问题描述
在 Django Admin 中,我有一个名为 Modules 的模型。
当我尝试删除 Module 对象时,出现以下错误:
Deleting the module 'FR menu' would require deleting
the following protected related objects:
Module: FR menu
我理解为什么如果受保护对象是不同的模型会发生这种情况,但在这种情况下,警告指的是自身。
我什至不知道从哪里开始调试……也许是因为旧的迁移? . 此模型是称为 Prefix 的模型的外键模型,这是 模块模型声明:
positions = ('absolute','floating','none',)
corners = ('top left','top right','bottom left','bottom right',)
class Module(models.Model):
name = models.CharField(max_length=200,default='')
active = models.BooleanField(default=True,verbose_name='active',)
display_order = models.PositiveSmallIntegerField(default=0,verbose_name='display order')
sort1 = models.CharField(max_length=100,default='',verbose_name='main category',blank=True,)
sort2 = models.CharField(max_length=100,verbose_name='sub category',)
css_id = models.CharField(max_length=200,verbose_name='object ID',)
filename = models.CharField(max_length=200,verbose_name='SVG file (optional)',)
notes = RichTextField(default='')
cache_reset = models.BooleanField(default=False,verbose_name='delete cache (or visit example.com/c)',)
position = models.CharField(max_length=255,default='absolute',choices=Choices(*positions),verbose_name='placement')
corner = models.CharField(max_length=255,default='top left',choices=Choices(*corners),verbose_name='relative to')
horz_offset = models.FloatField(default=0,verbose_name='horizontal offset (px)',)
vert_offset = models.FloatField(default=0,verbose_name='vertical offset (px)',)
def __unicode__(self):
return self.name
def __str__(self):
return self.name
class Meta:
ordering = ['-active','display_order','name','sort1','sort2',]
verbose_name_plural = "2.2 · Modules"
class ModuleScripts(models.Model):
module = models.ForeignKey(Module,on_delete=models.CASCADE)
type = models.CharField(max_length=255,choices=Choices(*script_types),verbose_name='type')
name = models.CharField(max_length=200,default='')
content = models.TextField(max_length=50000,verbose_name='content',)
order = models.IntegerField(default=0,verbose_name='load order')
active = models.BooleanField(default=True,)
def __str__(self):
return self.name
class Meta:
verbose_name = "extra script"
verbose_name_plural = "extra scripts"
ordering = ["order"]
这里是 Prefix 模型声明,其中包括作为外键的模块:
class Prefix(models.Model):
display_order = models.PositiveSmallIntegerField(default=0,verbose_name='display order')
path = models.CharField(max_length=2,verbose_name='code',)
default = models.CharField(max_length=20,verbose_name='default page')
responsive = models.ForeignKey(Responsive,default=0,on_delete=models.PROTECT,verbose_name='screen',)
language = models.ForeignKey(Language,)
module = models.ManyToManyField(Module,through='PrefixModules')
def __str__(self):
return self.path
class Meta:
verbose_name = "Combination Code"
verbose_name_plural = "1.4 · Combination Codes"
ordering = ['display_order']
class PrefixModules(models.Model):
module = models.ForeignKey(Module,on_delete=models.PROTECT)
prefix = models.ForeignKey(Prefix,on_delete=models.PROTECT)
zindex = models.IntegerField(default=0,verbose_name='z index')
active = models.BooleanField(default=True,)
def __str__(self):
return self.module.name
class Meta:
verbose_name = "module"
verbose_name_plural = "modules"
ordering = ["zindex"]
解决方法
Module
似乎基于其 PrefixModules
来指代 verbose_name
,因此该错误很可能是指要求在 PrefixModules
之前先删除 Module
,因为外键被声明为 module = models.ForeignKey(Module,on_delete=models.PROTECT)
这个问题教会了我正确命名模型的重要性。
问题出现是因为我使用了与 ForeignKey 和根模型相同的模型名称。
因此,“需要删除以下受保护的相关对象”消息似乎指的是它自己,而实际上它的意思是:
Deleting the ROOT MODEL module 'FR menu' would require deleting
the following protected related objects:
Module FOREIGNKEY USED BY PREFIX: FR menu
长期的解决方案是避免模棱两可的模型名称和同名的多次使用。