Django模型实例full_clean方法，对吗？

Question

我想要做的是编写代码，它允许我从csv文件批量加载Django对象实例。很明显，我应该在保存任何内容之前先检查所有数据。

tl; dr：full_clean（）方法无法捕获即将尝试在没有null=True的字段中保存无。似乎不正当。这是由设计，如果是这样，为什么？ Django的bug比我曾经使用过的其他任何东西都少，所以“Bug！”似乎最不可能。

完整版。我认为会工作的是每行，创建一个对象实例，用电子表格中的数据填充字段，然后调用full_clean方法。即（轮廓）

from django.core.exceptions import ValidationError 
... 

# upload a CSV file and open with a csvreader 
errors=[] 
for rownumber, row in enumerate(csvreader): 

    o = SomeDjangoModel() 
    o.somefield = row[0] # repeated for all input data row[1] ... 

    try: 
     reason = "" 
     o.full_clean() 
    except ValidationError as e: 
     reason = "Row:{} Reason:{}".format(rownumber, str(e)) 
     errors.append(reason) 
     # reason, together with the row-number of the csv file, fully explains 
     # what is wrong. 

# end of loop 
if errors: 
    # display errors to the user for him to fix 
else: 
    # repeat the loop, doing .save() instead of .full_clean() 
    # and get database integrity errors trying to save Null in non-null model field. 

麻烦的是，.full_clean()不赶领域没有值，而不null=True

我应该怎么做？想法包括

1. 包住整个事情在一个事务中，做了一批o.save（）异常处理程序内的，并滚动整个事务回，除非没有任何错误。但是，为什么在90％的尝试会以不重要的方式出错时会打扰数据库呢？

2. 通过表单提交数据，即使与用户没有表单级的每行交互。

3. 手动测试无应该在哪里。但是还有什么.full_clean没有检查？

我可以理解，最终赶上数据库完整性错误的唯一方法就是尝试存储数据，但为什么不Django的在空独自捕获无=假场？

BTW这是Django的1.9.6

添加的细节。这是模型定义

class OrderHistory(models.Model): 
    invoice_no = models.CharField(max_length=10, unique=True)   # no default 
    invoice_val= models.DecimalField(max_digits=8, decimal_places=2) # no default 
    date  = models.DateField()         # no default 

的相关领域，这是发生了什么，从python manage.py shell完成，以证明.full_clean方法无法发现的

>>> from orderhistory.models import OrderHistory 
>>> from datetime import date 
>>> o = OrderHistory(date=date(2010,3,17), invoice_no="21003163") 
>>> o.invoice_val=None 
>>> o.full_clean() # passes clean 
>>> o.save() # attempt to save this one which has passed full_clean() validation 
Traceback (most recent call last): 
    File "<console>", line 1, in <module> 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/models/base.py", line 708, in save 
force_update=force_update, update_fields=update_fields) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/models/base.py", line 736, in save_base 
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/models/base.py", line 820, in _save_table 
result = self._do_insert(cls._base_manager, using, fields, update_pk, raw) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/models/base.py", line 859, in _do_insert 
using=using, raw=raw) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/models/manager.py", line 122, in manager_method 
return getattr(self.get_queryset(), name)(*args, **kwargs) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/models/query.py", line 1039, in _insert 
return query.get_compiler(using=using).execute_sql(return_id) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 1060, in execute_sql 
cursor.execute(sql, params) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/backends/utils.py", line 79, in execute 
return super(CursorDebugWrapper, self).execute(sql, params) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute 
return self.cursor.execute(sql, params) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/utils.py", line 95, in __exit__ 
six.reraise(dj_exc_type, dj_exc_value, traceback) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/utils/six.py", line 685, in reraise 
raise value.with_traceback(tb) 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/backends/utils.py", line 64, in execute 
    return self.cursor.execute(sql, params) 
django.db.utils.IntegrityError: null value in column "invoice_val" violates not-null constraint 
DETAIL: Failing row contains (2, 21003163, , , 2010-03-17, , null, null, null, null, null, null). 
>>> 
>>> p = OrderHistory(invoice_no="21003164") # no date 
>>> p.date=None 
>>> p.full_clean()       # this DOES error as it should 
    Traceback (most recent call last): 
    File "<console>", line 1, in <module> 
    File "/home/nigel/.virtualenvs/edge22/lib/python3.4/site-packages/django/db/models/base.py", line 1144, in full_clean 
    raise ValidationError(errors) 
django.core.exceptions.ValidationError: {'date': ['This field cannot be null.']} 
>>> 

Answer 1

我刚才重复你的步骤在外壳和full_clean（）触发ValidationError为无值：

>>> from orders.models import OrderHistory 
>>> o = OrderHistory() 
>>> o.full_clean() 
Traceback (most recent call last): 
    File "<console>", line 1, in <module> 
    File "/Users/oz/.virtualenvs/full_clean_test/lib/python2.7/site-packages/django/db/models/base.py", line 1144, in full_clean 
    raise ValidationError(errors) 
ValidationError: {'date': [u'This field cannot be null.'], 'invoice_val': [u'This field cannot be null.'], 'invoice_no': [u'This field cannot be blank.']} 

我在OSX和Pyth使用Django 1.9.6和Python 2.7.10测试了新项目在Ubuntu的3.4.3上。

尝试从您的项目中删除所有* .pyc文件。如果这不起作用，请删除虚拟环境，创建新环境并重新安装依赖项。