 中的文档对此进行了描述:

To refer to models defined in another application, you can explicitly specify a model with the full application label. For example, if the Manufacturer model above is defined in another application called production, you’d need to use:

class Car(models.Model):
    manufacturer = models.ForeignKey(
        'production.Manufacturer',
        on_delete=models.CASCADE,
    )