python sqlalchemy insert multiple lines in a tuple data structure

Question

I have been researching how to insert a list of ~500 tuples (rows) that has 7 elements (columns) into a database. I have read through various posts on stackoverflow as well as other forums. I found the following and it suggests to use the 'executemany()' method but its not so clear to me how. Do I need to covert my object from tuple to a dictionary? The problem is I don't have a name:value type of data structure.

How to use SQLAlchemy to dump an SQL file from query expressions to bulk-insert into a DBMS?

Here is an example:

engine = create_engine('sqlite:///:memory:', echo=True)
metadata = MetaData()
hockey= Table('hockey', metadata, 
    Column('team', String(16), primary_key=True),
    Column('jersey_colour', String(16)),
    Column('stadium', String(32)),
    Column('goals', Integer),
    Column('date', Date, primary_key=True),
    Column('assists', Integer))

>>>data[0]
[(u'Maple Leafs', u'Blue', u'Air Canada Center', 151, '2013-03-25', 301)]

Edit:

I tried the solution described (Sqlalchemy core, insert multiple rows from a tuple instead of dict) as follows:

markers = ','.join('?' * len(data[0]))
ins = 'INSERT INTO {tablename} VALUES ({markers})'
ins = ins.format(tablename=hockey.name, markers=markers)

>>str(ins)
'INSERT INTO hockey VALUES (?,?,?,?,?,?)'

conn = engine.connect()
result = conn.execute(ins, data)

In [59]: result = conn.execute(ins, data)
2013-03-26 07:29:28,371 INFO sqlalchemy.engine.base.Engine INSERT INTO hockey VALUES (?,?,?,?,?,?)
2013-03-26 07:29:28,371 INFO sqlalchemy.engine.base.Engine (u'Maple Leafs', u'Blue', u'Air Canada Center', 151, '2013-03-25', 301)
2013-03-26 07:29:28,371 INFO sqlalchemy.engine.base.Engine ROLLBACK
---------------------------------------------------------------------------
OperationalError                          Traceback (most recent call last)
<ipython-input-59-dafe2aef2c66> in <module>()
----> 1 result = conn.execute(ins, data)

/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in execute(self, object, *multiparams, **params)
    662                                                 object,
    663                                                 multiparams,
--> 664                                                 params)
    665         else:
    666             raise exc.InvalidRequestError(

/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _execute_text(self, statement, multiparams, params)
    806             statement,
    807             parameters,
--> 808             statement, parameters
    809         )
    810         if self._has_events:

/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _execute_context(self, dialect, constructor, statement, parameters, *args)
    876                                 parameters,
    877                                 cursor,
--> 878                                 context)
    879             raise
    880

/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.pyc in _execute_context(self, dialect, constructor, statement, parameters, *args)
    869                                     statement,
    870                                     parameters,
--> 871                                     context)
    872         except Exception, e:
    873             self._handle_dbapi_exception(

/usr/lib/python2.7/site-packages/sqlalchemy/engine/default.pyc in do_execute(self, cursor, statement, parameters, context)
    318
    319     def do_execute(self, cursor, statement, parameters, context=None):
--> 320         cursor.execute(statement, parameters)
    321
    322     def do_execute_no_params(self, cursor, statement, context=None):

OperationalError: (OperationalError) near "hockey": syntax error 'INSERT INTO hockey VALUES (?,?,?,?,?,?)' (u'Maple Leafs', u'Blue', u'Air Canada Center', 151, '2013-03-25', 301)

There error:

  OperationalError: (OperationalError) near "hockey": syntax error 'INSERT INTO hockey VALUES (?,?,?,?,?,?)' (u'Maple Leafs', u'Blue', u'Air Canada Center', 151, '2013-03-25', 301)

Tipton

It looks like you DO have to supply a list of dictionaries according to the tutorial To issue many inserts using DBAPI’s executemany() method, we can send in a list of dictionaries each containing a distinct set of parameters to be inserted, as we do here to add some email addresses:. Just convert the tuple into dictionary. – Icecap

Thanks CppLearner. So when I convert the tuple to a dict does it matter what the key field is? Does the key field have to match the column names in the table? Appreciate your help. Thank you. – Tipton

yes! The name of the dictionary key should match the attribute (or field) name in the database! so use whatever you have for Column. T – Icecap

Answer 1

Well I did the following:

column_names = tuple(c.name for c in hockey.c)

>>>column_names
('team', 'jersey_colour', 'stadium', 'goals', 'date', 'assists')

final = [dict(zip(column_names,x)) for x in data]

The above creates a list of dictionaries for each or the rows. This should work but when I run I get the following error:

>>>conn.execute(ins, final)

SQLite Date type only accepts Python date objects as input.

In any case this is another problem that I need to look into. That said, I am answering and accepting this question because the above dictionary should work.

Tipton

Answer 2

Hello from the future!

I found myself also wanting to do bulk data insertions based on an existing SQLAlchemy table (or model, inheriting from declarative_base() in my case). I also chafed at the idea of having to create a dictionary on-the-fly just to do insertions, and went looking for a more straightforward way.

I'm sure a lot has changed since you asked/answered this question in 2013, but in 2021, with SQLAlchemy 1.4 and Python 3.7.something, here is what worked for me:

from sqlalchemy import create_engine, MetaData, Table, Column, String, Integer

engine = create_engine('sqlite:///:memory:', echo=True)
metadata = MetaData(bind=engine)

hockey = Table('hockey', metadata, 
    Column('team', String(16), primary_key=True),
    Column('jersey_colour', String(16)),
    Column('stadium', String(32)),
    Column('goals', Integer),
    Column('date', String(10), primary_key=True),
    Column('assists', Integer))

data = [
    ['Blue', 'Toronto Maple Leafs', 'Air Canada Center', '2013-03-25', 301, 151], 
    ['Red', 'Calgary Flames', 'PenWest', '2013-03-25', 254, 147]
]

metadata.create_all()
engine.execute(hockey.insert().values(data))

You might notice that I changed the date field to a string, for simplicity, since the SQLite DB-API library wants a Python datetime.date for those as noted here. (Anyone puzzled by this little sleight-of–hand should see this answer for clarification.)

Anyway, inserting a two-dimensional data structure into a SQLite database using .insert().values works fine nowadays, without the dict(zip(…)) rigamarole.

>>> from sqlalchemy import select
>>> engine.execute(select(hockey)).all()

[('Blue', 'Toronto Maple Leafs', 'Air Canada Center', '2013-03-25', '301', 151),
 ('Red', 'Calgary Flames', 'PenWest', '2013-03-25', '254', 147)]

Tavis

How it can be acheived using raw sql instead of orm? – Barrier