Djangopyodbcazure SQL Server参数限制

Question

詹戈：1.11

我使用django-pyodbc-azure作为我的Django后端。它正在连接到SQL Server 2012。SQL Server的参数限制为2100个。当我试图在将返回2100多个结果的查询集上使用prefetch_related时。。。在

def object_search_list(request):
    objects = MyModel.objects.filter(some_field='filter value').select_related('another_field').prefetch_related('a_third_field')
    print(objects)
    return render(request, 'objects/object_list.html', {'objects':objects})

…返回此错误：

^{pr2}$

它指向django-pyodbc-azure使用的pyodbc后端。当查看特征（https://github.com/michiya/django-pyodbc-azure/blob/azure-2.1/sql_server/pyodbc/features.py）时，没有max_query_params集。我试图手动添加max_query_params = 2100。这导致了同样的错误。将该值设置为2000和1000也会导致相同的错误。在

如何调整django-pyodbc-azure以自动处理此SQL Server限制？在

用于Django的Oracle后端具有如下特性：https://github.com/django/django/blob/master/django/db/backends/oracle/features.py

更新：

我意识到max_query_params这个名称对于Django 2.0来说是新的。因此，我尝试了max_limit_in_size来匹配django1.11。只是因为django-pyodbc-azure不支持控制参数计数，base.py覆盖了Django的默认base.py？在

更新2:

我升级到Django 2.1并升级了django-pyodbc-azure以匹配。然后我编辑了features.py，将max_query_params = 2000添加为一个特性。在Django本地后端中出现max_query_params的另一个位置是此函数中的operations.py（Oracle示例）：

def bulk_batch_size(self, fields, objs):
    """Oracle restricts the number of parameters in a query."""
    if fields:
        return self.connection.features.max_query_params // len(fields)
    return len(objs)

django-pyodbc-azure也有这个功能，看起来像这样：

def bulk_batch_size(self, fields, objs):
    """
    Returns the maximum allowed batch size for the backend. The fields
    are the fields going to be inserted in the batch, the objs contains
    all the objects to be inserted.
    """
    objs_len, fields_len, max_row_values = len(objs), len(fields), 1000
    if (objs_len * fields_len) <= max_row_values:
        size = objs_len
    else:
        size = max_row_values // fields_len
    return size

它似乎已经处理了将max_row_values设置为1000的批处理。然而，同样的错误仍然存在。我也试着把1000改成max_query_params，但没有用。在

以下是完整的回溯：

Traceback:

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in _execute
  85.                 return self.cursor.execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\sql_server\pyodbc\base.py" in execute
  546.             return self.cursor.execute(sql, params)

The above exception (('07002', '[07002] [Microsoft][SQL Server Native Client 11.0]COUNT field incorrect or syntax error (0) (SQLExecDirectW)')) was the direct cause of the following exception:

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\core\handlers\exception.py" in inner
  34.             response = get_response(request)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\core\handlers\base.py" in _get_response
  126.                 response = self.process_exception_by_middleware(e, request)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\core\handlers\base.py" in _get_response
  124.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\contrib\auth\decorators.py" in _wrapped_view
  21.                 return view_func(request, *args, **kwargs)

File "C:\Users\user\djangoproject\app\views.py" in object_list
  486.     return render(request, 'objects/object_list.html', {'objects':objects})

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\shortcuts.py" in render
  36.     content = loader.render_to_string(template_name, context, request, using=using)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\loader.py" in render_to_string
  62.     return template.render(context, request)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\backends\django.py" in render
  61.             return self.template.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\template_timings_panel\panels\TemplateTimings.py" in timing_hook
  139.         result = func(self, *args, **kwargs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  171.                     return self._render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\test\utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  937.                 bit = node.render_annotated(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render_annotated
  904.             return self.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\loader_tags.py" in render
  150.             return compiled_parent._render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\test\utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  937.                 bit = node.render_annotated(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render_annotated
  904.             return self.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\template_timings_panel\panels\TemplateTimings.py" in timing_hook
  139.         result = func(self, *args, **kwargs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\loader_tags.py" in render
  62.                 result = block.nodelist.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  937.                 bit = node.render_annotated(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render_annotated
  904.             return self.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\loader_tags.py" in render
  188.             return template.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\template_timings_panel\panels\TemplateTimings.py" in timing_hook
  139.         result = func(self, *args, **kwargs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  173.                 return self._render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\test\utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render
  937.                 bit = node.render_annotated(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\base.py" in render_annotated
  904.             return self.render(context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\template\defaulttags.py" in render
  166.             len_values = len(values)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in __len__
  250.         self._fetch_all()

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in _fetch_all
  1188.             self._prefetch_related_objects()

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in _prefetch_related_objects
  723.         prefetch_related_objects(self._result_cache, *self._prefetch_related_lookups)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in prefetch_related_objects
  1569.                 obj_list, additional_lookups = prefetch_one_level(obj_list, prefetcher, lookup, level)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in prefetch_one_level
  1699.     all_related_objects = list(rel_qs)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in __iter__
  268.         self._fetch_all()

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in _fetch_all
  1186.             self._result_cache = list(self._iterable_class(self))

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\query.py" in __iter__
  54.         results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\models\sql\compiler.py" in execute_sql
  1065.             cursor.execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\debug_toolbar\panels\sql\tracking.py" in execute
  186.         return self._record(self.cursor.execute, sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\debug_toolbar\panels\sql\tracking.py" in _record
  124.             return method(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in execute
  100.             return super().execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in execute
  68.         return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in _execute_with_wrappers
  77.         return executor(sql, params, many, context)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in _execute
  85.                 return self.cursor.execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\utils.py" in __exit__
  89.                 raise dj_exc_value.with_traceback(traceback) from exc_value

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\django\db\backends\utils.py" in _execute
  85.                 return self.cursor.execute(sql, params)

File "C:\Users\user\installed\anaconda\envs\django2\lib\site-packages\sql_server\pyodbc\base.py" in execute
  546.             return self.cursor.execute(sql, params)

Exception Type: Error at url
Exception Value: ('07002', '[07002] [Microsoft][SQL Server Native Client 11.0]COUNT field incorrect or syntax error (0) (SQLExecDirectW)')

Answer 1

它看起来不像是添加到django-pyodbc-azure：

https://github.com/michiya/django-pyodbc-azure/blob/azure-2.1/sql_server/pyodbc/features.py#L4

我把叉子放在这里：

https://github.com/FlipperPA/django-pyodbc-azure/blob/azure-2.1/sql_server/pyodbc/features.py#L33

你能试一试吗？您需要升级到Django 2.1，然后您应该能够pip install git+https://github.com/FlipperPA/django-pyodbc-azure.git@azure-2.1来查看它是否与添加该设置一样简单。粗略地看一下Django的源代码，看起来这可能就是它所需要的全部。如果行得通，我会向Michaya发出请求。在