我写的代码（只贴主要部分）：admin.pyfromdjango.contribimportadminfrom.modelsimportTag,Category,ArticleclassArticleAdmin(admin.ModelAdmin):defsave_model(self,request,obj,form,change):obj.author=request.userobj.save()admin.site.register(Tag)admin.site.register(Category)admin.site.register(Article)models.pyfromdjango.dbimportmodelsfromdjango.contrib.auth.modelsimportUserclassTag(models.Model):classMeta:verbose_name='标签'verbose_name_plural=verbose_nametag_name=models.CharField('标签名',max_length=20)create_time=models.DateTimeField('创建时间',auto_now_add=True)def__str__(self):returnself.tag_nameclassCategory(models.Model):classMeta:verbose_name='分类'verbose_name_plural=verbose_namename=models.CharField('分类名',max_length=20)def__str__(self):returnself.nameclassArticle(models.Model):classMeta:verbose_name='文章'verbose_name_plural=verbose_nameordering=['-updated_time','-created_time']title=models.CharField('标题',max_length=60)content=models.TextField('正文')category=models.ManyToManyField(Category,verbose_name='分类',blank=True)author=models.ForeignKey(User,verbose_name='作者',editable=False)tags=models.ForeignKey(Tag,verbose_name="标签",related_name='tags_article',blank=True)view_count=models.IntegerField('浏览次数',editable=False,default=0)created_time=models.DateTimeField('添加时间',auto_now_add=True)updated_time=models.DateTimeField('修改时间',auto_now=True)def__str__(self):returnself.title在后台增加文章，抛出错误：InternalServerError:/admin/blog/article/add/Traceback(mostrecentcalllast):File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\backends\utils.py",line65,inexecutereturnself.cursor.execute(sql,params)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\backends\sqlite3\base.py",line328,inexecutereturnDatabase.Cursor.execute(self,query,params)sqlite3.IntegrityError:NOTNULLconstraintfailed:blog_article.author_idTheaboveexceptionwasthedirectcauseofthefollowingexception:Traceback(mostrecentcalllast):File"C:\Users\cxgre\fancyblog\lib\site-packages\django\core\handlers\exception.py",line41,ininnerresponse=get_response(request)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\core\handlers\base.py",line187,in_get_responseresponse=self.process_exception_by_middleware(e,request)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\core\handlers\base.py",line185,in_get_responseresponse=wrapped_callback(request,*callback_args,**callback_kwargs)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\contrib\admin\options.py",line551,inwrapperreturnself.admin_site.admin_view(view)(*args,**kwargs)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\utils\decorators.py",line149,in_wrapped_viewresponse=view_func(request,*args,**kwargs)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\views\decorators\cache.py",line57,in_wrapped_view_funcresponse=view_func(request,*args,**kwargs)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\contrib\admin\sites.py",line224,ininnerreturnview(request,*args,**kwargs)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\contrib\admin\options.py",line1508,inadd_viewreturnself.changeform_view(request,None,form_url,extra_context)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\utils\decorators.py",line67,in_wrapperreturnbound_func(*args,**kwargs)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\utils\decorators.py",line149,in_wrapped_viewresponse=view_func(request,*args,**kwargs)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\utils\decorators.py",line63,inbound_funcreturnfunc.__get__(self,type(self))(*args2,**kwargs2)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\contrib\admin\options.py",line1408,inchangeform_viewreturnself._changeform_view(request,object_id,form_url,extra_context)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\contrib\admin\options.py",line1448,in_changeform_viewself.save_model(request,new_object,form,notadd)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\contrib\admin\options.py",line979,insave_modelobj.save()File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\models\base.py",line806,insaveforce_update=force_update,update_fields=update_fields)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\models\base.py",line836,insave_baseupdated=self._save_table(raw,cls,force_insert,force_update,using,update_fields)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\models\base.py",line922,in_save_tableresult=self._do_insert(cls._base_manager,using,fields,update_pk,raw)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\models\base.py",line961,in_do_insertusing=using,raw=raw)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\models\manager.py",line85,inmanager_methodreturngetattr(self.get_queryset(),name)(*args,**kwargs)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\models\query.py",line1063,in_insertreturnquery.get_compiler(using=using).execute_sql(return_id)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\models\sql\compiler.py",line1099,inexecute_sqlcursor.execute(sql,params)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\backends\utils.py",line80,inexecutereturnsuper(CursorDebugWrapper,self).execute(sql,params)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\backends\utils.py",line65,inexecutereturnself.cursor.execute(sql,params)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\utils.py",line94,in__exit__six.reraise(dj_exc_type,dj_exc_value,traceback)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\utils\six.py",line685,inreraiseraisevalue.with_traceback(tb)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\backends\utils.py",line65,inexecutereturnself.cursor.execute(sql,params)File"C:\Users\cxgre\fancyblog\lib\site-packages\django\db\backends\sqlite3\base.py",line328,inexecutereturnDatabase.Cursor.execute(self,query,params)django.db.utils.IntegrityError:NOTNULLconstraintfailed:blog_article.author_id我该怎么做呢？