django：从 postgres 数据库导入数据时出现无法适应错误

Question

我在从转储数据安装固定装置时遇到奇怪的错误。我正在使用 psycopg2 和 django1.1.1

silver:probsbox oleg$ python manage.py loaddata /Users/oleg/probs.json 
Installing json fixture '/Users/oleg/probs' from '/Users/oleg/probs'.
Problem installing fixture '/Users/oleg/probs.json': Traceback (most recent call last):
  File "/opt/local/lib/python2.5/site-packages/django/core/management/commands/loaddata.py", line 153, in handle
    obj.save()
  File "/opt/local/lib/python2.5/site-packages/django/core/serializers/base.py", line 163, in save
    models.Model.save_base(self.object, raw=True)
  File "/opt/local/lib/python2.5/site-packages/django/db/models/base.py", line 495, in save_base
    result = manager._insert(values, return_id=update_pk)
  File "/opt/local/lib/python2.5/site-packages/django/db/models/manager.py", line 177, in _insert
    return insert_query(self.model, values, **kwargs)
  File "/opt/local/lib/python2.5/site-packages/django/db/models/query.py", line 1087, in insert_query
    return query.execute_sql(return_id)
  File "/opt/local/lib/python2.5/site-packages/django/db/models/sql/subqueries.py", line 320, in execute_sql
    cursor = super(InsertQuery, self).execute_sql(None)
  File "/opt/local/lib/python2.5/site-packages/django/db/models/sql/query.py", line 2369, in execute_sql
    cursor.execute(sql, params)
  File "/opt/local/lib/python2.5/site-packages/django/db/backends/util.py", line 19, in execute
    return self.cursor.execute(sql, params)
ProgrammingError: can't adapt

首先我在互联网上检查了类似的问题。这似乎非常相关： http://code.djangoproject.com/ticket/5996，因为我的数据有许多非 ASCII 符号

但实际上我已经检查了我的 django 安装，那里没问题

你能建议什么是错误的

====

按照第一个答案的建议添加打印语句后继续调查。日志看起来是这样的：

silver:probsbox oleg$ python manage.py loaddata /Users/oleg/probs.json 
Installing json fixture '/Users/oleg/probs' from '/Users/oleg/probs'.
<DeserializedObject: Novice>
<DeserializedObject: Junior>
<DeserializedObject: Chess enthusiast>
<DeserializedObject: Experienced player >
<DeserializedObject: Smart player>
Problem installing fixture '/Users/oleg/probs.json': Traceback (most recent call last):
  File "/opt/local/lib/python2.5/site-packages/django/core/management/commands/loaddata.py", line 153, in handle
    print obj
  File "/opt/local/lib/python2.5/site-packages/django/core/serializers/base.py", line 155, in __repr__
    return "<DeserializedObject: %s>" % smart_str(self.object)
  File "/opt/local/lib/python2.5/site-packages/django/utils/encoding.py", line 107, in smart_str
    return str(s)
  File "/opt/local/lib/python2.5/site-packages/django/db/models/base.py", line 335, in __str__
    return force_unicode(self).encode('utf-8')
  File "/opt/local/lib/python2.5/site-packages/django/utils/encoding.py", line 71, in force_unicode
    s = unicode(s)
  File "/Users/oleg/Sites/probsbox/registration/models.py", line 58, in __unicode__
    return u"%s's profile" %(self.user.username)
  File "/opt/local/lib/python2.5/site-packages/django/db/models/fields/related.py", line 257, in __get__
    rel_obj = QuerySet(self.field.rel.to).get(**params)
  File "/opt/local/lib/python2.5/site-packages/django/db/models/query.py", line 305, in get
    % self.model._meta.object_name)
DoesNotExist: User matching query does not exist.

silver:probsbox oleg$ 

来自最后一条评论的错误

<DeserializedObject: qwert2000's profile>

安装固定装置'/Users/oleg/probs.json'时出现问题：回溯（最近一次调用最后）： 文件“/opt/local/lib/python2.5/site-packages/django/core/management/commands/loaddata.py”，第 154 行，在句柄中 obj.save() 文件“/opt/local/lib/python2.5/site-packages/django/core/serializers/base.py”，第 163 行，保存 models.Model.save_base(self.object, raw=True) 文件“/opt/local/lib/python2.5/site-packages/django/db/models/base.py”，第 495 行，在 save_base 中 结果 = manager._insert(值, return_id=update_pk) 文件“/opt/local/lib/python2.5/site-packages/django/db/models/manager.py”，第 177 行，在 _insert 中 返回 insert_query(self.model, 值, **kwargs) 文件“/opt/local/lib/python2.5/site-packages/django/db/models/query.py”，第 1087 行，在 insert_query 中 返回查询.execute_sql(return_id) 文件“/opt/local/lib/python2.5/site-packages/django/db/models/sql/subqueries.py”，第320行，在execute_sql中 游标 = super(InsertQuery, self).execute_sql(无) 文件“/opt/local/lib/python2.5/site-packages/django/db/models/sql/query.py”，第2369行，在execute_sql中 光标.执行（sql，参数） 文件“/opt/local/lib/python2.5/site-packages/django/db/backends/util.py”，第 19 行，执行中 返回 self.cursor.execute(sql, params) 编程错误：无法适应

Answer 1

当 psycopg2 收到不知道如何转换为 SQL 语句的值的数据类型时，会引发无法适应错误。例如，如果您不小心传递了一个列表，例如，对于一个应该是整数的值，psycopg2 将引发此无法适应错误。

psycopg2 源代码发行版附带的 faq.txt 文档是这样解释的：

为什么!cursor.execute()会引发异常无法适应？

Psycopg 通过查找将 Python 对象转换为 SQL 字符串表示形式
在对象类中。当您尝试通过时会引发异常
作为查询参数，没有为其注册适配器的对象
它的阶级。有关信息，请参阅：ref:adapting-new-types。

查找有问题的值的最佳第一步可能是在完全详细模式下运行 loaddata： python manage.py loaddata --verbosity=2 /Users/oleg/probs.json

好吧，我希望loaddata 的详细信息是可行的，而且我不必承认我从未找到一种使用 django 的 loaddata 调试适应错误的优雅方法。过去，我曾在 django 的 loaddata 函数中插入打印语句，以便在发生错误时可以看到正在反序列化的值。我已经编辑了django/core/management/loaddata.py。查看 handle() 函数中的 obj.save()。我希望这个坦白能够激励有人分享更好的解决方案:-)

Answer 2

好吧，我结束了从数据库复制转储，并在没有 python 的情况下在本地恢复它......