Question

我有一个sqlalchemy反映的表，该表指向teradata数据库中的表。问题在于，反射表显然没有在主键上启动。

td_engine = create_engine('teradata://'+user+':'+pswd+'@'+host)
Session = sessionmaker()
Session.configure(bind=td_engine)
pswd = getpass('Password:')
sess = Session()
metadata = MetaData(td_engine)
Base = declarative_base(cls=DeferredReflection)
class myTable(Base):
    __tablename__ = "table_name"
    __table_args__ = {'schema': 'schema_name'}
Base.prepare(td_engine)

当我运行Base.prepare(td_engine)时，会引发错误：

---------------------------------------------------------------------------
ArgumentError                             Traceback (most recent call last)
<ipython-input-9-f5961da6abab> in <module>()
      1 # declarative_base class Base imported from table_defs along with table class defs
----> 2 Base.prepare(td_engine)

~/anaconda3/envs/teradata37/lib/python3.6/site-packages/sqlalchemy/ext/declarative/api.py in prepare(cls, engine)
    691         for thingy in to_map:
    692             cls._sa_decl_prepare(thingy.local_table, engine)
--> 693             thingy.map()
    694             mapper = thingy.cls.__mapper__
    695             metadata = mapper.class_.metadata

~/anaconda3/envs/teradata37/lib/python3.6/site-packages/sqlalchemy/ext/declarative/base.py in map(self)
    641     def map(self):
    642         self._configs.pop(self._cls, None)
--> 643         return super(_DeferredMapperConfig, self).map()
    644 
    645 

~/anaconda3/envs/teradata37/lib/python3.6/site-packages/sqlalchemy/ext/declarative/base.py in map(self)
    574             self.cls,
    575             self.local_table,
--> 576             **self.mapper_args
    577         )
    578         del self.cls._sa_declared_attr_reg

<string> in mapper(class_, local_table, properties, primary_key, non_primary, inherits, inherit_condition, inherit_foreign_keys, extension, order_by, always_refresh, version_id_col, version_id_generator, polymorphic_on, _polymorphic_map, polymorphic_identity, concrete, with_polymorphic, polymorphic_load, allow_partial_pks, batch, column_prefix, include_properties, exclude_properties, passive_updates, passive_deletes, confirm_deleted_rows, eager_defaults, legacy_is_orphan, _compiled_cache_size)

~/anaconda3/envs/teradata37/lib/python3.6/site-packages/sqlalchemy/orm/mapper.py in __init__(self, class_, local_table, properties, primary_key, non_primary, inherits, inherit_condition, inherit_foreign_keys, extension, order_by, always_refresh, version_id_col, version_id_generator, polymorphic_on, _polymorphic_map, polymorphic_identity, concrete, with_polymorphic, polymorphic_load, allow_partial_pks, batch, column_prefix, include_properties, exclude_properties, passive_updates, passive_deletes, confirm_deleted_rows, eager_defaults, legacy_is_orphan, _compiled_cache_size)
    692             self._configure_properties()
    693             self._configure_polymorphic_setter()
--> 694             self._configure_pks()
    695             Mapper._new_mappers = True
    696             self._log("constructed")

~/anaconda3/envs/teradata37/lib/python3.6/site-packages/sqlalchemy/orm/mapper.py in _configure_pks(self)
   1325                 "Mapper %s could not assemble any primary "
   1326                 "key columns for mapped table '%s'" %
-> 1327                 (self, self.mapped_table.description))
   1328         elif self.local_table not in self._pks_by_table and \
   1329                 isinstance(self.local_table, schema.Table):

ArgumentError: Mapper Mapper|myTable|table_name could not assemble any primary key columns for mapped table 'table_name'

我忽略实现的反射表类有一些参数吗？任何帮助，我们将不胜感激。

sqlalchemy反映的表没有主键

0 个答案: