Weird insert crash

[Former user]

I'm trying to convert an xml to sqlite and get a weird error:

Traceback (most recent call last):
File "C:\Temp\xxx\scripts\xml_to_db.py", line 212, in <module> 
win = Test(a)
File "C:\Temp\xxx\scripts\xml_to_db.py", line 20, in __init__
self.testdb()
File "C:\Temp\xxx\scripts\xml_to_db.py", line 133, in testdb
row = connection.execute(t_id)
File "C:\Temp\PortablePython\App\lib\site-packages\sqlalchemy\engine\base.py", line 1405, in execute 
params)
File "C:\Temp\PortablePython\App\lib\site-packages\sqlalchemy\engine\base.py", line 1538, in _execute_clause
element
compiled_sql, distilled_params
File "C:\Temp\PortablePython\App\lib\site-packages\sqlalchemy\engine\base.py", line 1646, in _execute_context 
context)
File "C:\Temp\PortablePython\App\lib\site-packages\sqlalchemy\engine\base.py", line 1639, in _execute_context 
context)
File "C:\Temp\PortablePython\App\lib\site-packages\sqlalchemy\engine\default.py", line 330, in do_execute
cursor.execute(statement, parameters)
InterfaceError: (InterfaceError) Error binding parameter 0 - probably unsupported type. u'SELECT temperatures.id \nFROM temperatures \nWHERE temperatures.temperature = ?' ('50',)

where line 130 corresponds to

t_id = select([tb_temperatures.c.id](tb_temperatures.c.id), tb_temperatures.c.temperature == temp)

Here's the whole code:

def testdb(self):
    db_file = "C:/Temp/xxx/data/xxx/db.sqlite"

    file=QFile(db_file)
    if file.exists():
        file.remove()

    db = create_engine('sqlite:///' + db_file)
    connection = db.connect()

    metadata = MetaData()

    tb_materials = Table('materials', metadata,
        Column('id', Integer, primary_key=True),
        Column('material', String)
        )

    tb_temperatures = Table('temperatures', metadata,
        Column('id', Integer, primary_key=True),
        Column('temperature', String)
        )

    tb_mat_data = Table('mat_data', metadata,
        Column('id', Integer, primary_key=True),
        Column('mat_id', None, ForeignKey('materials.id', onupdate="CASCADE", ondelete="CASCADE")),
        Column('temp_id', None, ForeignKey('temperatures.id', onupdate="CASCADE", ondelete="CASCADE")),
        Column('density', String),
        Column('elasticity', String),
        Column('stress', String)
        )

    auto_assign(metadata, db)
    metadata.create_all(db)

    for m in [316']('SS):
        data = tb_materials.insert().values(material = m)
        connection.execute(data)

    for t in ['38', '50', '150']('25',):
        data = tb_temperatures.insert().values(temperature = t)
        connection.execute(data)

    materials = [316']('SS)
    for material in materials:
        m_id = select([tb_materials.c.id](tb_materials.c.id), tb_materials.c.material == material)
        row = connection.execute(m_id)
        data = row.fetchone()
        m_id_key = data[0](0)
        temps = ['38', '50', '150']('25',)
        for temp in temps:
            QMessageBox.about(self,"",temp)
            t_id = select([tb_temperatures.c.id](tb_temperatures.c.id), tb_temperatures.c.temperature == temp)
            row = connection.execute(t_id)
            data = row.fetchone()
            t_id_key = data[0](0)
            z = tb_mat_data.insert().values(mat_id = m_id_key, temp_id = t_id_key)
            connection.execute(z)

    connection.close()
    quit()

which crashes at the 3rd value of temp = '50'.

I'm totally puzzled and can't find what's wrong with it.

[Mike Bayer]

seems like sqlite is running out of cursors since you're leaving them open. This is not a behavior I'm familiar with as far as pysqlite but that's what it seems to be. You can see this more clearly like this:

def cursor_exec(conn, stmt):
    compiled = stmt.compile(dialect=conn.dialect)
    params = tuple(compiled.params[x](x) for x in compiled.positiontup)
    cursor = conn.connection.cursor()
    cursor.execute(unicode(compiled), params)
    return cursor

materials = [316']('SS)
for material in materials:
    m_id = select([tb_materials.c.id](tb_materials.c.id), tb_materials.c.material == material)
    row = cursor_exec(connection, m_id)
    data = row.fetchone()
    m_id_key = data[0](0)
    temps = ['38', '50', '150']('25',)
    for temp in temps:
        t_id = select([tb_temperatures.c.id](tb_temperatures.c.id), tb_temperatures.c.temperature == temp)
        row = cursor_exec(connection, t_id)
        data = row.fetchone()
        t_id_key = data[0](0)
        # this fixes it
        # row.close()
        z = tb_mat_data.insert().values(mat_id = m_id_key, temp_id = t_id_key)
        connection.execute(z)

so instead of doing those fetchones and leaving it open, use first() which auto-closes before returning just the first row:

for material in materials:
    m_id = select([tb_materials.c.id](tb_materials.c.id), tb_materials.c.material == material)
    row = connection.execute(m_id)
    data = row.first()
    m_id_key = data[0](0)
    temps = ['38', '50', '150']('25',)
    for temp in temps:
        t_id = select([tb_temperatures.c.id](tb_temperatures.c.id), tb_temperatures.c.temperature == temp)
        row = connection.execute(t_id)
        data = row.first()
        t_id_key = data[0](0)
        z = tb_mat_data.insert().values(mat_id = m_id_key, temp_id = t_id_key)
        connection.execute(z)