Agfdhyk

I am trying to use the if_exists pandas to_sql arguments with sqlalchemy and i cannot seem to get it to work

versions

• sqlalchemy version 1.2.12


• pandas version 0.23.4


• 
  

  python 3.5.2

  
  
  

  engine = create_engine(postgress_connection_string, echo=True)
  
  df1 = pd.DataFrame([['Abe','1','True'],['Ben','2','True'],['Charlie','3','True']], columns=['Name','Number','Other'])
  
  
  
  df1.to_sql('df_tbl',engine) #works if table doesn't exist, else fails
  
  df1.to_sql('df_tbl',engine, if_exists='replace') #fails with error message
  
  

  
  

error: AttributeError: 'Connection' object has no attribute '_engine'

debug output

--------------------------------------------------------------------------- AttributeError Traceback (most recent call
last) in
7 df_rides_stops.rename(index=str, columns={'orig_ad_id':'ad_id',
'orig_stay_time':'stay_time','orig_arrival_utc':'arrival_utc'},inplace=True)
8 df_rides_stops.head()
----> 9 df_rides_stops.to_sql('rides',engine, if_exists='replace')
10

~/dev/Ride/qgis3/lib/python3.5/site-packages/pandas/core/generic.py in
to_sql(self, name, con, schema, if_exists, index, index_label,
chunksize, dtype) 2128 sql.to_sql(self, name, con,
schema=schema, if_exists=if_exists, 2129

index=index, index_label=index_label, chunksize=chunksize,
-> 2130 dtype=dtype) 2131 2132 def to_pickle(self, path, compression='infer',

~/dev/Ride/qgis3/lib/python3.5/site-packages/pandas/io/sql.py in
to_sql(frame, name, con, schema, if_exists, index, index_label,
chunksize, dtype)
448 pandas_sql.to_sql(frame, name, if_exists=if_exists, index=index,
449 index_label=index_label, schema=schema,
--> 450 chunksize=chunksize, dtype=dtype)
451
452

~/dev/Ride/qgis3/lib/python3.5/site-packages/pandas/io/sql.py in
to_sql(self, frame, name, if_exists, index, index_label, schema,
chunksize, dtype) 1124

if_exists=if_exists, index_label=index_label, 1125

schema=schema, dtype=dtype)
-> 1126 table.create() 1127 table.insert(chunksize) 1128 if (not name.isdigit() and not name.islower()):

~/dev/Ride/qgis3/lib/python3.5/site-packages/pandas/io/sql.py in
create(self)
563 raise ValueError("Table '%s' already exists." % self.name)
564 elif self.if_exists == 'replace':
--> 565 self.pd_sql.drop_table(self.name, self.schema)
566 self._execute_create()
567 elif self.if_exists == 'append':

~/dev/Ride/qgis3/lib/python3.5/site-packages/pandas/io/sql.py in
drop_table(self, table_name, schema) 1173 schema = schema
or self.meta.schema 1174 if self.has_table(table_name,
schema):
-> 1175 self.meta.reflect(only=[table_name], schema=schema) 1176 self.get_table(table_name,
schema).drop() 1177 self.meta.clear()

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/sql/schema.py
in reflect(self, bind, schema, views, only, extend_existing,
autoload_replace, **dialect_kwargs) 3961 for name in
load: 3962 try:
-> 3963 Table(name, self, **reflect_opts) 3964 except exc.UnreflectableTableError as uerr: 3965

util.warn("Skipping table %s: %s" % (name, uerr))

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/sql/schema.py
in new(cls, *args, **kw)
455 except:
456 with util.safe_reraise():
--> 457 metadata._remove_table(name, schema)
458
459 @property

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/util/langhelpers.py
in exit(self, type_, value, traceback)
64 self._exc_info = None # remove potential circular references
65 if not self.warn_only:
---> 66 compat.reraise(exc_type, exc_value, exc_tb)
67 else:
68 if not compat.py3k and self._exc_info and self._exc_info[1]:

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/util/compat.py
in reraise(tp, value, tb, cause)
247 if value.traceback is not tb:
248 raise value.with_traceback(tb)
--> 249 raise value
250
251 else:

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/sql/schema.py
in new(cls, *args, **kw)
450 metadata._add_table(name, schema, table)
451 try:
--> 452 table._init(name, metadata, *args, **kw)
453 table.dispatch.after_parent_attach(table, metadata)
454 return table

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/sql/schema.py
in _init(self, name, metadata, *args, **kwargs)
532 self._autoload(
533 metadata, autoload_with,
--> 534 include_columns, _extend_on=_extend_on)
535
536 # initialize all the column, etc. objects. done after reflection to

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/sql/schema.py
in _autoload(self, metadata, autoload_with, include_columns,
exclude_columns, _extend_on)
545 autoload_with.dialect.reflecttable,
546 self, include_columns, exclude_columns,
--> 547 _extend_on=_extend_on
548 )
549 else:

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/engine/base.py
in run_callable(self, callable_, *args, **kwargs) 1543 1544

"""
-> 1545 return callable_(self, *args, **kwargs) 1546 1547 def _run_visitor(self, visitorcallable, element, **kwargs):

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/engine/default.py
in reflecttable(self, connection, table, include_columns,
exclude_columns, **opts)
387 def reflecttable(
388 self, connection, table, include_columns, exclude_columns, **opts):
--> 389 insp = reflection.Inspector.from_engine(connection)
390 return insp.reflecttable(
391 table, include_columns, exclude_columns, **opts)

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/engine/reflection.py
in from_engine(cls, bind)
132 """
133 if hasattr(bind.dialect, 'inspector'):
--> 134 return bind.dialect.inspector(bind)
135 return Inspector(bind)
136

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/dialects/postgresql/base.py
in init(self, conn) 2026 2027 def init(self, conn):
-> 2028 reflection.Inspector.init(self, conn) 2029 2030 def get_table_oid(self, table_name, schema=None):

~/dev/Ride/qgis3/lib/python3.5/site-packages/sqlalchemy/engine/reflection.py
in init(self, bind)
101 # set the engine
102 if hasattr(bind, 'engine'):
--> 103 self.engine = bind._engine
104 else:
105 self.engine = bind

AttributeError: 'Connection' object has no attribute '_engine'