SQLAlchemy：查询在传递整数参数时出错

Question

我正在使用 SQLAchemy 和 python 来动态运行 SQL 查询。但它给出了错误。

这是我运行查询的命令：

data = engine.execute(m_query, week=Cohort_week, metric=metric, p1=val1, p2=val2).fetchall()

这里是 Cohort_week，val1,val2 是整数，metric 是字符串。

这是我的 SQL 查询：

    select cus.week,pdp_views, id, :metric,
    case
       when :metric <= :p2 then 3
       when :metric > :p2 and :metric < :p1 then 2 
       when :metric >= :p1 then 1
    end as HML
    from 
    dev.master_abtest_customers  cus
    where cus.week=  :week

错误是：

DataError                                 Traceback (most recent call last)
<ipython-input-25-30f7e92cbea3> in <module>()
     12 m_query = text(m_query)
     13 
---> 14 data = engine.execute(m_query, week=week, metric=metric, p1=val1, p2=val2).fetchall()
     15 
     16 data = pd.DataFrame(data)

C:\Users\MI0185\AppData\Local\Enthought\Canopy\User\lib\site-packages\sqlalchemy-1.1.0b1-py2.7-win-amd64.egg\sqlalchemy\engine\base.pyc in execute(self, statement, *multiparams, **params)
   2050 
   2051         connection = self.contextual_connect(close_with_result=True)
-> 2052         return connection.execute(statement, *multiparams, **params)
   2053 
   2054     def scalar(self, statement, *multiparams, **params):

C:\Users\MI0185\AppData\Local\Enthought\Canopy\User\lib\site-packages\sqlalchemy-1.1.0b1-py2.7-win-amd64.egg\sqlalchemy\engine\base.pyc in execute(self, object, *multiparams, **params)
    945                 type(object))
    946         else:
--> 947             return meth(self, multiparams, params)
    948 
    949     def _execute_function(self, func, multiparams, params):

C:\Users\MI0185\AppData\Local\Enthought\Canopy\User\lib\site-packages\sqlalchemy-1.1.0b1-py2.7-win-amd64.egg\sqlalchemy\sql\elements.pyc in _execute_on_connection(self, connection, multiparams, params)
    260 
    261     def _execute_on_connection(self, connection, multiparams, params):
--> 262         return connection._execute_clauseelement(self, multiparams, params)
    263 
    264     def unique_params(self, *optionaldict, **kwargs):

C:\Users\MI0185\AppData\Local\Enthought\Canopy\User\lib\site-packages\sqlalchemy-1.1.0b1-py2.7-win-amd64.egg\sqlalchemy\engine\base.pyc in _execute_clauseelement(self, elem, multiparams, params)
   1053             compiled_sql,
   1054             distilled_params,
-> 1055             compiled_sql, distilled_params
   1056         )
   1057         if self._has_events or self.engine._has_events:

C:\Users\MI0185\AppData\Local\Enthought\Canopy\User\lib\site-packages\sqlalchemy-1.1.0b1-py2.7-win-amd64.egg\sqlalchemy\engine\base.pyc in _execute_context(self, dialect, constructor, statement, parameters, *args)
   1189                 parameters,
   1190                 cursor,
-> 1191                 context)
   1192 
   1193         if self._has_events or self.engine._has_events:

C:\Users\MI0185\AppData\Local\Enthought\Canopy\User\lib\site-packages\sqlalchemy-1.1.0b1-py2.7-win-amd64.egg\sqlalchemy\engine\base.pyc in _handle_dbapi_exception(self, e, statement, parameters, cursor, context)
   1384                 util.raise_from_cause(
   1385                     sqlalchemy_exception,
-> 1386                     exc_info
   1387                 )
   1388             else:

C:\Users\MI0185\AppData\Local\Enthought\Canopy\User\lib\site-packages\sqlalchemy-1.1.0b1-py2.7-win-amd64.egg\sqlalchemy\util\compat.pyc in raise_from_cause(exception, exc_info)
    200     exc_type, exc_value, exc_tb = exc_info
    201     cause = exc_value if exc_value is not exception else None
--> 202     reraise(type(exception), exception, tb=exc_tb, cause=cause)
    203 
    204 if py3k:

C:\Users\MI0185\AppData\Local\Enthought\Canopy\User\lib\site-packages\sqlalchemy-1.1.0b1-py2.7-win-amd64.egg\sqlalchemy\engine\base.pyc in _execute_context(self, dialect, constructor, statement, parameters, *args)
   1182                         statement,
   1183                         parameters,
-> 1184                         context)
   1185         except Exception as e:
   1186             self._handle_dbapi_exception(

C:\Users\MI0185\AppData\Local\Enthought\Canopy\User\lib\site-packages\sqlalchemy-1.1.0b1-py2.7-win-amd64.egg\sqlalchemy\engine\default.pyc in do_execute(self, cursor, statement, parameters, context)
    460 
    461     def do_execute(self, cursor, statement, parameters, context=None):
--> 462         cursor.execute(statement, parameters)
    463 
    464     def do_execute_no_params(self, cursor, statement, context=None):

DataError: (psycopg2.DataError) invalid input syntax for integer: "pdp_views"
 [SQL: 'select cus.week, id, %(metric)s,\n        case\n           when %(metric)s <= %(p2)s then 3\n           when %(metric)s > %(p2)s and %(metric)s < %(p1)s then 2 \n           when %(metric)s >= %(p1)s then 1\n        end as HML\n        from \n        dev.master_abtest_customers  cus\n        where cus.week=  %(week)s\n\t\t\n\t\t'] [parameters: {'p2': 20L, 'week': 22L, 'metric': u'pdp_views', 'p1': 40L}]

我尝试过将 val1、val2 和 week 类型转换为 int（即使用 int(val1) 等）。但仍然是同样的错误。

你能帮我解决这个问题吗

Answer 1

看起来您想将pdp_views 列中的值与p1 和p2 进行比较，但实际上您正在将字符串'pdp_views' 与p1 和p2 进行比较，这有不兼容的类型。

您应该改为动态构建查询：

def get_m_query(week, metric, p1, p2):
    cus = master_abtest_customers.alias("cus")
    metric = getattr(cus.c, metric)
    return select([
        cus.c.week,
        cus.c.pdp_views,
        cus.c.id,
        metric,
        case([
            (metric <= p2, 3),
            (and_(metric > p2, metric < p1), 2),
            (metric >= p1, 1),
        ]).label("HML"),
    ]).select_from(cus).where(cus.week == week)