Question

这是 models.py ：

from django.db import models

class Location(models.Model):
   location_name = models.CharField(max_length=100)
   def __unicode__(self):
      return self.location_name

class Menu(models.Model):
   location = models.ManyToManyField(Location)
   restaurant_name = models.CharField(max_length=200)
   dish_category = models.CharField(max_length=100)
   dish_name = models.CharField(max_length=200)
   VNV_tag = models.CharField(max_length=100)
   quantity = models.CharField(max_length=10, default='FULL')
   price = models.CharField(max_length=5, default=0)
   def __unicode__(self):
       return self.restaurant_name

我正在尝试使用xlrd python模块从excel文件填充我的数据库。这是我的 populate_db.py 脚本：

import os
import xlrd
from menusearch.models import Menu, Location
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'midnitepro.settings')
import django
django.setup()

def populate():
    book = xlrd.open_workbook('/Users/Sahil/Desktop/MNFP1.xlsx')
    sheet = book.sheet_by_index(0)
    count1 = 0
    while count1<sheet.nrows:
        value_list = []
        count2 = 0
        while count2<sheet.ncols:
            value_list.append(sheet.row_values(count1, start_colx=count2, end_colx=count2+1))
            count2 +=1
        add_menuitem(value_list)
        count1 += 1

def add_menuitem(value_list):
    split_query = []
    m = Menu.objects.create()
    value_list = [str(x[0]).encode('utf-8') for x in value_list if x]

    m.restaurant_name = (value_list[0])
    m.dish_category = (value_list[1])
    m.dish_name = (value_list[2])
    m.VNV_tag = (value_list[3])
    m.quantity = (value_list[4])
    m.price = (value_list[5])
    # m.location.add(int(value_list[6]))

    split_query = (value_list[6]).split(",")
    for sq in split_query:
        l = Location.objects.get_or_create(location_name=sq)
        try:
            m.location.add(l)
        except ValueError:
            print "Problem Adding Location to Menu."

    m.save()

if __name__ == '__main__':
    print "Starting population script..."
    from menusearch.models import Menu, Location
    populate()

现在，当我运行populate_db.py脚本时，终端上的输出显示为：＆＃34; 问题将位置添加到菜单。＆＃34;。我在populate_db脚本中看到问题存在： m.location.add（l） 但是此查询集符合此处给出的语法：https://docs.djangoproject.com/en/1.8/topics/db/examples/many_to_many/

删除try / except后，我的回溯读取：

TypeError: int() argument must be a string or a number, not 'Location'

请解释这里发生的事情。以及如何通过查询集向 ManyToManyField 正确添加值。

可能重复：Django Error: TypeError: int() argument must be a string or a number, not 'BuildsTable' 但是我仍然想知道我的答案，因为我使用的是ManyToManyField。

完整追溯：

l= (<Location: Indiranagar>, False)

Inside Loop - sq=  Indiranagar
Traceback (most recent call last):
  File "populate_db.py", line 62, in <module>
populate()
  File "populate_db.py", line 23, in populate
add_menuitem(value_list)
  File "populate_db.py", line 50, in add_menuitem
m.location.add(l)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/fields/related.py", line 973, in add
self._add_items(self.source_field_name, self.target_field_name, *objs)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/fields/related.py", line 1079, in _add_items
'%s__in' % target_field_name: new_ids,
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/query.py", line 679, in filter
return self._filter_or_exclude(False, *args, **kwargs)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/query.py", line 697, in _filter_or_exclude
clone.query.add_q(Q(*args, **kwargs))
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1304, in add_q
clause, require_inner = self._add_q(where_part, self.used_aliases)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1332, in _add_q
allow_joins=allow_joins, split_subq=split_subq,
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1194, in build_filter
lookups, value)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/fields/related.py", line 1745, in get_lookup_constraint
root_constraint.add(lookup_class(targets[0].get_col(alias, sources[0]), value), AND)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/lookups.py", line 96, in __init__
self.rhs = self.get_prep_lookup()
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/lookups.py", line 134, in get_prep_lookup
return self.lhs.output_field.get_prep_lookup(self.lookup_name, self.rhs)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 729, in get_prep_lookup
return [self.get_prep_value(v) for v in value]
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 985, in get_prep_value
return int(value)
TypeError: int() argument must be a string or a number, not 'Location'.

Answer 1

要向ManyToManyField添加值，您需要通过将它们作为参数传递来添加它们。

add(obj1, obj2, obj3, ...)

这会将指定的对象添加到相关的对象集中。

您可以拨打add()，如下所示：

menu_object.location.add(loc_obj1, loc_obj2, ...)

在您的情况下，您需要执行以下操作：

l = Location.objects.get_or_create(location_name=sq)[0]

您需要通过索引instance访问0，因为get_or_create会返回元组(instance, created)。然后将此instance传递给add()方法。

注意：
使用具有多对多关系的add()不会为每个对象调用任何.save()，而是使用.bulk_create()创建关系。

Answer 2

我知道Rahul Gupta已经回答了这个问题。但是在更理论的层面上，我认为这就是你在这里使用get_or_create时发生的事情：

l = Location.objects.get_or_create(location_name=sq)

它返回一个元组，因此你必须通过修改它来调用它的第一个元素：

l = Location.objects.get_or_create(location_name=sq)[0]

只返回元组/字典的索引元素！

TypeError：int（）参数必须是字符串或数字，而不是＆＃39;模型实例＆＃39;

2 个答案: