模型生成到数据库中是否有顺序？
在我的项目中，我需要更改上传文件的位置。这是使用 FileSystemStorage 完成的。文件上传的路径应该易于配置，例如使用 Django Admin。
from django.core.files.storage import FileSystemStorage
from django.db import models
class Setting(models.Model):
entry = models.CharField(primary_key=True, db_column="entry", max_length=50)
value = models.CharField(db_column="value", max_length=250, blank=True, null=True)
def __unicode__(self):
return "%s" %(self.entry)
class Meta:
db_table = 'settings'
verbose_name = 'Setting'
verbose_name_plural = 'Settings'
fs = FileSystemStorage(location=Setting.objects.get(entry__exact='upload_path').value)
def generate_filename(instance, filename):
...
class FileImport(models.Model):
data_file = models.FileField(_('Data file'), upload_to=generate_filename, storage=fs)
我收到此错误：
django.db.utils.DatabaseError： 关系“设置”不存在 从“settings”中选择“settings”.“entry”、“settings”.“value”。
第 1 行：...对于正在创建 FileSystemStorage 的行， 有没有办法告诉 Django 首先创建表设置（用于设置对象），然后用一些固定装置填充该表？
In my project I need to change the location where files are being uploaded. This is done using a FileSystemStorage. The path were the files are uploaded should be easy to configure, for example using the Django Admin.
from django.core.files.storage import FileSystemStorage
from django.db import models
class Setting(models.Model):
entry = models.CharField(primary_key=True, db_column="entry", max_length=50)
value = models.CharField(db_column="value", max_length=250, blank=True, null=True)
def __unicode__(self):
return "%s" %(self.entry)
class Meta:
db_table = 'settings'
verbose_name = 'Setting'
verbose_name_plural = 'Settings'
fs = FileSystemStorage(location=Setting.objects.get(entry__exact='upload_path').value)
def generate_filename(instance, filename):
...
class FileImport(models.Model):
data_file = models.FileField(_('Data file'), upload_to=generate_filename, storage=fs)
I receive this error:
django.db.utils.DatabaseError:
relation "settings" does not exist
LINE 1: ...ELECT "settings"."entry", "settings"."value" FROM "settings"...
for the line where FileSystemStorage is being created. Is there a way of telling Django to create table settings(for Setting objects) first and then fill this table with some fixtures?
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这并不能解决您的问题，因为
Settings表仍然不会被填充。将其移至类属性中，该属性在第一次实例化时进行初始化。That won't solve your problem, since the
Settingstable still won't be populated. Move it into a class attribute that gets initialized the first time it's instantiated.