Hello,
I'm a beginner in SQLAlchemy - apologies if I'm asking for the
obvious...
I have a user defined type for Oracle (w/ SQLAlchemy 0.7.5)
class OracleBinaryDouble(sqlalchemy.types.UserDefinedType):
"""Native double / double precision floating point data type
for Oracle.
"""
def get_col_spec(self):
return "BINARY_DOUBLE"
which is then used in a type decorator to construct a matching user
defined type for all engines:
class BinaryDouble(sqlalchemy.types.TypeDecorator):
"""Platform-independent double precision floating point type.
Uses MySQL's DOUBLE and Oracle's BINARY_DOUBLE data type.
"""
impl = sqlalchemy.types.Numeric
def load_dialect_impl(self, dialect):
if dialect.name == 'mysql':
return
dialect.type_descriptor(sqlalchemy.dialects.mysql.FLOAT(53))
elif dialect.name == 'sqlite':
return
dialect.type_descriptor(sqlalchemy.dialects.sqlite.FLOAT)
elif dialect.name == 'oracle':
return dialect.type_descriptor(OracleBinaryDouble)
elif dialect.name == 'postgresql':
return
dialect.type_descriptor(sqlalchemy.dialects.postgresql.DOUBLE_PRECISION)
else:
return dialect.type_descriptor(FLOAT(53)) # 53+ bit
mantissa is a double precision number
When defining a database table, i.e. like
meta = MetaData()
level1a = Table('level1a', meta,
Column('l1a_file', String(333),
primary_key = True),
Column('lon', BinaryDouble),
Column('lat', BinaryDouble)
)
working with that table is fine, and works as intended (i.e., storing
double precision floating point numbers as BINARY_DOUBLE in Oracle.
When reflecting this table in Oracle, as in
Base = sqlalchemy.ext.declarative.declarative_base()
class Level1a(Base):
__table__ = sqlalchemy.Table("level1a", Base.metadata,
autoload = True, autoload_with =
engine)
I receive warnings from the Oracle driver, saying
.../python2.7/site-packages/sqlalchemy/engine/reflection.py:47:
SAWarning: Did not recognize type 'BINARY_DOUBLE' of column 'lon'
ret = fn(self, con, *args, **kw)
.../python2.7/site-packages/sqlalchemy/engine/reflection.py:47:
SAWarning: Did not recognize type 'BINARY_DOUBLE' of column 'lat'
ret = fn(self, con, *args, **kw)
What am I missing (or doing wrong)? I assume that the BinaryDouble
type must be registered somehow, but how?
Many thanks,
Christian.
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