How to insert multiple values ​​into a subquery using SQLAlchemy Core?

Question

Using SQLAlchemy Core (not ORM), I am trying to Insert multiple rows using subqueries in values. For MySQL, the actual SQL would look something like this:

INSERT INTO widgets (name, type) VALUES
('Melon', (SELECT type FROM widgetTypes WHERE type='Squidgy')),
('Durian', (SELECT type FROM widgetTypes WHERE type='Spiky'))

But it seems to me that I can use subqueries when using the values()on method insert(), which allows me to do only one insert at a time. I would like to insert several values ​​at once, passing them to the whole method Connection execute()as a list of binding parameters, but this does not seem to be supported.

Is it possible to do what I want in one call execute()?

There is a self-sufficient demonstration here. Note that this uses the sqlite mechanism, which does not support multiple attachments in the same way as MySQL , but the SQLAlchemy code still does not work the same as the actual MySQL application.

from sqlalchemy import *

if __name__ == "__main__":
    # Construct database
    metadata = MetaData()
    widgetTypes = Table('widgetTypes', metadata,
        Column('id', INTEGER(), primary_key=True),
        Column('type', VARCHAR(), nullable=False),
    )
    widgets = Table('widgets', metadata,
        Column('id', INTEGER(), primary_key=True),
        Column('name', VARCHAR(), nullable=False),
        Column('type', INTEGER(), nullable=False),
        ForeignKeyConstraint(['type'], ['widgetTypes.id']),
    )
    engine = create_engine("sqlite://")
    metadata.create_all(engine)

    # Connect and populate db for testing
    conn = engine.connect()
    conn.execute(widgetTypes.insert(), [
        {'type': 'Spiky'},
        {'type': 'Squidgy'},
    ])

    # Some select queries for later use.
    select_squidgy_id = select([widgetTypes.c.id]).where(
        widgetTypes.c['type']=='Squidgy'
    ).limit(1)
    select_spiky_id = select([widgetTypes.c.id]).where(
        widgetTypes.c['type']=='Squidgy'
    ).limit(1)

    # One at a time works via values()
    conn.execute(widgets.insert().values(
        {'name': 'Tomato', 'type': select_squidgy_id},
    ))

    # And multiple values work if we avoid subqueries
    conn.execute(
        widgets.insert(),
        {'name': 'Melon',  'type': 2},
        {'name': 'Durian', 'type': 1},
    )

    # Check above inserts did actually work
    print conn.execute(widgets.select()).fetchall()

    # But attempting to insert many at once with subqueries does not work.
    conn.execute(
        widgets.insert(),
        {'name': 'Raspberry', 'type': select_squidgy_id},
        {'name': 'Lychee',    'type': select_spiky_id},
    )

Run it and it will die on the last call execute()with:

sqlalchemy.exc.InterfaceError: (InterfaceError) Binding error parameter 1 - possibly an unsupported type. u'INSERT INTO widgets (name, type) VALUES (?,?) '(("Raspberry", <sqlalchemy.sql.expression.Select at 0x19f14d0; Select an object>), (' Lychee ', <sqlalchemy.sql.expression .Select at 0x19f1a50; Select an object>))

Answer 1

, subselect , INSERT:

type_select = select([widgetTypes.c.id]).where(
        widgetTypes.c.type==bindparam('type_name'))

insert = widgets.insert({'type': type_select})

conn.execute(insert, [
    {'name': 'Melon',  'type_name': 'Squidgy'},
    {'name': 'Lychee', 'type_name': 'Spiky'},
])