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|
"""Support for the PostgreSQL database via the pg8000 driver.
Connecting
----------
URLs are of the form
`postgresql+pg8000://user:password@host:port/dbname[?key=value&key=value...]`.
Unicode
-------
pg8000 requires that the postgresql client encoding be configured in the postgresql.conf file
in order to use encodings other than ascii. Set this value to the same value as
the "encoding" parameter on create_engine(), usually "utf-8".
Interval
--------
Passing data from/to the Interval type is not supported as of yet.
"""
import decimal
from sqlalchemy.engine import default
from sqlalchemy import util, exc
from sqlalchemy import processors
from sqlalchemy import types as sqltypes
from sqlalchemy.dialects.postgresql.base import PGDialect, \
PGCompiler, PGIdentifierPreparer, PGExecutionContext
class _PGNumeric(sqltypes.Numeric):
def bind_processor(self, dialect):
return processors.to_float
def result_processor(self, dialect, coltype):
if self.asdecimal:
if coltype in (700, 701):
return processors.to_decimal_processor_factory(decimal.Decimal)
elif coltype == 1700:
# pg8000 returns Decimal natively for 1700
return None
else:
raise exc.InvalidRequestError("Unknown PG numeric type: %d" % coltype)
else:
if coltype in (700, 701):
# pg8000 returns float natively for 701
return None
elif coltype == 1700:
return processors.to_float
else:
raise exc.InvalidRequestError("Unknown PG numeric type: %d" % coltype)
class PostgreSQL_pg8000ExecutionContext(PGExecutionContext):
pass
class PostgreSQL_pg8000Compiler(PGCompiler):
def visit_mod(self, binary, **kw):
return self.process(binary.left) + " %% " + self.process(binary.right)
def post_process_text(self, text):
if '%%' in text:
util.warn("The SQLAlchemy postgresql dialect now automatically escapes '%' in text() "
"expressions to '%%'.")
return text.replace('%', '%%')
class PostgreSQL_pg8000IdentifierPreparer(PGIdentifierPreparer):
def _escape_identifier(self, value):
value = value.replace(self.escape_quote, self.escape_to_quote)
return value.replace('%', '%%')
class PostgreSQL_pg8000(PGDialect):
driver = 'pg8000'
supports_unicode_statements = True
supports_unicode_binds = True
default_paramstyle = 'format'
supports_sane_multi_rowcount = False
execution_ctx_cls = PostgreSQL_pg8000ExecutionContext
statement_compiler = PostgreSQL_pg8000Compiler
preparer = PostgreSQL_pg8000IdentifierPreparer
colspecs = util.update_copy(
PGDialect.colspecs,
{
sqltypes.Numeric : _PGNumeric,
}
)
@classmethod
def dbapi(cls):
return __import__('pg8000').dbapi
def create_connect_args(self, url):
opts = url.translate_connect_args(username='user')
if 'port' in opts:
opts['port'] = int(opts['port'])
opts.update(url.query)
return ([], opts)
def is_disconnect(self, e):
return "connection is closed" in str(e)
dialect = PostgreSQL_pg8000
|
