Python clickhouse-driver: ValueError: Parameters are expected in dict form

Python clickhouse-driver: ValueError: Parameters are expected in dict form

我有一些 ETL 可以使用 clickhouse-driver 将数据保存到 clickhouse。

保存函数看起来完全像这样:

def insert_data(data: Iterable[Dict], table: str, client: Client = None):
    columns = get_table_cols(table)
    client = client or get_ch_client(0)
    query = f"insert into {table} ({', '.join(columns)}) values"
    data = map(lambda row: {key: row[key] for key in columns}, data)
    client.execute(query, data)

调用 insert_data 的函数如下所示:

def save_data(data: DataFrame, client: Client):

    mapper = get_mapper(my_table_map)
    data = map(lambda x: {col_new: getattr(x, col_old)
                          for col_old, col_new in map_dataframe_to_ch.items()},
               data.collect())
    data = map(mapper, data)
    insert_data(data, 'my_table_name', client)

get_mapper returns 一个看起来像这样的地图函数:

def map_row(row: Dict[str, Any]) -> Dict[str, Any]:
    nonlocal map_
    return {key: map_[key](val) for key, val in row.items()}

所以基本上最后我有一些生成字典的嵌套生成器。为了确认这一点,如果我把 print(next(data)) 放在 client.execute 之前,我就会得到我期望的命令。这是一个隐藏敏感信息的示例:

{'account_currency': '***', 
 'instrument': '***',
 'operation': 'open',
 'event_time': datetime.datetime(2020, 7, 7, 19, 11, 49),
 'country': 'CN',
 'region': 'Asia and Pacific',
 'registration_source': '***',
 'account_type': '***',
 'platform': '***',
 'server_key': '***'}

Table架构如下:

"account_currency": "String",
"instrument": "String",
"operation": "String",
"event_time": "DateTime",
"country": "String",
"region": "String",
"registration_source": "String",
"account_type": "String",
"platform": "String",
"server_key": "String"

但无论出于何种原因,我收到此错误:

  File "src/etl/usd_volume/prepare_users.py", line 356, in <module>
    main()
  File "src/etl/usd_volume/prepare_users.py", line 348, in main
    save_data(data, client)
  File "src/etl/usd_volume/prepare_users.py", line 302, in save_data
    insert_data(data, 'report_traded_volume_usd', client)
  File "/root/data/src/common/clickhouse_helper.py", line 14, in insert_data
    client.execute(query, data)
  File "/usr/local/lib/python3.6/dist-packages/clickhouse_driver/client.py", line 224, in execute
    columnar=columnar
  File "/usr/local/lib/python3.6/dist-packages/clickhouse_driver/client.py", line 341, in process_ordinary_query
    query = self.substitute_params(query, params)
  File "/usr/local/lib/python3.6/dist-packages/clickhouse_driver/client.py", line 422, in substitute_params
    raise ValueError('Parameters are expected in dict form')

根据文档:

:param params: substitution parameters for SELECT queries and data for INSERT queries. Data for INSERT can be list, tuple or :data:~types.GeneratorType. Defaults to None (no parameters or data).

很明显我的数据符合这些要求。

然而在源代码中只有这个检查:

def substitute_params(self, query, params):
    if not isinstance(params, dict):
        raise ValueError('Parameters are expected in dict form')

    escaped = escape_params(params)
    return query % escaped

我没有真正找到他们在哪里检查它是否是发电机。 Clickhouse-driver 版本为 0.1.4

非常感谢对此问题的任何帮助。

好的,进一步研究源代码揭示了根本原因。

Client class 的 process_ordinary_query 方法中调用了抛出错误 substitute_params 的函数。除了 INSERT.

之外的任何查询基本上都会调用此方法

execute 方法的这一部分检查查询的符号是 INSERT 还是任何其他:

is_insert = isinstance(params, (list, tuple, types.GeneratorType))

if is_insert:
    rv = self.process_insert_query(
        query, params, external_tables=external_tables,
        query_id=query_id, types_check=types_check,
        columnar=columnar
    )
else:
    rv = self.process_ordinary_query(
        query, params=params, with_column_types=with_column_types,
        external_tables=external_tables,
        query_id=query_id, types_check=types_check,
        columnar=columnar
    )

关键是isinstance(params, (list, tuple, types.GeneratorType))

types.GeneratorType定义如下:

def _g():
    yield 1
GeneratorType = type(_g())

由此导致:

>>>GeneratorType
<class 'generator'>

显然,对于我的数据是 map:

>>>type(map(...))
<class 'map'>
>>>isinstance(map(...), GeneratorType)
False

因此,避免此问题的最简单解决方案是简单地将 data 转换为生成器理解的生成器。这完全解决了问题。

>>>data = (i for i in data)
>>>isinstance(data, GeneratorType)
True

或者,如果您要专门执行 INSERT 查询,您可以直接调用 process_insert_query,这样就无需将数据转换为生成器。

我认为 clickhouse-driver 的类型检查有点模糊,但这就是我们所拥有的。