穆蒂表继承和反向关系的Django

Question

我一直在阅读和实践的Django有关多表继承1.9文档和反向关系，这是我的代码：

@python_2_unicode_compatible 
class Place(models.Model): 
    name=models.CharField('Restaurant Name',max_length=50,db_column='name of restaurant') 
    address=models.CharField('Restaurant Address',max_length=50,db_column='address of restaurant') 

    def __str__(self): 
     return '%s and %s' % (self.name,self.address) 

@python_2_unicode_compatible 
class Restaurant(Place): 
    serves_hot_dogs=models.BooleanField(default=False) 
    serves_pizza=models.BooleanField(default=False) 
    owner=models.CharField(max_length=50) 
    parent_link=models.OneToOneField(Place,parent_link=True,default="",null=False) 

    def __str__(self): 
     return self.owner 

@python_2_unicode_compatible 
class Suplier(Place): 
    customers=models.ManyToManyField(Place,related_name='provider') 
    suplier_name=models.CharField(max_length=50) 

    def __str__(self): 
     return self.suplier_name 

@python_2_unicode_compatible 
class Consumer(Restaurant): 
    myrestaurant=models.ForeignKey(Restaurant,null=True,related_name='restaurant_consumer') 
    consumer_name=models.CharField(max_length=50,default=1) 

    def __str__(self): 
     return self.consumer_name 

为地方的关系ManyToManyField（父类）和Suplier（子类）按预期工作（提供“related_name”），但问题是，当我让另一个模型从另一个子（餐厅）继承，当我想使消费对象如下：

>>> from multitableinheritance.models import Place,Restaurant,Suplier,Consumer 
>>> Consumer.objects.all() 
[] 
>>> Consumer.objects.create(consumer_name='Andrew') 

它会引发“ValueError：invalid l int（）以10为底的iteral：''“。下面的完整错误。

Traceback (most recent call last): 
    File "<console>", line 1, in <module> 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/manager.py", line 122, in manager_method 
    return getattr(self.get_queryset(), name)(*args, **kwargs) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 401, in create 
    obj.save(force_insert=True, using=self.db) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 708, in save 
    force_update=force_update, update_fields=update_fields) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 735, in save_base 
    self._save_parents(cls, using, update_fields) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 759, in _save_parents 
    self._save_parents(cls=parent, using=using, update_fields=update_fields) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 760, in _save_parents 
    self._save_table(cls=parent, using=using, update_fields=update_fields) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 801, in _save_table 
    forced_update) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/base.py", line 831, in _do_update 
    filtered = base_qs.filter(pk=pk_val) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 790, in filter 
    return self._filter_or_exclude(False, *args, **kwargs) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/query.py", line 808, in _filter_or_exclude 
    clone.query.add_q(Q(*args, **kwargs)) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1243, in add_q 
    clause, _ = self._add_q(q_object, self.used_aliases) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1269, in _add_q 
    allow_joins=allow_joins, split_subq=split_subq, 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1203, in build_filter 
    condition = self.build_lookup(lookups, col, value) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/sql/query.py", line 1099, in build_lookup 
    return final_lookup(lhs, rhs) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/lookups.py", line 19, in __init__ 
    self.rhs = self.get_prep_lookup() 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/lookups.py", line 57, in get_prep_lookup 
    return self.lhs.output_field.get_prep_lookup(self.lookup_name, self.rhs) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.py", line 744, in get_prep_lookup 
    return self.get_prep_value(value) 
    File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.py", line 976, in get_prep_value 
    return int(value) 
ValueError: invalid literal for int() with base 10: '' 

我的问题是，是否有可能使模型关系继承从另一个子/ ChildClass，如果有可能是我的代码错误。顺便说一下，模型的迁移没有引起任何错误。谢谢你的回答和解释，对不起我的英文不好。

Answer 1

后，我尝试和修改我的代码，我终于可以让消费对象，这是我一直在修改代码（i到位类添加一个id属性，因为错误的自动字段类happends INI __init__.py线976）

@python_2_unicode_compatible 
class Place(models.Model): 
    name=models.CharField('Restaurant Name',max_length=50,db_column='name of restaurant') 
    address=models.CharField('Restaurant Address',max_length=50,db_column='address of restaurant') 
    #---> add Place Class attribute id <--- 
    id=models.PositiveIntegerField(default=1,primary_key=True,unique=True) 

    def __str__(self): 
     return '%s and %s' % (self.name,self.address) 

@python_2_unicode_compatible 
class Restaurant(Place): 
    serves_hot_dogs=models.BooleanField(default=False) 
    serves_pizza=models.BooleanField(default=False) 
    owner=models.CharField(max_length=50) 
    parent_link=models.OneToOneField(Place,parent_link=True,default="",null=False) 

    def __str__(self): 
     return self.owner 

@python_2_unicode_compatible 
class Suplier(Place): 
    customers=models.ManyToManyField(Place,related_name='provider') 
    suplier_name=models.CharField(max_length=50) 

    def __str__(self): 
     return self.suplier_name 

@python_2_unicode_compatible 
class Consumer(Restaurant): 
    myrestaurant=models.ForeignKey(Restaurant,null=True,related_name='restaurant_consumer',default=1) 
    consumer_name=models.CharField(max_length=50,default="") 

    def __str__(self): 
     return self.consumer_name 

也许有人可以进一步解释，id字段的多表继承