使用多个数据库（Postgresql 8.4和sqlite3）时出现Django“无法适应类型”错误

Question

简要说明
使用本地（sqlite3）数据库，我可以保存和提取信息，但是当使用我的生产服务器（另一台机器上的postgresql8.4）时，Django会抛出一个“cannotadapttype”错误。有人能帮我指出一个好的方向开始调试这个吗？在

背景
python项目使用django1.3实现对多个数据库（生产和调试）的ORM。多数据库连接在所有情况下都有效，但这次除外。在搜索SO和Google时，大多数错误都是通过重新运行syncdb来修复的。我在我的生产服务器和调试服务器上都这样做了，但仍然得到相同的错误。在看了模型、访问器和变异器之后，我看不出这个函数有什么不同。我已经包括了可疑函数、我的模型和错误消息。任何帮助都将不胜感激。我很乐意发布任何其他非敏感信息。在

系统信息
*Postgresql 8.4-Ubuntu服务器
*Django项目（客户端/用户）-Windows XP（如图所示）、Mac OSX、Windows 7（64位）
*Python 2.7.1
*心理2
*Django 1.3款

模型.py

from django.db import models

# Create your models here.
class Card_Test(models.Model):
    name = models.TextField(max_length=100)
    description = models.TextField(max_length=200)
    units = models.TextField(max_length=500)
    result_tags = models.TextField(max_length=500)

    def __unicode__(self):
        return self.name

class Status_Type(models.Model):
    status = models.CharField(max_length=25)

    def __unicode__(self):
        return self.status

class Card_Test_List(models.Model):
    card_id = models.ForeignKey('Card')
    card_test_id = models.ForeignKey('Card_Test')
    card_test_sub_id = models.PositiveIntegerField()
    status       = models.ForeignKey('Status_Type')
    result       = models.TextField()
    ran_on       = models.DateField()
    ran_by       = models.CharField(max_length=50)
    run_number   = models.PositiveIntegerField()

    def __unicode__(self):
        return self.card_test_id.__unicode__()

class Card_Type(models.Model):
    card_type = models.CharField(max_length=25)

    def __unicode__(self):
        return self.card_type

class Card(models.Model):
    serial_number = models.CharField(max_length=25)
    card_type = models.ForeignKey('Card_Type')
    status = models.ForeignKey('Status_Type')
    card_tests = models.ManyToManyField('Card_Test', through='Card_Test_List')

    def __unicode__(self):
        return self.serial_number

    def print_all_cards(self):
        print Card.objects.all()

class System_Test_Type(models.Model):
    test_type = models.CharField(max_length=25)

    def __unicode__(self):
        return self.test_type

class System_Test(models.Model):
    name        = models.CharField(max_length=100)
    description = models.CharField(max_length=100)
    units       = models.CharField(max_length=100)

    def __unicode__(self):
        return self.name


class System_Test_List(models.Model):
    chassis_id = models.ForeignKey('Chassis')
    system_test_id = models.ForeignKey('System_Test') 
    result     = models.CharField(max_length=25)
    ran_on     = models.DateField()
    ran_by     = models.CharField(max_length=50)
    test_type  = models.ForeignKey('System_Test_Type')

    def __unicode__(self):
        return self.system_test_id.__unicode__()

class Chassis(models.Model):
    serial_number = models.CharField(max_length=25)
    slot_311 = models.ForeignKey(Card, related_name='slot1_card')
    slot_175 = models.ForeignKey(Card, related_name='slot2_card')
    slot_345 = models.ForeignKey(Card, related_name='slot3_card')
    slot_346 = models.ForeignKey(Card, related_name='slot4_card')
    slot_344 = models.ForeignKey(Card, related_name='slot5_card')
    slot_178 = models.ForeignKey(Card, related_name='slot6_card')
    backplane_serial = models.TextField(max_length=25)
    site_location    = models.TextField(max_length=25)
    status_env_70c  = models.ForeignKey('Status_Type', related_name='70C')
    status_env_10c  = models.ForeignKey('Status_Type', related_name='10C')
    status_assembly = models.ForeignKey('Status_Type', related_name='assembly')
    status_final    = models.ForeignKey('Status_Type', related_name='final')
    system_test = models.ManyToManyField(System_Test, through='System_Test_List')

    def __unicode__(self):
        return self.serial_number

设置.py摘录

^{pr2}$

接受器/变异器

同时适用于调试和生产数据库

def get_chassis_by_sn(chassis_id):
    try:
        return Chassis.objects.using(get_database()).filter(serial_number__iexact=chassis_id)
    except Chassis.DoesNotExist:
        return []

仅对调试数据库有效。如果行上的注释失败，请参见

def modify_chassis_sn(current, new):
    #chassis = Chassis.objects.using(get_database()).filter(serial_number__iexact=current)
    try:
        chassis = Chassis.objects.using(get_database()).filter(serial_number__iexact=current)
    except Chassis.DoesNotExist:
        err.Handle_MUX_Error('Unknown Chassis / Serial Number')
        return False
    chassis = chassis[0] # <--- Fails here

    # Update the serial number
    chassis.serial_number = new
    chassis.save(using=get_database())
    return True

def modify_chassis_record(sn, slots=None, bp_sn=None, site_loc=None ):

    #chassis = Chassis.objects.using(get_database()).filter(serial_number__iexact=sn)

    try:
        c = Chassis.objects.using(get_database()).filter(serial_number__iexact=sn)
        print len(c)
    except Chassis.DoesNotExist:
        err.Handle_MUX_Error('Unknown Chassis / Serial Number')
        return False
    chassis = c[0]  # <--- Fails here

    # Update the List of Cards (if provided)
    if slots != None:
        if len(slots) != 6:
            err.Handle_MUX_Error('You must enter 6 serial numbers!')
            return False

        index = 0
        db_slots = [None]*6
        for slot in slots:
            s = get_card_by_sn(slot)

            if len(s) == 0:
                err.Handle_MUX_Error('Slot ' + str(index) + ' serial number does not exist!')
                return False

            db_slots[index] = s[0]
            index +=1

        chassis.slot_311 = db_slots[0]
        chassis.slot_175 = db_slots[1]
        chassis.slot_345 = db_slots[2]
        chassis.slot_346 = db_slots[3]
        chassis.slot_344 = db_slots[4]
        chassis.slot_178 = db_slots[5]

    # Update the Backplane Serial Number (if provided)
    if bp_sn != None:
        chassis.backplane_serial = bp_sn

    # Update the site Location (if provided)
    if site_loc != None:
        chassis.site_location = site_loc

    # Save all changes to the chassis
    print chassis
    chassis.save(using=get_database())
    return True

错误消息

Traceback (most recent call last):
  File "C:\Documents and Settings\User\Desktop\Python\exe\wx_gui\Assembly_Panel.py", line 276, in SaveChassis
    mux_api.modify_chassis.run(active_chassis, new_chassis_id, bp_sn=backplane_sn)
  File "C:\Documents and Settings\User\Desktop\Python\exe\api_rehabilitation_suite\modify_chassis.py", line 10, in run
    modify_status = db.modify_chassis_record(sn, slots=slots, bp_sn=bp_sn, site_loc=site_loc )
  File "C:\Documents and Settings\User\Desktop\Python\mux_test_data\db_driver.py", line 136, in modify_chassis_record
    print len(c)
  File "C:\Python27\lib\site-packages\django\db\models\query.py", line 82, in __len__
    self._result_cache = list(self.iterator())
  File "C:\Python27\lib\site-packages\django\db\models\query.py", line 273, in iterator
    for row in compiler.results_iter():
  File "C:\Python27\lib\site-packages\django\db\models\sql\compiler.py", line 680, in results_iter
    for rows in self.execute_sql(MULTI):
  File "C:\Python27\lib\site-packages\django\db\models\sql\compiler.py", line 735, in execute_sql
    cursor.execute(sql, params)
  File "C:\Python27\lib\site-packages\django\db\backends\util.py", line 34, in execute
    return self.cursor.execute(sql, params)
  File "C:\Python27\lib\site-packages\django\db\backends\postgresql_psycopg2\base.py", line 44, in execute
    return self.cursor.execute(query, args)
django.db.utils.DatabaseError: can't adapt type 'Chassis'

Answer 1

结果表明，当在Django过滤器中使用值时，sqlite3忽略并尝试将其转换为字符串。在GUI中，我传递的是实际的机箱对象，而不是序列号。Postgresql在尝试将机箱对象用作序列号时抛出错误，而sqlite3忽略它并将其转换为字符串（我在Django中将其定义为序列号）。在

我希望这个发现可以帮助其他人调试这种类型的错误。在

感谢所有调查此事的人。在